And despite what it tells its victims, it seems designed to destroy data irrevocably rather than encrypt it reversibly.
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While encryption is in a way just transforming one block of data reversibly into another, that process is actually pretty complicated.
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Case in point: A pair of trousers in the season's must-have check can be turned inside out and worn reversibly.
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Similarly Johnny Storms ability to (reversibly) turn into superheated plasma must stay firmly in the realm of fantasy, it needs just too much energy.
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These joints allow the creatures' wings to stay stiff during flight, but "reversibly crumple" in the case of a crash — saving the thin membranes from tearing.
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VIENNA (Reuters) - The U.N. atomic watchdog on Monday acknowledged Iran's latest announcement on walking away, though reversibly, from its nuclear containment deal with major powers and said it would report any developments promptly to its member states.
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How it works: Inspired by octopuses and other cephalopods — which can reversibly change the texture of their skin at high speed — scientists built a silicone structure embedded with a fiber mesh that allows it to contort, lead researcher James Pikul tells Axios.
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Methamphetamines decrease Vmax, while cocaine increases Vmax reversibly in rat brain.
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The first synthetic oxygen complex was demonstrated in 1938 with cobalt(II) complex reversibly bound O2.
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Ascorbic acid also converts (reversibly) to dehydroascorbate (DHA) and from that compound non-reversibly to 2,3-diketogluonate and then oxalate. These three compounds are also excreted via urine. Humans are better than guinea pigs at converting DHA back to ascorbate, and thus take much longer to become vitamin C deficient.
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Transcript variants encoding different isoforms have been noted for this gene. The CYP11B1 gene is reversibly inhibited by etomidate and metyrapone.
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4,4'-Diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) is an anion exchange inhibitor, blocking reversibly, and later irreversibly, exchangers such as chloride-bicarbonate exchanger.
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It is a multifunctional epidermal matrix protein. RPTN reversibly binds calcium. RPTN is 5,634 bases long. It starts 152,126,071 base pairs from pter.
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Cholecalciferol is very sensitive to UV radiation and will rapidly, but reversibly, break down to form supra-sterols, which can further irreversibly convert to ergosterol.
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Reversibly photoswitchable proteins can switch back and forth between two optically separated states, making them useful for high-contrast and high resolution PA imaging. Yao et al. demonstrated differential imaging of the reversibly switchable phytochrome BphP1 in in vivo experiments (terming the technology RS-PAM). The two states of the BphP1 molecule are the Pfr and Pf states, referred to as the ON and OFF states, respectively.
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Quinacillin is a penicillin antibiotic which can reversibly deactivate beta- lactamase enzymes. Activity against Staphylococcus aureus is much more potent than against other Gram-positive organisms.
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The top molecule is bound reversibly, but the lower one is bound covalently as it has reacted with an amino acid residue through its nitrogen mustard group.
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Under conditions of starvation or desiccation, the amoebae differentiate reversibly into dormant spores with cell walls. When immersed in water, amoebae differentiate reversibly into flagellated cells, which involves a major reorganization of the cytoskeleton. The plasmodium is typically diploid and propagates via growth and nuclear division without cytokinesis, resulting in the macroscopic multinucleate syncytium. While nutrients are available, the network-shaped plasmodium can grow to a foot or more in diameter.
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However, increase polymer length inhibits mobility and thereby impairs the ability for polymers to re-reversibly bond. Thus at each polymer length an optimal reversible bonding energy exists.
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The entropy transfer here is analogous to the entropy transfer in algorithmic cooling, in the sense that by applying external work entropy can be transferred reversibly between qubits.
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The observed C-C distance of 120 pm indicates the presence of a C≡C triple bond. At high temperatures transforms reversibly to a cubic anti-fluorite structure.
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Acetone cyanohydrin can be used to reversibly generate the cyanide anion.Nazarov, N. ; Zav'yalov, I. J. Gen. Chem. USSR (Engl. Transl.) 1954, 24, 475 [C.A., 49, 6139f (1955)]. (4)File:CNAddScope1.
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This application exploits the ability of zirconium to reversibly form bonds to carbon. Most complexes of Zr(II) are derivatives of zirconocene, one example being (C5Me5)2Zr(CO)2.
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Antiplatelet drugs can reversibly or irreversibly inhibit the process involved in platelet activation resulting in decreased tendency of platelets to adhere to one another and to damaged blood vessels' endothelium.
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Human and some bacterial GALE isoforms reversibly catalyze the conversion of UDP-GlcNAc to UDP-GalNAc through an identical mechanism, inverting the stereochemical configuration at the sugar's 4' hydroxyl group.
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Hemitoxin (HTX; α-KTx6.15) is a 35-mer basic peptide from the venom of the Iranian scorpion Hemiscorpius lepturus, which reversibly blocks Kv1.1, Kv1.2 and Kv1.3 voltage-gated K+ channels.
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Delta- toxin is an elastase activated by Ca2+ ions. This proteolytic enzyme is inhibited by cysteine and reversibly inactivated by reducing agents. The molecular weight is between 10 and 50 kDa.
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Ticagrelor (Brilinta) is often listed with thienopyridine inhibitors and has similar indications for use but is not a thienopyridine. It is a cyclo-pentyltriazolo-pyrimidine that reversibly inhibits the P2Y12 receptor.
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The main storage methods for passwords are plain text, hashed, hashed and salted, and reversibly encrypted.Florencio et al., An Administrator's Guide to Internet Password Research . (pdf) Retrieved on 2015-03-14.
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Reversibly assembled cellular composite materials (RCCM) are three-dimensional lattices of modular structures that can be partially disassembled to enable repairs or other modifications. Each cell incorporates structural material and a reversible interlock, allowing lattices of arbitrary size and shape. RCCM display three-dimensional symmetry derived from the geometry as linked. The discrete construction of reversibly assembled cellular composites introduces a new degree of freedom that determines global functional properties from the local placement of heterogeneous components.
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Tetrindole was a drug candidate that functions by reversibly inhibiting monoamine oxidase A; it was first synthesized in Moscow in the early 1990s. Tetrindole is similar in its chemical structure to pirlindole (Pyrazidol), and metralindole.
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In constast to analogous structures with earlier chalcogens, selones greater steric and electronic stabilization. Selenobenzophenone reversibly dimerizes. It is known to undergo cycloaddition with 1,3-dienes in a reaction similar to the Diels- Alder reaction.
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Dynamic covalent reactions have recently been used in Systems chemistry to initiate signaling cascades by reversibly releasing protons. The dynamic nature of the reactions provides a suitable "on-off" switch-like nature to the cascade systems.
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A tetrameric, reversibly switchable fluorescent protein was discovered in a cDNA screen of a stony coral (Pectiniidae). A monomeric variant of this protein was named "Dronpa" after "Dron" a ninja term for vanishing and pa for photoactivation.
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The actual mechanism for the onset of anesthesia is unknown, but it is believed that the active ingredients reversibly block nerve conduction therefore causing the numbing sensation. This stabilizes the neuron and prevents signals from being transferred.
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After the first dose the half life is 12.6 hours, but with repeated dosing the maximum half life is 4–5 days. Clearance is also slower in the elderly. The drug is 98% reversibly bound to proteins.
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In oxidizing conditions it can reversibly react with strong acids to form the ferrocenium cation . The rapid growth of organometallic chemistry is often attributed to the excitement arising from the discovery of ferrocene and its many analogues (metallocenes).
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Such species reversibly dimerize to the distannylene upon crystallization: :2 R2Sn (R2Sn)2 Stannenes, compounds with tin–carbon double bonds, are exemplified by derivatives of stannabenzene. Stannoles, structural analogs of cyclopentadiene, exhibit little C-Sn double bond character.
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Furosemide has been reported to reversibly antagonize GABA-evoked currents of α6β2γ2 receptors at μM concentrations, but not α1β2γ2 receptors. During development, the α6β2γ2 receptor increases in expression in cerebellar granule neurons, corresponding to increased sensitivity to furosemide.
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Other viologens have been commercialized because they can change color reversibly many times through reduction and oxidation. The name viologen alludes to violet, one color it can exhibit, and the radical cation (C5H4NR)2+ is colored intensely blue.
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BET inhibitors are a class of drugs that reversibly bind the bromodomains of Bromodomain and Extra-Terminal motif (BET) proteins BRD2, BRD3, BRD4, and BRDT, and prevent protein-protein interaction between BET proteins and acetylated histones and transcription factors.
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To further reduce self-discharge and to reduce the vapor pressure of bromine, complexing agents are added to the positive electrolyte. These react reversibly with the bromine to form an oily red liquid and reduce the concentration in the electrolyte.
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Donepezil upregulates the nicotinic receptors in the cortical neurons, adding to neuroprotective property. It inhibits voltage-activated sodium currents reversibly and delays rectifier potassium currents and fast transient potassium currents, although this action is unlikely to contribute to clinical effects.
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For acetylcholine esterase (AChE), reversible inhibitors are those that do not irreversibly bond to and deactivate AChE. Drugs that reversibly inhibit acetylcholine esterase are being explored as treatments for Alzheimer's disease and myasthenia gravis, among others. Examples include tacrine and donepezil.
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There are mainly two types of ChIP, primarily differing in the starting chromatin preparation. The first uses reversibly cross-linked chromatin sheared by sonication called cross-linked ChIP (XChIP). Native ChIP (NChIP) uses native chromatin sheared by micrococcal nuclease digestion.
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The carbamate insecticide Carbaryl. The so-called carbamate insecticides feature the carbamate ester functional group. Included in this group are aldicarb (Temik), carbofuran (Furadan), carbaryl (Sevin), ethienocarb, fenobucarb, oxamyl, and methomyl. These insecticides kill insects by reversibly inactivating the enzyme acetylcholinesterase.
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This produces limitations that prevent the packing material from being changed or the column being regenerated. The approach they took to address those challenges meant incorporating TRP particles as a reversibly immobilized stationary phase. What separates this development from other AC methods is that the beads on which the modified TRP are attached can reversibly adhere to the inner surfaces of the microfluidic channels. The formulation of the smart bead matrix is a little complex, but in general PNIPAAm is modified two times, first with NHS, then with polyethylene glycol-biotin (PEG-b) resulting in PEG-b/pNIPAAm beads.
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Moreover, it was found that CB has an inhibitory effect on the uptake of sucrose-3H by chang- strain human liver cells and in CB-treated cells alterations in the appearance and location of microfilaments were observed. Furthermore, it was found that CB reversibly inhibits melanin granule movement in melanocytes. One year later, research on the influence of cytochalasin B on chloroplasts was done. It was found that the light-oriented movement of chloroplasts is reversibly inhibited by cytochalasin B. In 1973 researches found that cytochalasin B is a powerful non-competitive inhibitor of glucose transport.
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Since tubocurarine and the other components of curare bind reversibly to the ACh receptors, treatment for curare poisoning involves adding an acetylcholinesterase (AChE) inhibitor, which will stop the destruction of acetylcholine so that it can compete with curare. This can be done by administration of acetylcholinesterase (AChE) inhibitors such as pyridostigmine, neostigmine, physostigmine, and edrophonium. Acetylcholinesterase is an enzyme used to break down the acetylcholine (ACh) neurotransmitter left over in motor neuron synapses. The aforementioned inhibitors, termed "anticurare" drugs, reversibly bind to the enzyme's active site, prohibiting its ability to bind to its original target, ACh.
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In addition, androstenedione and testosterone can be converted into estrone and estradiol by aromatase, respectively. Prasterone is also reversibly transformed into prasterone sulfate by steroid sulfotransferase (specifically SULT1E1 and SULT2A1), which in turn can be converted back into prasterone by steroid sulfatase.
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Methods of oxygen storage for subsequent use span many approaches, including high pressures in oxygen tanks, cryogenics, oxygen-rich compounds and reaction mixtures, and chemical compounds that reversibly release oxygen upon heating or pressure change. O2 is the second most important industrial gas.
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Butantoxin (BuTX) is a compound of the venom of three Brazilian and an Argentinean scorpion species of the genus Tityus. Butantoxin reversibly blocks the voltage-gated K+ channels Shaker B and Kv1.2, and the Ca2+-activated K+ channels KCa 1.1 and KCa 3.1.
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Ptu1 is a toxin that can reversibly bind N-type calcium channels. Its isolated from the assassin bug Peirates turpis. The toxin belongs to the inhibitory cystine knot structural family (ICK) that has a core of disulfide bonds with four loops emerging from it.
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Antimony tetroxide is an inorganic compound with the formula Sb2O4. This material, which exists as the mineral cervantite, is white but reversibly yellows upon heating. The material, with empirical formula SbO2, is called antimony tetroxide to signify the presence of two kinds of Sb centers.
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CDK1 is necessary for the transition from G2 to M phase. RO-3306 is a selective CDK1 inhibitor that can reversibly arrest cells at the G2/M border. RO-3306 synchronized >95% of cycling cells (including cancer cells), and released cells rapidly enter mitosis.
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A halochromic material is a material which changes color when pH changes occur. The term ‘chromic’ is defined as materials that can change colour reversibly with the presence of a factor. In this case, the factor is pH. The pH indicators have this property.
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Specifically, salts of SH− break bonds between lignin and cellulose components of pulp in the Kraft process. Reversibly sodium sulfide in the presence of acids turns into hydrosulfides and hydrogen sulfide; this supplies hydrosulfides in organic solutions and is utilized in the production of thiophenol.
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Polypeptide toxins and many antibacterial peptides, such as colicins or hemolysins, and certain proteins involved in apoptosis, are sometimes considered a separate category. These proteins are water-soluble but can aggregate and associate irreversibly with the lipid bilayer and become reversibly or irreversibly membrane-associated.
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Phenoxyethanol is a vaccine preservative and potential allergen, which may result in a nodular reaction at the site of injection. It reversibly inhibits NMDAR-mediated ion currents. Ingestion may cause central nervous system and respiratory depression, vomiting and diarrhea in infants, particularly when combined with chlorphenesin.
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Cystamine has been shown to interact with DNA and reversibly bind to it. Furthermore, cystamine is also able to bind to nucleoproteins. The nucleic acids that form from binding to DNA are more stable then unbound nucleic acids. Binding of cystamine to nucleoproteins makes them precipitate.
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This hypothesis was later disproved, however, when in 1882 the German scientist Hermann von Helmholtz proved that affinity was not given by the heat evolved in a chemical reaction but rather by the maximum work, or free energy, produced when the reaction was carried out reversibly.
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Studies of fatty alcohol metabolism in fibroblasts suggest that very long-chain fatty alcohols, fatty aldehydes, and fatty acids are reversibly inter-converted in a fatty alcohol cycle. The metabolism of these compounds is impaired in several inherited human peroxisomal disorders, including adrenoleukodystrophy and Sjögren–Larsson syndrome.
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A molecular switch is a molecule that can be reversibly shifted between two or more stable states. The molecules may be shifted between the states in response to changes in pH, light, temperature, an electric current, microenvironment, or the presence of a ligand. Rotaxane based molecular shuttle.
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IUPAC stipulates that reversible- deactivation polymerization is a kind of chain polymerization, which is propagated by chain carriers that are deactivated reversibly, bringing them into active-dormant equilibria of which there might be more than one. An example of a reversible-deactivation polymerization is group-transfer polymerization.
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Pandinotoxins are the most potent inhibitors of the rapidly inactivating A-type voltage-gated potassium channels. They also block the delayed rectifier, slowly inactivating channels of the subfamily A member 2 (Kv1.2/KCNA2) [1] and they can reversibly block the shaker B potassium-channels (Kv1.1 sub-family).
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Naproxen works by reversibly inhibiting both the COX-1 and COX-2 enzymes as a non-selective coxib. This results in the inhibition of prostaglandin synthesis. Prostaglandins act as signaling molecules in the body, inducing inflammation. Thus, by inhibiting COX-1/2, naproxen induces an anti-inflammatory effect.
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The widely used herbicide paraquat is a viologen. This application is the largest consumer of this class of compounds. Viologens have been commercialized as electrochromic systems because of their ability to change color reversibly many times upon reduction and oxidation. In some applications, N-heptyl viologens are used.
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Inset, representative light- evoked single-unit response. Fig 2. Halorhodopsin (NpHR) rapidly and reversibly silences spontaneous activity in vivo in rat prelimbic prefrontal cortex. (Top left) Schematic showing in vivo green (532 nm) light delivery and single- unit recording of a spontaneously active CaMKllα::eNpHR3.0- EYFP expressing pyramidal neuron.
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In 2004, a novel electroactive polymer separator with the function of overcharge protection was first proposed by Denton and coauthors. This kind of separator reversibly switches between insulating and conducting states. Changes in charge potential drive the switch. More recently, separators primarily provide charge transport and electrode separation.
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11β-HSD also reversibly catalyzes the conversion of 7-ketocholesterol to 7-beta-hydroxycholesterol. Carbenoxolone is a modestly potent, reasonably effective, water-soluble blocker of gap junctions. Carbenoxolone has also been used in topical creams such as Carbosan gel, marketed for treatment of lip sores and mouth ulcers.
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Structures obtained in closed and open conformations are reversibly interconvertible by changes in the pH. A hydrogen-bonded perturbed pair of conserved aspartyl residues explains the pH dependence of this transition, and the pH regulates calcium influx in proteoliposomes. Homology models for human BI-1 provided insight into its cytoprotective activity.
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Sulfur monoxide (SO) converts to disulfur dioxide (S2O2) spontaneously and reversibly. So the substance can be generated by methods that produce sulfur monoxide. Disulfur dioxide has also been formed by an electric discharge in sulfur dioxide. Another laboratory procedure is to react oxygen atoms with carbonyl sulfide or carbon disulfide vapour.
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The globins are a superfamily of heme-containing globular proteins, involved in binding and/or transporting oxygen. These proteins all incorporate the globin fold, a series of eight alpha helical segments. Two prominent members include myoglobin and hemoglobin. Both of these proteins reversibly bind oxygen via a heme prosthetic group.
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The protein encoded by this gene is a cytoplasmic enzyme involved in cellular energy homeostasis. The encoded protein reversibly catalyzes the transfer of "energy-rich" phosphate between ATP and creatine and between phospho-creatine and ADP. Its functional entity is a MM-CK homodimer in striated (sarcomeric) skeletal and cardiac muscle.
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4-Hydroxy-2-oxopentanoaic acid, also known as 4-hydroxy-2-oxovalerate, is formed by the decarboxylation of 4-oxalocrotonate by 4-oxalocrotonate decarboxylase, is degraded by 4-hydroxy-2-oxovalerate aldolase, forming acetaldehyde and pyruvate and is reversibly dehydrated by 2-oxopent-4-enoate hydratase to 2-oxopent-4-enoate.
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Seattle: U of Washington, 2018. Web. Nanoparticles such as quantum dots may be able to increase the efficiency of light harvesting by regulating the wavelength and intensity of incoming light. The immediate applications of this research is the investigation of plasmonic nanoparticles.Samai, Soumyadyuti, and Ginger, David S. Reversibly Reconfigurable Plasmonic Nanomaterials.
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Some medications may reversibly affect hearing. These medications are considered ototoxic. This includes loop diuretics such as furosemide and bumetanide, non-steroidal anti-inflammatory drugs (NSAIDs) both over-the- counter (aspirin, ibuprofen, naproxen) as well as prescription (celecoxib, diclofenac, etc.), paracetamol, quinine, and macrolide antibiotics. Others may cause permanent hearing loss.
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The capsule has 20 well-defined pores with crown-ether functions which may be reversibly opened and closed. Substrates enter through these pores, and they can react to form a variety of species depending on the internal tapestry of the nanocontainer. This inorganic nanocell also allows ion transport through the cavity.
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At 573 °C at 1 atmosphere (and at higher temperatures and higher pressures) the α-quartz undergoes quartz inversion, transforms reversibly to β-quartz. The reverse process however is not entirely homogeneous and crystal twinning occurs. Care must be taken during manufacturing and processing to avoid phase transformation. Other phases, e.g.
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Graphene oxide can be reversibly reduced and oxidized via electrical stimulus. Controlled reduction and oxidation in two-terminal devices containing multilayer graphene oxide films are shown to result in switching between partly reduced graphene oxide and graphene, a process that modifies electronic and optical properties. Oxidation and reduction are related to resistive switching.
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The SBP-Tag has been used to reversibly immobilize recombinant proteins onto streptavidin- functionalized surfaces thereby permitting interaction assessment such as by surface plasmon resonance (SPR) techniques with re-use of the functionalized surface. SPR has also been used to compare the SBP-Tag with other streptavidin-binding peptides such as Strep-tag.
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5th Edition. (Houghton Mifflin Company) Thermodynamic processes can be carried out in one of two ways: reversibly or irreversibly. Reversibility means the reaction operates continuously at quasiequilibrium. In an ideal thermodynamically reversible process, the energy from work performed by or on the system would be maximized, and that from heat would be zero.
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The Community College of Baltimore County. Retrieved on July 31, 2009 (similarly to chloramphenicol) as well as inhibiting ribosomal translation. Another potential mechanism is premature dissociation of the peptidyl-tRNA from the ribosome. Macrolide antibiotics do so by binding reversibly to the P site on the 50S subunit of the bacterial ribosome.
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Several minerals and mineral-like materials reversibly bind CO2. Most often, these minerals are oxides or hydroxides, and often the CO2 is bound as carbonate. Carbon dioxide reacts with quicklime (calcium oxide) to form limestone (calcium carbonate), in a process called carbonate looping. Other minerals include serpentinite, a magnesium silicate hydroxide, and olivine.
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The cobratoxin of the Thailand cobra belongs to the neurotoxins. An important property of neurotoxins is that they are not usually able to cross the blood-brain barrier. Instead of this, they block the nerve transmission in the body. α-Cobratoxin is a post-synaptic neurotoxin, which reversibly blocks the nicotinic acetylcholine receptors.
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NTX blocks the pore of several types of voltage-gated K+ channels by reversibly binding to the channel receptor site. Furthermore, it affects calcium-activated potassium channels of skeletal muscles. In the squid axon, NTX was found to have relatively low binding affinity with their target site on the channel protein (KD = 300nM).
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These small molecules include signaling molecule and transcription factors. The size of the channel is also regulated to allow molecules up to 10,000 Da in size. The permeability of these channels is dependent on many factors, including Ca2+ concentration. An increase in cytosolic Ca2+ concentration will reversibly limit passage through the plasmodesmata.
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Ptu1 reversibly blocks N-type calcium channels. In addition, it has a low affinity for L or P/Q-type channels. The mechanism by which Ptu1 blocks N-type voltage dependent calcium channels is unknown. Since it has a structural similarity to the ω-conotoxins, it is possible that their blocking mechanism is similar.
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Tissue factor pathway inhibitor (or TFPI) is a single-chain polypeptide which can reversibly inhibit Factor Xa (Xa). While Xa is inhibited, the Xa-TFPI complex can subsequently also inhibit the FVIIa-tissue factor complex. TFPI contributes significantly to the inhibition of Xa in vivo, despite being present at concentrations of only 2.5 nM.
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The method of slipping is one which exploits the thermodynamic stability of the rotaxane. If the end groups of the dumbbell are an appropriate size it will be able to reversibly thread through the macrocycle at higher temperatures. By cooling the dynamic complex, it becomes kinetically trapped as a rotaxane at the lower temperature.
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ReplayGain is a standard for measuring and storing the loudness of an MP3 file (audio normalization) in its metadata tag, enabling a ReplayGain-compliant player to automatically adjust the overall playback volume for each file. MP3Gain may be used to reversibly modify files based on ReplayGain measurements so that adjusted playback can be achieved on players without ReplayGain capability.
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The stability of the Keggin structure allows the metals in the anion to be readily reduced. Depending on the solvent, acidity of the solution and the charge on the α-Keggin anion, it can be reversibly reduced in one- or multiple-electron steps.T. Okuhara; N. Mizuno; M. Misono. Advances in Cayalysis, Vol 41: Catalytic Chemistry of Heteropoly Compounds.
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On both sexes, only the atrophied forelegs lack claws. However, the male queen has a specialized patch of androconia, or a scent-pouch covered in scales, located on its dorsal hindwing. The position and structure of androconia is used to identify different genera. The male also has one reversibly extensible hair-pencil on each side of its abdomen.
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Somewhat like the parent amines, imines are mildly basic and reversibly protonate to give iminium salts. Iminium derivatives are particularly susceptible to reduction to the amines using transfer hydrogenation or by the stoichiometric action of sodium cyanoborohydride. Since imines derived from unsymmetrical ketones are prochiral, their reduction is a useful method for the synthesis of chiral amines.
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Dihydroxyacetone phosphate lies in the glycolysis metabolic pathway, and is one of the two products of breakdown of fructose 1,6-bisphosphate, along with glyceraldehyde 3-phosphate. It is rapidly and reversibly isomerised to glyceraldehyde 3-phosphate. The numbering of the carbon atoms indicates the fate of the carbons according to their position in fructose 6-phosphate.
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Con-G does not act directly at the glycine binding site. It can attenuate both the amplitude and the decay time constant of NMDA-mediated EPSCs and significantly and reversibly affect other different properties of NMDAR-mediated sEPSCs in cultured neurons. The effect of Con-G on the frequency of the sEPSCs most likely relates to antagonizing the NMDAR.
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The precise mechanism of action of tetrabenazine is unknown. Its anti-chorea effect is believed to be due to a reversible depletion of monoamines such as dopamine, serotonin, norepinephrine, and histamine from nerve terminals. Tetrabenazine reversibly inhibits vesicular monoamine transporter 2, resulting in decreased uptake of monoamines into synaptic vesicles, as well as depletion of monoamine storage.
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Zinc nitride reacts violently with water to form ammonia and zinc oxide. > Zn3N2 \+ 3H2O → 3ZnO + 2NH3 Zinc nitride reacts with lithium (produced in an electrochemical cell) by insertion. The initial reaction is the irreversible conversion into LiZn in a matrix of beta-Li3N. These products then can be converted reversibly and electrochemically into LiZnN and metallic Zn.
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Transferrins are glycoproteins found in vertebrates which bind to and consequently mediate the transport of Iron (Fe) through blood plasma. It is produced in the liver and contains binding sites for two Fe3+ atoms. Human transferrin is encoded by the TF gene and produced as a 76 kDa glycoprotein. Transferrin glycoproteins bind iron tightly, but reversibly.
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Research in the DeBeer group focuses on answering fundamental questions in energy research. Namely, how does one reversibly store and release energy from chemical bonds using earth abundant transition metals? And how is this done most efficiently? Her research group studies homogeneous, heterogeneous and biological catalysts in order to answer these questions, with a primary focus on enzymatic catalysis.
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This frees the active site lysine. 2\. S-adenosylmethionine is reversibly cleaved to the 5'-deoxyadenosyl radical through interactions with the enzyme's iron-sulfur cluster. 3\. A radical forms along with 5'-deoxyadenosyl, which remains bound to the active site. 4\. Isomerization of the original radical to a second and subsequent third form of the radial occurs. 5\.
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Malate dehydrogenase () (MDH) is an enzyme that reversibly catalyzes the oxidation of malate to oxaloacetate using the reduction of NAD+ to NADH. This reaction is part of many metabolic pathways, including the citric acid cycle. Other malate dehydrogenases, which have other EC numbers and catalyze other reactions oxidizing malate, have qualified names like malate dehydrogenase (NADP+).
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Slotoxin reversibly blocks the high conductance calcium-activated potassium channels composed of only α-subunits (Kd = 1.5 nM). Unreversibly blocks the high conductance calcium- activated potassium channels composed of α- and β1-subunits. Unreversibly and weakly blocks the high conductance calcium-activated potassium channels composed of α- and β4-subunits. It shows no activity on other potassium channels.
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PPIs were developed in the 1980s, with omeprazole being launched in 1988. Most of these medications are benzimidazole derivatives, related to omeprazole, but imidazopyridine derivatives such as tenatoprazole have also been developed. Potassium-competitive inhibitors such as revaprazan reversibly block the potassium-binding site of the proton pump, acting more quickly, but are not available in most countries.
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These sites are reversibly regulated by phosphatases such as, phosphatase calcineurin. Under periods of high electrical activity, depolarization of the neuron increases calcium influx and triggers phosphatase activity. Under resting conditions, KCNB1 tends to be phosphorylated. Phosphorylation raises the threshold voltage requirement for activation and allows microdomains to bind the channel, preventing KCNB1 from entering the plasma membrane.
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Tsumaki described the first metal–salen complexes in 1938. He found that the cobalt(II) complex Co(salen) reversibly binds O2, which led to intensive research on cobalt complexes of salen and related ligands for their capacity for oxygen storage and transport, looking for potential synthetic oxygen carriers. Cobalt salen complexes also replicate certain aspects of vitamin B12.
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Cocaine inhibits DAT function and vesicular dopamine transport (VMAT). Cocaine administration abruptly and reversibly increases both the Vmax of dopamine uptake and the Bmax of vesicular monoamine transporter 2 (VMAT-2) ligand (dihydrotetrabenazine) binding. Dopamine depletion resulting from administration of AMPT had similar neuropharmacological effects as cocaine. Administration of methamphetamine, a dopamine-releasing agent, rapidly decreased vesicular uptake.
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Trypanothione reductase with the lower molecule of an inhibitor bound irreversibly and the upper one reversibly. Created from PDB 1GXF. Diisopropylfluorophosphate (DFP) is shown as an example of an irreversible protease inhibitor in the figure above right. The enzyme hydrolyses the phosphorus–fluorine bond, but the phosphate residue remains bound to the serine in the active site, deactivating it.
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Streptolysin is a streptococcal hemolytic exotoxin. Types include streptolysin O (SLO), which is oxygen-labile, and streptolysin S (SLS), which is oxygen- stable. An antibody, antistreptolysin O, can be detected in an antistreptolysin O titre. Streptolysin O is hemolytically active only in a reversibly reduced state, unlike streptolysin S, which is stable in the presence of oxygen.
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Dioxygen complexes are coordination compounds that contain O2 as a ligand. The study of these compounds is inspired by oxygen-carrying proteins such as myoglobin, hemoglobin, hemerythrin, and hemocyanin. Several transition metals form complexes with O2, and many of these complexes form reversibly. The binding of O2 is the first step in many important phenomena, such as cellular respiration, corrosion, and industrial chemistry.
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It is soluble in a wide range of organic solvents. It is also moderately soluble in water, with which it reacts reversibly to form osmic acid (see below). Pure osmium(VIII) oxide is probably colourless and it has been suggested that its yellow hue is due to osmium dioxide (OsO2) impurities. The osmium tetroxide molecule is tetrahedral and therefore non-polar.
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Structured cellular materials can be remarkably strong despite very low density. Reversibly assembled cellular composite materials enable tailorable composite materials properties, to the ideal linear specific stiffness scaling regime. Using projection microstereolithography, octet microlattices have also been fabricated from polymers, metals, and ceramics. The design of the high performing lattices mean that the individual struts making up the materials do not bend.
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Tranexamic acid is a synthetic analog of the amino acid lysine. It serves as an antifibrinolytic by reversibly binding four to five lysine receptor sites on plasminogen. This reduces conversion of plasminogen to plasmin, preventing fibrin degradation and preserving the framework of fibrin's matrix structure. Tranexamic acid has roughly eight times the antifibrinolytic activity of an older analogue, ε-aminocaproic acid.
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The amount of work that must be done in order to transport reversibly and isothermally an infinitesimal quantity of water, identical in composition to the soil water, from a pool at atmospheric pressure and at the elevation of the point under consideration, to a similar pool at an external gas pressure of the point under consideration, divided by the volume of water transported.
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Mimosine is a plant amino acid that has been shown to reversibly inhibit progression beyond G1 phase in some human cells, including lymphoblastoid cells. Its proposed mechanism of action is an iron/zinc chelator that depletes iron within the cell. This induces double-strand breaks in the DNA, inhibiting DNA replication. This may involve blocking the action of an iron-dependent ribonucleotide reductase.
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All rhodopsins consist of two building blocks, a protein moiety and a reversibly covalently bound non-protein cofactor, retinal (retinaldehyde). The protein structure of rhodopsin consists of a bundle of seven transmembrane helices that form an internal pocket binding the photoreactive chromophore. They form a superfamily with other membrane-bound receptors containing seven transmembrane domains, for example odor and chemokine receptors.
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Asymmetric stereoinduction can be achieved with the use of chiral auxiliaries. Chiral auxiliaries may be reversibly attached to the substrate, inducing a diastereoselective reaction prior to cleavage, overall producing an enantioselective process. Examples of chiral auxiliaries include, Evans’ chiral oxazolidinone auxiliaries (for asymmetric aldol reactions)Evans, D. A.; Bartroli, J.; Shih, T. L., Am. Chem. Soc., 1981, 103, 2127-2129.
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Hop, occasionally written HOP, is an abbreviation for Hsp70-Hsp90 Organizing Protein. It functions as a co-chaperone which reversibly links together the protein chaperones Hsp70 and Hsp90. Hop belongs to the large group of co- chaperones, which regulate and assist the major chaperones (mainly heat shock proteins). It is one of the best studied co-chaperones of the Hsp70/Hsp90-complex.
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Each cell includes aligned fiber composite beams and looped fiber load-bearing holes that reversibly chain together to form volume-filling lattices. Mass-produced cells can be assembled to fill arbitrary structural shapes, with a resolution prescribed by the part scale that matches the variability of an application's boundary stress. The periodic nature of assemblies simplifies behavior analysis and prediction.
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Retrieved 14 March 2007. Climate adaptive building shells (CABS) can be identified as a sub-domain of responsive architecture, with special emphasis on dynamic features in facades and roofs. CABS can repeatedly and reversibly change some of its functions, features or behavior over time in response to changing performance requirements and variable boundary conditions, with the aim of improving overall building performance.
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The first isolated representatives were prepared from organotin halides or acids with orthometalated arylplatinum(II) compounds. The compound Me(PEt3)2PtOTf reacts reversibly with triflic acid between -60 and -80 °C, forming methane and (PEt3)2Pt(OTf)2 at -20 °C. Weak acids often suffice even water and alcohol and in C-H bond activation the proton source is an alkane.
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Lamin-B1 is a protein that in humans is encoded by the LMNB1 gene. The nuclear lamina consists of a two-dimensional matrix of proteins located next to the inner nuclear membrane. The lamin family of proteins make up the matrix and are highly conserved in evolution. During mitosis, the lamina matrix is reversibly disassembled as the lamin proteins are phosphorylated.
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The type locality is the Susanna Mine at Leadhills, Strathclyde, Scotland, UK. Leadhillite is a secondary mineral found in the oxidised zone of lead deposits associated with cerussite, anglesite, lanarkite, caledonite, linarite and pyromorphite. It may form pseudomorphs after galena or calcite, and conversely calcite and cerussite may form pseudomorphs after leadhillite. Heating leadhillite causes it to reversibly transform into susannite.
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Cimetidine is reported to be a competitive and reversible inhibitor of several CYP450 enzymes, although mechanism-based (suicide) irreversible inhibition has also been identified for cimetidine's inhibition of CYP2D6. It reversibly inhibits CYP450 enzymes by binding directly with the complexed heme-iron of the active site via one of its imidazole ring nitrogen atoms, thereby blocking the oxidation of other drugs.
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Generally, these materials reversibly change their shape/volume upon stimulation by the surrounding environments (the target analysts), which then leads to the variation of RI or absorption of the sensing materials. Consequently, the surrounding changes will be recorded and interrogated by the optical fibers, realizing sensing functions of optical fibers. Currently, various fiber-optic chemical sensors and biosensors have been proposed and demonstrated.
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Local anesthetic agents prevent transmission of nerve impulses without causing unconsciousness. They act by reversibly binding to fast sodium channels from within nerve fibers, thereby preventing sodium from entering the fibres, stabilising the cell membrane and preventing action potential propagation. Each of the local anesthetics have the suffix "–caine" in their names. Local anesthetics can be either ester- or amide-based.
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Rubrene, like other polycyclic aromatic molecules, undergoes redox reactions in solution. It oxidizes and reduces reversibly at 0.95 V and −1.37 V, respectively vs SCE. When the cation and anion are co-generated in an electrochemical cell, they can combine with annihilation of their charges, but producing an excited rubrene molecule that emits at 540 nm. This phenomenon is called electrochemiluminescence.
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Human and selected bacterial GALE isoforms bind UDP-GlcNAc, reversibly catalyzing its conversion to UDP-GalNAc. A family of glycosyltransferases known as UDP-N- acetylgalactosamine:polypeptide N-acetylgalactosamine transferases (ppGaNTases) transfers GalNAc from UDP-GalNAc to glycoprotein serine and threonine residues. ppGaNTase-mediated glycosylation regulates protein sorting, ligand signaling, resistance to proteolytic attack, and represents the first committed step in mucin biosynthesis.
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DsbB contains 4 essential cysteine residues, reversibly forming two disulfide bonds. Although DsbA displays no proofreading activity for repair of wrongly paired disulfides, DsbC, DsbE and DsbG have been found to demonstrate proofreading activity. Therefore, the two transmembrane pathways involving DsbD and DsbB together catalyze extracellular disulfide reduction (DsbD) and oxidation (DsbB) in a superficially reversible process that allows dithiol/disulfide exchange.
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It has a low melting and boiling point. It is mainly produced and consumed in the production of aluminium metal, but large amounts are also used in other areas of the chemical industry. The compound is often cited as a Lewis acid. It is an example of an inorganic compound that reversibly changes from a polymer to a monomer at mild temperature.
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HTX is a voltage-gated K+ channel blocker peptide. It reversibly blocks type Kv1.1, Kv1.2 and Kv1.3 channels with IC50 values of 13, 16 and 2 nM, respectively. HTX has a different affinity for K+ channels. It appears to be 20 times less potent on Kv1.2 channels and 90 times more potent on Kv1.3 channels than the α-KTx6 family member MTX.
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It swims using a single sheathed polar flagellum with a characteristic dampened filament waveform. Bdellovibrio attacks other Gram-negative bacteria by attaching itself to the prey cell's outer membrane and peptidoglycan layer, after which it creates a small hole in the outer membrane. The Bdellovibrio cell then enters the host periplasmic space. It remains reversibly attached to it for a short "recognition" period.
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Four of these oxygen atoms originate from four different carboxylate groups and the remaining two oxygen atoms belong to two different μ-OH moieties, which bridge neighboring metal centers. The resulting framework structure contains one-dimensional diamond- shaped pores. Many research group have investigated the flexibility of the MIL-53 structure. This flexible behavior, during which the pore cross-section changes reversibly, was termed 'breathing.
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For example, it oxidatively adds H2 to give a dihydride. He subsequently discovered that his complex reversibly bound O2, which was then a startling achievement. He discovered the main reactions of oxidative addition, a process that is central to homogeneous catalysis in organometallic chemistry. He demonstrated a number of important substituent effects on the oxidative addition, such as the greater reactivity of Ir(I) vs.
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Water free chloroacetaldehyde is prepared from the hydrate by azeotropic distillation with chloroform, toluene or carbon tetrachloride. Anhydrous chloroacetaldehyde reversibly converts to polyacetals. Less reactive chloroacetaldehyde derivatives might be used instead to obtain chloroacetaldehyde or bypass its intermediate formation completely: e.g. chloroacetaldehyde dimethyl acetal (2-chloro-1,1-dimethoxyethane) hydrolyzes in acidic conditions to give chloroacetaldehyde, which may then quickly react with the other reagents instead of polymerizing.
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Since they are noncovalently bound to the fibrils, they may reversibly associate and disassociate so that the bridges between fibrils can be broken and reformed. This process may be involved in allowing the fibril to elongate and decrease in diameter under tension.Cribb, A. M.; Scott, J.E. (1995). In Tendon response to tensile-stress - an ultrastructural investigation of collagen - proteoglycan interactions in stressed tendon,1995; Cambridge Univ Press.
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Once it reaches the second piston, the entire piston-cylinder arrangement moves at a constant velocity up. #The kinetic energy produced during the first process is converted into external work. #Adiabatical expansion: The gaseous detonation products return to a final pressure equal to the initial pressure, Ρ0. #Heat extraction: The gaseous products are reversibly cooled at a constant pressure to reach the initial temperature Τ0.
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Due to the role of protein disulfide-isomerase in a number of disease states, small molecule inhibitors of protein disulfide-isomerase have been developed. These molecules can either target the active site of protein disulfide-isomerase irreversibly or reversibly. It has been shown that protein disulfide-isomerase activity is inhibited by red wine and grape juice, which could be the explanation for the French paradox.
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One of the more recent techniques identified to synthesis PTMA is a type of free radical polymerization known as reversibly addition-fragmentation chain transfer (RAFT) mediated polymerization.Rostro, L.; Baradwaj, A. G.; Boudouris, B. W. ACS Appl. Mater. Interfaces 2013, 5 (20), 9896–9901. doi: 10.1021/am403223s RAFT mediated polymerization of TEMPO RAFT-mediated polymerization of PTMA utilizes the same starting monomer as free-radical polymerization.
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Applied and Environmental Microbiology, 79(16), 4895–4905. By measuring the adhesion of single cells, important information for different topics in biology and materialscience can be obtained. With FluidFM it is possible to increase the rate in which these experiments can be performed, and even to assess the adhesion of spread cells. The cell of interest is reversibly attached to the probe by applying an underpressure.
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The rate in which these experiments can be performed is rather low because normally colloids have to be pre-glued on an AFM probe. In contrast, the colloid probes can be reversibly attached to the FluidFM probe by underpressure. Therefore, one probe can be used for many experiments and many colloids.2015\. B. R. Simona, L. Hirt, L. Demkó, T. Zambelli, J. Vörös, M. Ehrbar & V. Milleret.
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Carvedilol is both a non-selective beta adrenergic receptor blocker (β1, β2) and an alpha adrenergic receptor blocker (α1). The S(-) enantiomer accounts for the beta blocking activity whereas the S(-) and R(+) enantiomer have alpha blocking activity. Carvedilol reversibly binds to beta adrenergic receptors on cardiac myocytes. Inhibition of these receptors prevents a response to the sympathetic nervous system, leading to decreased heart rate and contractility.
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In order to avoid this issue, several microbes have evolved to make symbiosis with eukaryotic hosts. In fact, R. pachyptila is able to cover the oxic and anoxic areas to get both sulfide and oxygen. Thanks to its hemoglobin that can bind sulfide reversibly and apart from oxygen by means of two cysteine residues, and then transport it to the trophosome, where bacterial metabolism can occur.
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This release is controlled by either a chemical or physiological trigger. Linear and matrix smart polymers exist with a variety of properties depending on reactive functional groups and side chains. These groups might be responsive to pH, temperature, ionic strength, electric or magnetic fields, and light. Some polymers are reversibly cross-linked by noncovalent bonds that can break and reform depending on external conditions.
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HAE is caused by a mutation of the C1-inhibitor gene. Defective or missing C1-inhibitor permits activation of kallikrein, a protease that is responsible for liberating bradykinin from its precursor kininogen. An excess of bradykinin leads to fluid leakage from blood vessels, causing swelling of tissues typical of HAE. Ecallantide suppresses this pathogenetic mechanism by selectively and reversibly inhibiting the activity of plasma kallikrein.
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In the first, the substrate binds reversibly to the enzyme, forming the enzyme- substrate complex. This is sometimes called the Michaelis–Menten complex in their honor. The enzyme then catalyzes the chemical step in the reaction and releases the product. This work was further developed by G. E. Briggs and J. B. S. Haldane, who derived kinetic equations that are still widely used today.
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HOCl is the most potent oxidant generated by neutrophils, and can cause significant tissue damage during inflammation. Dapsone arrests myeloperoxidase in an inactive intermediate form, reversibly inhibiting the enzyme. This prevents accumulation of hypochlorous acid, and reduces tissue damage during inflammation. Myeloperoxidase inhibition has also been suggested as a neuron-sparing mechanism for reducing inflammation in neurodegenerative diseases such as Alzheimer's disease and stroke.
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A high nitric oxide concentration, such as one added exogenously to the enzyme, reverses cyanide inhibition of COX. Nitric oxide can reversibly bind to either metal ion in the binuclear center to be oxidized to nitrite. NO and CN- will compete with oxygen to bind at the site, reducing the rate of cellular respiration. Endogenous NO, however, which is produced at lower levels, augments CN- inhibition.
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The body's acid–base balance is tightly regulated. Several buffering agents exist which reversibly bind hydrogen ions and impede any change in pH. Extracellular buffers include bicarbonate and ammonia, while proteins and phosphate act as intracellular buffers. The bicarbonate buffering system is especially key, as carbon dioxide (CO2) can be shifted through carbonic acid (H2CO3) to hydrogen ions and bicarbonate (HCO3−) as shown below.
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In addition, minor variations in each receptor have been identified. Cannabinoids bind reversibly and stereo-selectively to the cannabinoid receptors. Subtype selective cannabinoids have been developed which theoretically may have advantages for treatment of certain diseases such as obesity. It appears that cannabinoid receptors are unique to the phylum Chordata and, as such, they have a rather restricted phylogenetic distribution in the animal kingdom.
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When there are low levels of Ca2+ concentrations, GAP-43 is able to bind and stabilize the inactive Ca2+ -free state of calmodulin, this allows it to absorb and reversibly inactivate the CaM in the growth cones. This binding of the calmodulin to GAP-43 is allowed by the negatively charged CaM electrostatically interacting with the positively charged “pocket” formed in the GAP-43 molecule itself.
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Aqueous vanadate (V) compounds undergo various self-condensation reactions. Depending on pH, major vanadate anions in solution include VO2(H2O)42+, VO43−, V2O73−, V3O93−, V4O124−, and V10O266−. The anions often reversibly protonate. Decavanadate forms according to this equilibrium: :H3V10O283− ⇌ H2V10O284− \+ H+ :H2V10O284− ⇌ HV10O285− \+ H+ :HV10O285−(aq) ⇌ V10O286− \+ H+ The structure of the various protonation states of the decavanadate ion has been examined by 51V NMR spectroscopy.
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Carbenoxolone (CBX) is a glycyrrhetinic acid derivative with a steroid-like structure, similar to substances found in the root of the licorice plant. Carbenoxolone is used for the treatment of peptic, esophageal and oral ulceration and inflammation. Electrolyte imbalance is a serious side effect of carbenoxolone when used systemically. Carbenoxolone reversibly inhibits the conversion of inactive cortisone to cortisol by blocking 11β-hydroxysteroid dehydrogenase (11β-HSD).
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Eptifibatide (Integrilin, Millennium Pharmaceuticals, also co-promoted by Schering-Plough/Essex), is an antiplatelet drug of the glycoprotein IIb/IIIa inhibitor class. Eptifibatide is a cyclic heptapeptide derived from a disintegrin protein () found in the venom of the southeastern pygmy rattlesnake (Sistrurus miliarius barbouri). It belongs to the class of the arginin-glycin-aspartat-mimetics and reversibly binds to platelets. Eptifibatide has a short half-life.
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Butantoxin blocks the K+ channels reversibly, following Michaelis–Menten saturation kinetics. The toxin binds to the external vestibule of the pore, occluding it. This reaction is governed by electrostatic interactions between negatively charged residues in the K+ channel and positively charged residues in the toxin. Based on the results obtained from docking simulations, butantoxin may require only 6 main molecular contacts to interact with the Kv1.2 channel.
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Ambenonium exerts its actions against myasthenia gravis by competitive reversible inhibition of acetylcholinesterase, the enzyme responsible for the hydrolysis of acetylcholine. Myasthenia gravis occurs when the body produces antibodies against acetylcholine receptors, and thus inhibits signal transmission across the myoneural junction. Ambenonium reversibly binds acetylcholinesterase, inactivates it and therefore increases levels of acetylcholine. This, in turn, facilitates transmission of impulses across the myoneural junction and effectively treats the disease.
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The thiol-based polymers have disulfide bonds that can be reversibly cross-linked through oxidation and reduction. Under reducing condition, the disulfide (SS) bridges in the polymer breaks and results in monomers, however, under oxidizing condition, the thiols (SH) of each monomer forms the disulfide bond, cross-linking the starting materials to form the polymer. Chujo et al. have shown the thiol-based reversible cross-linked polymer using poly(N-acetylethyleneimine).
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Electrophysiological experiments (whole cell configuration patch clamping) have been performed to investigate the physiological effect of HgeTx1 on Shaker B K+-channels in insect cell cultures. These recordings show that HgeTx1 reversibly blocks the Shaker B K+-channel. This blockage follows a Michaelis-Menten saturation relationship with a Kd of 52 nM. However, there is no report of selectivity for or blockage of other subtypes of K+-channels.
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The ability of aptamers to reversibly bind molecules such as proteins has generated increasing interest in using them to facilitate controlled release of therapeutic biomolecules, such as growth factors. This can be accomplished by tuning the affinity strength to passively release the growth factors, along with active release via mechanisms such as hybridization of the aptamer with complementary oligonucleotides or unfolding of the aptamer due to cellular traction forces.
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Some [NiFe]-containing proteins are known to sense H2 and thus regulate transcription. Copper- containing proteins are known to sense ethylene, which is known to be a hormone relevant to the ripening of fruit. This example illustrates the essential role of organometallic chemistry in nature, as few molecules outside of low-valent transition metal complexes reversibly bind alkenes. Cyclopropenes inhibit ripening by binding to the copper(I) center.
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On the other hand, novel drugs like ticagrelor (Brilinta®) and cangrelor (Kengrexal®) are non-thienopyridines and reversibly inhibit P2Y12 meaning they act directly on the receptor without the requirement of metabolic activation and display faster onset and offset of action. These drugs are frequently administrated in combination with aspirin (acetylsalicylic acid) to enhance platelet inhibition especially in patients with ACS or undergoing percutaneous coronary intervention (PCI).
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In pharmacology and medicine vectorization of drugs refers to (intracellular) targeting with plastic, noble metal or silicon nanoparticles or liposomes to which pharmacologically active substances are reversibly bound or attached by adsorption. CNRS researchers have devised a way to overcome the problem of multidrug resistance using polyalkylcyanoacrylate (PACA) nanoparticles as "vectors". Drug nanocarriers are expected to play a major role in delivering multiple drugs to tumor tissues by overcoming biological barriers.
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PYP was first discovered in 1985. A recently (2016) developed chemogenetic system named FAST (Fluorescence-Activating and absorption Shifting Tag) was engineered from PYP to specifically and reversibly bind a series of hydroxybenzylidene rhodanine (HBR) derivatives for their fluorogenic properties. Upon interaction with FAST, the fluorogen is locked into a fluorescent conformation unlike when in solution. This new protein labelling system is used in a variety of microscopy and cytometry setups.
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Control of cluster size for in the aggregation of Janus nanoparticles has also been demonstrated. Lattuada et al. achieved control of the cluster size of Janus particles with one face PAA and the other either PDMAEMA or PNIPAm by mixing small amounts of these Janus nanoparticles with PAA-coated particles. One unique feature of these clusters was stable particles could be recovered reversibly when high pH conditions were restored.
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However, it does not form stable aqueous solutions, due in part to its autopolymerisation, and its tendency to be oxidised by water. Copper hydride reversibly precipitates from pyridine solution, as an amorphous solid. However, repeated dissolution affords the regular crystalline form, which is insoluble. Under standard conditions, molecular copper hydride autopolymerises to form the crystalline form, including under aqueous conditions, hence the aqueous production method devised by Wurtz.
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The dimeric titanium(III) complex reversibly dissociates to the monomer Cp2TiCl. This 15 electron species is Lewis acidic and thus binds epoxides and carbonyl compounds. The complex transfers a single electron to the coordinated substrate generating an alkyl centered radical and an oxygen bound titanium(IV) species. This process is driven by the strength of the titanium- oxygen bond, as well as strain release in the case of epoxides.
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The dressing's mode of action relies on the ability of the polymers to sense and adapt to the changing humidity and fluid content in all areas of the wound simultaneously and to automatically and reversibly switch from absorption to hydration. The smart polymer action ensures the active synchronized response of the dressing material to changes in and around the wound to support the optimal moist healing environment at all times.
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The four phosphorus atoms are at the corners of a tetrahedron surrounding the palladium(0) center. This structure is typical for four-coordinate 18 e− complexes. The corresponding complexes Ni(PPh3)4 and Pt(PPh3)4 are also well known. Such complexes reversibly dissociate PPh3 ligands in solution, so reactions attributed to Pd(PPh3)4 often in fact arise from Pd(PPh3)3 or even Pd(PPh3)2.
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Reversible inhibitors of monoamine oxidase A (RIMAs) are a subclass of MAOIs that selectively and reversibly inhibit the MAO-A enzyme. RIMAs are used clinically in the treatment of depression and dysthymia. Due to their reversibility, they are safer in single-drug overdose than the older, irreversible MAOIs, and weaker in increasing the monoamines important in depressive disorder. RIMAs have not gained widespread market share in the United States.
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Epicocconone is long Stokes' shift fluorescent dye found in the fungus Epicoccum nigrum. Though weakly fluorescent in water (green emission, 520 nm) it reacts reversibly with proteins to yield a product with a strong orange-red emission (610 nm). This dye can be used as a sensitive total protein stain for 1D and 2D electrophoresis, quantitative determination of protein concentration, making it a powerful loading control for Western blots.
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The slider constrains the teeth positions, moves them along a given path, and acts on the teeth one-by-one in its "Y-shaped channel" and so can reversibly lock and unlock them. This is a lock and key design. In Sundback's invention the teeth are symmetric with "exterior and interior rounded surfaces" that are "elongated transversely". The teeth have a material part ("external projection") and a space ("internal recess").
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Lactoferrin belongs to the basic proteins, its isoelectric point is 8.7. It exists in two forms: iron-rich hololactoferrin and iron-free apolactoferrin. Their tertiary structures are different; apolactoferrin is characterized by "open" conformation of the N-lobe and the "closed" conformation of the C-lobe, and both lobes are closed in the hololactoferrin. Each lactoferrin molecule can reversibly bind two ions of iron, zinc, copper or other metals.
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Eptifibatide was modeled after a component in southeastern pygmy rattlesnake venom and is used in anticoagulation therapies in an effort to reduce the risk of heart attacks; it is used in only severe cases because of the possible side effect of thrombocytopenia, a condition where platelets are unable to aggregate at all. Eptifibatide binds reversibly to platelets reducing the risk of thrombosis. It is an antagonist of glycoprotein IIb/IIIa.
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The product of this gene is an epsilon subunit of coatomer protein complex. Coatomer is a cytosolic protein complex that binds to dilysine motifs and reversibly associates with Golgi non-clathrin-coated vesicles. It is required for budding from Golgi membranes, and is essential for the retrograde Golgi-to-ER transport of dilysine-tagged proteins. Coatomer complex consists of at least the alpha, beta, beta', gamma, delta, epsilon and zeta subunits.
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Some medications may reversibly affect hearing. These medications are considered ototoxic. This includes loop diuretics such as furosemide and bumetanide, non- steroidal anti-inflammatory drugs (NSAIDs) both over-the-counter (aspirin, ibuprofen, naproxen) as well as prescription (celecoxib, diclofenac, etc.), paracetamol, quinine, and macrolide antibiotics. The link between NSAIDs and hearing loss tends to be greater in women, especially those who take ibuprofen six or more times a week.
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Many models of myoglobin have been synthesized as part of a broad interest in transition metal dioxygen complexes. A well known example is the picket fence porphyrin, which consists of a ferrous complex of a sterically bulky derivative of tetraphenylporphyrin. In the presence of an imidazole ligand, this ferrous complex reversibly binds O2. The O2 substrate adopts a bent geometry, occupying the sixth position of the iron center.
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A molecular switch is a molecule that can be reversibly shifted between two or more stable states.Molecular Machines & Motors (Structure and Bonding) J.-P. Sauvage Ed. The molecules may be shifted between the states in response to environmental stimuli, such as changes in pH, light, temperature, an electric current, microenvironment, or in the presence of ions and other ligands. In some cases, a combination of stimuli is required.
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In one study a vanadium pentoxide surface is presented that can switch reversibly between superhydrophobicity and superhydrophilicity under the influence of UV radiation. According to the study any surface can be modified to this effect by application of a suspension of rose-like V2O5 particles for instance with an inkjet printer. Once again hydrophobicity is induced by interlaminar air pockets (separated by 2.1 nm distances). The UV effect is also explained.
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The role of the NET in many brain disorders underlies the importance of understanding the (dys)regulation of the transporter. A complete model of the proteins that associate with the transporter will be useful in designing drug therapies for diseases such as schizophrenia, affective disorder, and autonomic disorders. Recently discovered mechanisms of the NET, including the ability to act reversibly and as an ion channel, provide other areas of research.
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285, 6-9. 12 In general, the mechanism is thought to proceed via the transfer of neutral hydrogen atoms to the support upon overcoming an activation energy barrier. This has even been observed at temperatures as low as 180K in metal-organic framework (MOF) catalysts laced with Palladium nanoparticles (PdnP’s). Upon transfer to the support, they assume the role of Lewis bases where they donate electrons and reversibly reduce the sorbent.
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21-Deoxycortisone, also known as 21-desoxycortisone, 11-keto-17α-hydroxyprogesterone, or 17α-hydroxypregn-4-ene-3,11,20-trione, is a naturally occurring, endogenous steroid and minor intermediate and metabolite in corticosteroid metabolism. It is related to 21-deoxycortisol (11β,17α-dihydroxyprogesterone) and is reversibly formed from it by 11β-hydroxysteroid dehydrogenase, analogously to the reversible formation of cortisone from cortisol. 21-Deoxycortisone can be transformed into cortisone by 21-hydroxylase.
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Researchers conjugated the thermo-responsive polymer poly(N-isopropylacrylamide) (pNIPAm) with the biotin-recognizing protein streptavidin close to its recognition site. At temperatures above the lower critical solution temperature (LCST), the polymer collapses and blocks the binding site, thus reversibly preventing biotin from binding to streptavidin. By copolymerization with two different thermosensitive polymers poly(sulfobetaine methacrylamide) (pSBAm) and pNIPAm together, researchers can control enzyme activity in a small temperature window.
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Gimeracil inhibits the degradation of fluorouracil by reversibly blocking the dehydrogenase enzyme dihydropyrimidine dehydrogenase (DPD). This results in higher 5-FU levels and a prolonged half-life of the substance. Oteracil mainly stays in the gut because of its low permeability, where it reduces the production of 5-FU by blocking the enzyme orotate phosphoribosyltransferase. Lower 5-FU levels in the gut result in a lower gastrointestinal toxicity.
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ESP15228, the (also) active metabolite Following oral intake, bempedoic acid reaches highest blood plasma concentrations after 3.5 hours. Food does not affect its absorption. When in the bloodstream, 99.3% of the substance are bound to plasma proteins. About a fifth of the substance is reversibly converted by an aldo-keto reductase enzyme to a metabolite (called ESP15228) that is also pharmacologically active in form of its coenzyme A–thioester.
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Acetoacetyl-CoA briefly combines with another acetyl-CoA via HMG-CoA synthase to form hydroxy-β-methylglutaryl-CoA. Hydroxy- β-methylglutaryl-CoA form the ketone body acetoacetate via HMG-CoA lyase. Acetoacetate can then reversibly convert to another ketone body—D-β- hydroxybutyrate—via D-β-hydroxybutyrate dehydrogenase. Alternatively, acetoacetate can spontaneously degrade to a third ketone body (acetone) and carbon dioxide, which generates much greater concentrations of acetoacetate and D-β-hydroxybutyrate.
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This can be done in two general ways: reversibly (namely, using unitary operations) or irreversibly (for example, using a heat bath). Algorithmic cooling is the name of a family of algorithms that are given a set of qubits and purify (cool) a subset of them to a desirable level. This can also be viewed in a probabilistic manner. Since qubits are two-level systems, they can be regarded as coins, unfair ones in general.
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In the first, the substrate binds reversibly to the enzyme, forming the enzyme-substrate complex. This is sometimes called the Michaelis complex. The enzyme then catalyzes the chemical step in the reaction and releases the product. The kinetics of many enzymes is adequately described by the simple Michaelis-Menten model, but all enzymes have internal motions that are not accounted for in the model and can have significant contributions to the overall reaction kinetics.
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This involves the austenite/martensite phase transformation between a face-centered crystal lattice (FCC) and a body-centered tetragonal crystal structure (BCT). Superelastic alloys belong to the larger family of shape-memory alloys. When mechanically loaded, a superelastic alloy deforms reversibly to very high strains (up to 10%) by the creation of a stress-induced phase. When the load is removed, the new phase becomes unstable and the material regains its original shape.
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The regulation of these phosphorylations and the consequences for the association of transcription factors plays a major role in the regulation of transcription. During the transcription cycle, the CTD of the large subunit of RNAP II is reversibly phosphorylated. RNAP II containing unphosphorylated CTD is recruited to the promoter, whereas the hyperphosphorylated CTD form is involved in active transcription. Phosphorylation occurs at two sites within the heptapeptide repeat, at Serine 5 and Serine 2.
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Just as importantly, the existence of an accessible screen — a two-dimensional display of text that could be rapidly and reversibly modified — made it economical for software designers to deploy interfaces that could be described as visual rather than textual. The pioneering applications of this kind were computer games and text editors; close descendants of some of the earliest specimens, such as rogue(6), and vi(1), are still a live part of Unix tradition.
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This means that less of the intended substrate will bind to the enzyme, resulting in less product being formed. In addition, the substrate analog may also be missing chemical components that allow the enzyme to go through with its reaction. This also causes the amount of product created to decrease. Substrate analogs bind to the binding site reversibly. This means that the binding of the substrate analog to the enzyme’s binding site is non-permanent.
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Sodium nitroprusside spectrum is used to calibrate Mössbauer spectrometers Sodium nitroprusside is often used as a reference compound for the calibration of Mössbauer spectrometers. Sodium nitroprusside crystals are also of interest for optical storage. For this application, sodium nitroprusside can be reversibly promoted to a metastable excited state by blue-green light, and de-excited by heat or red light. In physiology research, sodium nitroprusside is frequently used to test endothelium-independent vasodilation.
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Nucleoporins regulate the transport of macromolecules through the nuclear envelope via interactions with the transporter molecules karyopherins. Karyopherins will bind to their cargo, and reversibly interact with the FG-repeats in nucleoporins. Karyopherins and their cargo are passed between FG-repeats until they diffuse down their concentration gradient and through the nuclear pore complex. Karyopherins can serve as an importin (transporting proteins into the nucleus) or an exportin (transporting proteins out of the nucleus).
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The advancing front represents a zone of demineralized dentin due to acid and has no bacteria present. The zones of bacterial penetration and destruction are the locations of invading bacteria and ultimately the decomposition of dentin. The zone of destruction has a more mixed bacterial population where proteolytic enzymes have destroyed the organic matrix. The innermost dentin caries has been reversibly attacked because the collagen matrix is not severely damaged, giving it potential for repair.
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Estriol 3-glucuronide, or oestriol 3-glucuronide, also known as estriol 3-β-D- glucosiduronic acid, is a natural, steroidal estrogen and a glucuronic acid (β-D-glucopyranuronic acid) conjugate of estriol. It is found in the urine of women as a reversibly formed metabolite of estriol. The positional isomer of estriol 3-glucuronide, estriol 16α-glucuronide, also occurs as an endogenous metabolite of estriol, but to a much greater extent in comparison.
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It is of foremost importance for these sodium channels to function properly, as they are essential for the propagation of an action potential. Without this ability, the nerve cell becomes unable to transmit signals and the region of the body that it enervates is cut off from the nervous system. This may lead to paralysis of the affected region, as in the case of saxitoxin. Saxitoxin binds reversibly to the sodium channel.
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The inner surface of the microfluidic channels is composed of polyethylene terephthalate, to which the PEG-b/pNIPAAm beads reversibly bind above the LCST. When the sample solution is passed through the channels, the target analyte binds to the biotin ligand. The temperature can then be brought below the LCST to dissociate and become removed from the inner channels. This allows for a system adept to being reloaded with stationary phase under mild conditions.
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This is completely harmless, but patients must be warned about this to avoid unnecessary concern. When iron supplements are given in a liquid form, teeth may reversibly discolor (this can be avoided through the use of a straw). Intramuscular injection can be painful, and brown discoloration may be noticed. Treatments with iron(II) sulfate have higher incidence of adverse events than iron(III)-hydroxide polymaltose complex (IPC) or iron bis- glycinate chelate.
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Cross-linked ChIP is mainly suited for mapping the DNA target of transcription factors or other chromatin-associated proteins, and uses reversibly cross-linked chromatin as starting material. The agent for reversible cross-linking could be formaldehyde or UV light. Then the cross-linked chromatin is usually sheared by sonication, providing fragments of 300 - 1000 base pairs (bp) in length. Mild formaldehyde crosslinking followed by nuclease digestion has been used to shear the chromatin.
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Most competitive inhibitors function by binding reversibly to the active site of the enzyme. As a result, many sources state that this is the defining feature of competitive inhibitors. This, however, is a misleading oversimplification, as there are many possible mechanisms by which an enzyme may bind either the inhibitor or the substrate but never both at the same time. For example, allosteric inhibitors may display competitive, non- competitive, or uncompetitive inhibition.
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Thiomers are able to reversibly open tight junctions. The responsible mechanism seems to be based on the inhibition of protein tyrosine phosphatase being involved in the closing process of tight junctions. Due to thiolation the permeation enhancing effect of polymers such as polyacrylic acid or chitosan can be up to 10-fold ımproved. In comparison to most low molecular weight permeation enhancers, thiolated polymers offer the advantage of not being absorbed from the mucosal membrane.
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The device operated with nearly 100% coulombic efficiency at both low (0.15 C) and high (4.5 C) discharge and charge rates. In September 2017, researchers stated they were able to raise the voltage to 4.0 volts. In May 2019, researchers published an article where the voltage increased to 4.2 volts. High specific capacity from a densely packed stage-I graphite intercalation compound of C3.5[Br0.5Cl0.5] can form reversibly in water-in-bisalt electrolyte.
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While competitive antagonists bind to the agonist or ligand binding site of the receptor reversibly, non-competitive antagonists can either bind to the ligand site or other site called the allosteric site. A receptor's agonist does not bind to its allosteric binding site. The binding of a non-competitive antagonist is irreversible. If the non- competitive antagonist binds to the allosteric site and an agonist binds to the ligand site, the receptor will remain unactivated.
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Potassium is vital in the human body, and potassium chloride by mouth is the common means to treat low blood potassium, although it can also be given intravenously. It is on the World Health Organization's List of Essential Medicines. Overdose causes hyperkalemia which can disrupt cell signaling to the extent that the heart will stop, reversibly in the case of some open heart surgeries, or to induce death in the case of lethal injections.
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Hemocyanins (also spelled haemocyanins and abbreviated Hc) are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a single oxygen molecule (O2). They are second only to hemoglobin in frequency of use as an oxygen transport molecule. Unlike the hemoglobin in red blood cells found in vertebrates, hemocyanins are not bound to blood cells but are instead suspended directly in the hemolymph.
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Terbium(III,IV) oxide loses O2 when heated at high temperatures; at more moderate temperatures (ca. 350 °C) it reversibly loses oxygen, as shown by exchange with18O2. This property, also seen in Pr6O11 and V2O5, allows it to work like V2O5 as a redox catalyst in reactions involving oxygen. It was found as early as 1916 that hot Tb4O7 catalyses the reaction of coal gas (CO + H2) with air, leading to incandescence and often ignition.
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The α form is defined as the standard state of the element, but is actually metastable under standard conditions. It has a body-centered cubic crystal structure, and transforms reversibly into the β form at 195.2 K. The β form is believed to have a hexagonal crystal structure. White phosphorus is a translucent waxy solid that quickly becomes yellow when exposed to light. For this reason it is also called yellow phosphorus.
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In animal studies, GTx-758 reversibly suppresses testosterone concentrations to castrate levels, reduces prostate size and levels of prostate-specific antigen (PSA), but does not induce typical side effects associated with hyperestrogenism (or hypoestrogenism) including hot flashes, bone loss, thrombophilia, hypercoagulation, or increased body fat. Unlike diethylstilbestrol, GTx-758 also does not induce gynecomastia in male monkeys, despite similarly suppressing testosterone levels to the castrate range (≤50 ng/dL) and markedly reducing PSA levels.
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Through collaboration with Javier de Mendoza in 1993, Rebek managed to create a self-assembling capsule. These form reversibly by completely surrounding small molecule targets and have become a versatile tool of modern physical organic chemistry. They exist in solution at equilibrium and under ambient conditions. They act as nanometric reaction chambers, as means to stabilize reagents, as sources of "complexes within complexes" and as spaces where new forms of stereochemistry have been created.
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Butantoxin reversibly blocks the voltage-gated K+ channels, Shaker B and Kv1.2, and the Ca2+-activated K+ channels, Kca1.1 and Kca3.1. Thus, butantoxin has the capacity to interact with a variety of K+ channels and has a variable affinity for each K+ channel. This suggests butantoxin has some conformational flexibility despite its 4 disulfide bonds. This flexibility would then allow its structure to fit into the pore region of this diverse range of K+ channels.
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Neuroglobin is a member of the vertebrate globin family involved in cellular oxygen homeostasis and reactive oxygen/nitrogen scavenging. It is an intracellular hemoprotein expressed in the central and peripheral nervous system, cerebrospinal fluid, retina and endocrine tissues. Neuroglobin is a monomer that reversibly binds oxygen with an affinity higher than that of hemoglobin. It also increases oxygen availability to brain tissue and provides protection under hypoxic or ischemic conditions, potentially limiting brain damage.
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Inspired by it, many functional superhydrophobic surfaces have been prepared. An example of a bionic or biomimetic superhydrophobic material in nanotechnology is nanopin film. One study presents a vanadium pentoxide surface that switches reversibly between superhydrophobicity and superhydrophilicity under the influence of UV radiation. According to the study, any surface can be modified to this effect by application of a suspension of rose-like V2O5 particles, for instance with an inkjet printer.
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The blockade of opioid receptors is the basis behind naltrexone's action in the management of opioid dependence--it reversibly blocks or attenuates the effects of opioids. Its mechanism of action in alcohol dependence is generated via κ-opioid receptor antagonism, which blocks the actions of the endogenous opioid peptide dynorphin. Dynorphin typically instates drug-seeking behavior when it binds to the κ-opioid receptor, as well as decreasing dopaminergic signalling in the nucleus accumbens.
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Fluomine is a chemical compound containing a cobalt chelate. It has the ability to form a complex with molecular oxygen (O2) and then release it upon heating. Because of this ability to reversibly sorb and desorb oxygen, it has been used in high-altitude aircraft oxygen-generating systems. The toxicity of fluomine has been studied and it is classified by the Emergency Planning and Community Right-to-Know Act as an extremely hazardous substance.
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Canadian Mineralogist 15, 30-35. KHP dissociates completely in water, giving the potassium cation (K+) and hydrogen phthalate anion (HP− or Hphthalate−). : KHP + H2O K+ \+ HP− And then as a weak acid hydrogen phthalate reacts reversibly with water to give hydronium (H3O+) and phthalate ions. : HP− \+ H2O P2− \+ H3O+ KHP can be used as a buffering agent in combination with hydrochloric acid (HCl) or sodium hydroxide (NaOH) depending on which side of pH 4.0 the buffer is to be.
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Donepezil binds and reversibly inactivates the cholinesterases, thus inhibiting hydrolysis of acetylcholine. This increases acetylcholine concentrations at cholinergic synapses. The precise mechanism of action of donepezil in patients with Alzheimer's disease is not fully understood. Certainly, Alzheimer's disease involves a substantial loss of the elements of the cholinergic system and it is generally accepted that the symptoms of Alzheimer's disease are related to this cholinergic deficit, particularly in the cerebral cortex and other areas of the brain.
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Pi4 binds to Shaker B potassium channels, the Drosophila homologue of the voltage-gated potassium channel Kv1.1. Pi4 reversibly blocks this channel with an IC50 of 3.0 ± 2.2 nM. A Pi4 peptide, synthesized with a different C-terminus than the natural Pi4 (COO- instead of COH2N), shows the same binding characteristics as natural Pi4. This suggests that the C-terminus of the peptide Pi4 is not involved in the binding of Pi4 to the Shaker B channel.
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Demecarium bromide, trade name Humorsol, is a carbamate parasympathomimetic drug that acts as an acetylcholinesterase inhibitor, and is used as a glaucoma medication. It is applied directly to the eye in order to reduce elevated intraocular pressure associated with glaucoma. Demecarium causes constriction of the pupil (miosis), which improves the drainage of the fluid in the eye (aqueous humour). As demecarium reversibly inhibits cholinesterase, it can be administered less frequently than other parasympathomimetic drugs, such as carbachol.
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Rb has the ability to reversibly inhibit DNA replication through transcriptional repression of DNA replication factors. Rb is able to bind to transcription factors in the E2F family and thereby inhibit their function. When Rb is chronically activated, it leads to the downregulation of the necessary DNA replication factors. Within 72–96 hours of active Rb induction in A2-4 cells, the target DNA replication factor proteins—MCMs, RPA34, DBF4, RFCp37, and RFCp140—all showed decreased levels.
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A coboglobin is a synthetic compound, a metalloprotein chemically similar to hemoglobin or myoglobin but using the metal cobalt instead of iron (hence the name). Just like hemoglobin and myoglobin, the coboglobins are able to reversibly bind molecular oxygen (O2) at the metal atom. However they lose this ability much faster than the natural molecules. Blood of this type would be uncoloured and clear when in the veins while amber yellow in colour in the arteries.
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In this case the mutant version will out compete for the wildtype proteins partners resulting in a mutant phenotype. Other mutant forms can result in a protein that is abnormally regulated and constitutively active ('on' all the time). This might be due to removing a regulatory domain or mutating a specific amino residue that is reversibly modified (by phosphorylation, methylation, or ubiquitination). Either change is critical for modulating protein function and often result in informative phenotypes.
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This improves oxygen delivery in the periphery and contributes to the control of respiration. NO binds reversibly to a specific cysteine residue in globin; the binding depends on the state (R or T) of the hemoglobin. The resulting S-nitrosylated hemoglobin influences various NO-related activities such as the control of vascular resistance, blood pressure and respiration. NO is not released in the cytoplasm of red blood cells but transported out of them by an anion exchanger called AE1.
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It is no longer clinically used for this indication in the USA as less toxic and more effective agents are available. The marketing authorization for nalidixic acid has been suspended throughout the EU. It is also a tool in studies as a regulation of bacterial division. It selectively and reversibly blocks DNA replication in susceptible bacteria. Nalidixic acid and related antibiotics inhibit a subunit of DNA gyrase and topoisomerase IV and induce formation of cleavage complexes.
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Yet, some studies show that physiologic concentration of hydrogen sulfide may not be strong enough to trigger such responses. Other theories suggest it may involve mitochondrial oxygen sensors and the haem-containing cytochromes that undergo reversible one-electron reduction during oxidative-phosphorylation. Haem reversibly binds O2 with an affinity similar to that of the carotid body, suggesting that haem containing proteins may have a role in O2, potentially this could be one of the complexes involved in oxidative-phosphorylation.
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This gene encodes a member of the gelsolin/villin family of actin-regulatory proteins. The encoded protein reversibly blocks the barbed ends of F-actin filaments in a Ca2+ and phosphoinositide-regulated manner, but does not sever preformed actin filaments. By capping the barbed ends of actin filaments, the encoded protein contributes to the control of actin-based motility in non- muscle cells. Alternatively spliced transcript variants have been observed, but have not been fully described.
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Between these spheres a certain amount of charge is reversibly exchanged. In the first step the energy WI of the transfer of a specific amount of charge is calculated, e.g. for the system in a state when both spheres carry half of the amount of charge which is to be transferred. This state of the system can be reached by transferring the respective charge from the donor sphere to the vacuum and then back to the acceptor sphere.
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Avibactam on the other hand does not contain a beta-lactam ring (non beta-lactam beta-lactamase inhibitor), and instead binds reversibly. Ambler Class B beta-lactamases cleave beta-lactams by a mechanism similar to that of metalloproteases. As no covalent intermediate is formed, the mechanism of action of marketed beta-lactamase inhibitors is not applicable. Thus the spread of bacterial strains expressing metallo beta-lactamases such as the New Delhi metallo-beta-lactamase 1 has engendered considerable concern.
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Estrone is biosynthesized from cholesterol. The principal pathway involves androstenedione as an intermediate, with androstenedione being transformed into estrone by the enzyme aromatase. This reaction occurs in both the gonads and in certain other tissues, particularly adipose tissue, and estrone is subsequently secreted from these tissues. In addition to aromatization of androstenedione, estrone is also formed reversibly from estradiol by the enzyme 17β-hydroxysteroid dehydrogenase (17β-HSD) in various tissues, including the liver, uterus, and mammary gland.
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Estrone is conjugated into estrogen conjugates such as estrone sulfate and estrone glucuronide by sulfotransferases and glucuronidases, and can also be hydroxylated by cytochrome P450 enzymes into catechol estrogens such as 2-hydroxyestrone and 4-hydroxyestrone or into estriol. Both of these transformations take place predominantly in the liver. Estrone can also be reversibly converted into estradiol by 17β-HSD. The blood half-life of estrone is about 10 to 70 minutes and is similar to that of estradiol.
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An animation of the structure of the dark state of dronpa protein Dronpa is a reversibly switchable photoactivatable fluorescent protein that is 2.5 times as bright as EGFP. Dronpa gets switched off by strong illumination with 488 nm (blue) light and this can be reversed by weak 405 nm UV light. A single dronpa molecule can be switched on and off over 100 times. It has an excitation peak at 503 nm and an emission peak at 518 nm.
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Enzyme immobilization in hydrogels is a fairly well-established process. Reversibly cross-linked polymer networks and hydrogels can be similarly applied to a biological system where the response and release of a drug is triggered by the target molecule itself. Alternatively, the response might be turned on or off by the product of an enzyme reaction. This is often done by incorporating an enzyme, receptor or antibody, that binds to the molecule of interest, into the hydrogel.
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Mycophenolate can be derived from the fungi Penicillium stoloniferum, P. brevicompactum and P. echinulatum. Mycophenolate mofetil is metabolised in the liver to the active moiety mycophenolic acid. It reversibly inhibits inosine monophosphate dehydrogenase, the enzyme that controls the rate of synthesis of guanine monophosphate in the de novo pathway of purine synthesis used in the proliferation of B and T lymphocytes. Other cells recover purines via a separate salvage pathway and are thus able to escape the effect.
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The most stable lithium titanate phase is β-Li2TiO3 that belongs to the monoclinic system. A high- temperature cubic phase exhibiting solid-solution type behavior is referred to as γ-Li2TiO3 and is known to form reversibly above temperatures in the range 1150-1250 °C. A metastable cubic phase, isostructural with γ-Li2TiO3 is referred to as α-Li2TiO3; it is formed at low temperatures, and transforms to the more stable β-phase at 400 °C.
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The elasticity is derived from the ability of the long chains to reconfigure themselves to distribute an applied stress. The covalent cross-linkages ensure that the elastomer will return to its original configuration when the stress is removed. As a result of this extreme flexibility, elastomers can reversibly extend from 5–700%, depending on the specific material. Without the cross- linkages or with short, uneasily reconfigured chains, the applied stress would result in a permanent deformation.
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The activated carbon may be saturated with copper, zinc, silver and molybdenum compounds, as well as with triethylenediamine (TEDA) Many chemicals cannot be safely filtered out by any chemical cartridge. Chemical cartridges must generally be kept sealed from the air until use, and will eventually be too old to use even if kept sealed. Many chemicals bond to the cartridge material fairly irreversibly, through chemisorption. But some adsorbed organic vapours may only bond weakly and reversibly (for example methanol).
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The blood cells are mainly red blood cells (also called RBCs or erythrocytes), white blood cells (also called WBCs or leukocytes) and platelets (also called thrombocytes). The most abundant cells in vertebrate blood are red blood cells. These contain hemoglobin, an iron-containing protein, which facilitates oxygen transport by reversibly binding to this respiratory gas and greatly increasing its solubility in blood. In contrast, carbon dioxide is mostly transported extracellularly as bicarbonate ion transported in plasma.
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The reaction depicted below describes the hydrogenation of benzophenone: :Base-catalyzed hydrogenation of ketones. A chemical kinetics study found this reaction is first-order in all three reactants suggesting a cyclic 6-membered transition state. Another system for metal-free hydrogenation is based on the phosphine- borane, compound 1, which has been called a frustrated Lewis pair. It reversibly accepts dihydrogen at relatively low temperatures to form the phosphonium borate 2 which can reduce simple hindered imines.
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The function of vanadocytes is still unclear. It has been proposed that the vanadocyte transports and processes nutrients, contributes to the polysaccharide external tunic, or serves as a defense mechanism. It is unlikely that the vanadium complex serves as an oxygen transport mechanism because it is unable to reversibly bind oxygen. Research into their utility as anti-biofouling (allelopathic) mechanisms concluded that the high acidity and high vanadium levels function to significantly reduce epizoic recruitment and predation.
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He saw the possibility of binding two materials reversibly in a simple fashion, if he could figure out how to duplicate the hooks and loops. Initially people refused to take him and his idea seriously. He took his idea to Lyon, which was then a centre of weaving, where he did manage to gain the help of one weaver, who made two cotton strips that worked. However, the cotton wore out quickly, so de Mestral turned to synthetic fibres.
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Levamisole reversibly and noncompetitively inhibits most isoforms of alkaline phosphatase (e.g., human liver, bone, kidney, and spleen) except the intestinal and placental isoform. It is thus used as an inhibitor along with substrate to reduce background alkaline phosphatase activity in biomedical assays involving detection signal amplification by intestinal alkaline phosphatase, for example in in situ hybridization or Western blot protocols. It is used to immobilize the nematode C. elegans on glass slides for imaging and dissection.
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Opicapone blocks the enzyme catechol-O-methyltransferase (COMT) effectively (>90% at therapeutic doses), selectively and reversibly, and only outside the central nervous system. It dissociates slowly from COMT, resulting in a duration of action longer than 24 hours despite its short blood plasma half-life. As COMT and DOPA decarboxylase are the main enzymes for degrading levodopa, blocking the two effectively increases its concentrations in the bloodstream. More levodopa reaches the brain, where it is activated to dopamine.
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Afobazole from Russia Fabomotizole (INN; brand name Afobazole) is an anxiolytic drug launched in Russia in the early 2000s. It produces anxiolytic and neuroprotective effects without any sedative or muscle relaxant actions. Its mechanism of action remains poorly defined however, with GABAergic, NGF- and BDNF-release-promoting, MT1 receptor agonism, MT3 receptor antagonism, and sigma agonism suggested as potential mechanisms. Fabomotizole was shown to inhibit MAO-A reversibly and there might be also some involvement with serotonin receptors.
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EGFR is an oncogenic driver and patients with somatic mutations, particularly an exon 19 deletion or exon 21 L858R mutation, within the tyrosine kinase domain have activating mutations that lead to unchecked cell proliferation. Overexpression of EGFR causes inappropriate activation of the anti-apoptotic Ras signaling pathway, found in many different types of cancer. Icotinib is a quinazoline derivative that binds reversibly to the ATP binding site of the EGFR protein, preventing completion of the signal transduction cascade.
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Like other globins, penta-coordinate Phytogbs reversibly bind and transport O2. The function of Lbs in nodules was elucidated in 1974 by Wittenberg, Appleby and others.Wittenberg J. B., Bergersen F. J., Appleby C. A.,Turner G. L., Facilitated oxygen diffusion: the role of leghemoglobin in nitrogen fixation by bacteroids isolated from soybean root nodules., J. Biol. Chem., 249 (1974) 4057-4066 In nodules the concentration of Lbs is very high as they correspond to ~30% of the total soluble proteins.
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In this algorithmic process entropy is transferred reversibly to specific qubits (named reset spins) that are coupled with the environment much more strongly than others. After a sequence of reversible steps that let the entropy of these reset qubits increase they become hotter than the environment. Then the strong coupling results in a heat transfer (irreversibly) from these reset spins to the environment. The entire process may be repeated and may be applied recursively to reach low temperatures for some qubits.
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In May 2013 he joined the Institute for Systems Biology, in Seattle, Washington. Following the death of his wife, Kauffman cofounded Transforming Medicine: The Elizabeth Kauffman Institute. In 2014, Kauffman with Samuli Niiranen and Gabor Vattay was issued a founding patent on the poised realm (see below), an apparently new "state of matter" hovering reversibly between quantum and classical realms. In 2015, he was invited to help initiate a general a discussion on rethinking economic growth for the United Nations.
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Schiff bases have been investigated in relation to a wide range of contexts, including antimicrobial, antiviral and anticancer activity. They have also been considered for the inhibition of amyloid-β aggregation. Schiff bases are common enzymatic intermediates where an amine, such as the terminal group of a lysine residue, reversibly reacts with an aldehyde or ketone of a cofactor or substrate. The common enzyme cofactor PLP forms a Schiff base with a lysine residue and is transaldiminated to the substrate(s).
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Sodium–air batteries were proposed with the hopes of overcoming the battery instability associated with superoxide in lithium–air batteries. Sodium, with an energy density of 1605 Wh/kg, does not boast as high an energy density as lithium. However, it can form a stable superoxide (NaO) as opposed to the superoxide undergoing detrimental secondary reactions. Since NaO will decompose reversibly to an extent back to the elemental components, this means sodium–air batteries have some intrinsic capacity to be rechargeable.
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Phosphites add reversibly to the carbonyl carbon of simple carbonyl compounds. Under mild conditions, reversion to the starting materials is faster than both inter- and intramolecular alkyl group transfer—the four-center transition state for intramolecular transfer exhibits poor orbital overlap. Transfer can be facilitated under conditions of high temperature or pressure. If two equivalents of aldehyde are used, addition of the tetrahedral intermediate to a second molecule of aldehyde leads either to cyclic phosphoranes 1 or linear alkyl transfer products 2.
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At one time, stable carbenes were thought to reversibly dimerise through the so-called Wanzlick equilibrium. However, imidazol-2-ylidenes and triazol-5-ylidenes are thermodynamically stable and do not dimerise, and have been stored in solution in the absence of water and air for years. This is presumably due to the aromatic nature of these carbenes, which is lost upon dimerisation. In fact imidazol-2-ylidenes are so thermodynamically stable that only in highly constrained conditions are these carbenes forced to dimerise.
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Reversible hydrogen storage is exhibited by frustrated Lewis pair, which produces a borohydride.Elizabeth Wilson H2 Activation, Reversibly Metal-free compound readily breaks and makes hydrogen, Chemical & Engineering News November 20, 2006Mes stands for a mesityl substituent and C6F5 for a pentafluorophenyl group, see also tris(pentafluorophenyl)boron Phosphino borane hydrogenstorage The phosphino-borane on the left accepts one equivalent of hydrogen at one atmosphere and 25 °C and expels it again by heating to 100 °C. The storage capacity is 0.25 wt%.
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Selective enzyme and antibody separation can be achieved with the use of specific end groups that conjugate with the specific compounds. This results in a formation of a polymer-enzyme conjugate which can be reversibly precipitated and dissolved by changing the temperature. Chen and Hoffman used N-Hydroxysuccinimide (NHS) ester functional end group on NIPAAm to conjugate selectively with β-D-glucosidase. They found that the conjugated enzyme could be repeatedly precipitated and dissolved in solution and still maintain sufficient enzymatic activity.
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Reduction of Ru(acac)3 in the presence of alkenes affords the related diolefin complexes. Typically, such reactions are conducted with zinc amalgam in moist tetrahydrofuran: :2 Ru(acac)3 \+ 4 alkene + Zn → 2 Ru(acac)2(alkene)2 \+ Zn(acac)2 The resulting compounds are rare examples of metal-alkene complexes that reversibly sustain oxidation: :Ru(acac)2(alkene)2 [Ru(acac)2(alkene)2]+ \+ e− The complex has been resolved into individual enantiomers by separation of its adduct with dibenzoyltartaric acid.
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Drugs that are substrates for the UDP-glucuronosyltransferase (UGT) enzymes which metabolize 20-HETE such as non-steroidal anti-inflammatory agents, opioids, gemfibrozil, Lasix, propanol, and various COX-2 inhibitors may act as perhaps unwanted side effects to increase the levels of 20-HETE. There are a variety of pharmacological agents which inhibit the synthesis of 20-HETE including various fatty acid analogs that compete reversibly with arachidonic acid for the substrate binding site in the CYP enzymes and benzene-based drugs.
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Small molecular direct thrombin inhibitors (smDTIs) are non-peptide small molecules that specifically and reversibly inhibit both free and clot-bound thrombin by binding to the active site of the thrombin molecule. They prevent VTE in patients undergoing hip- and knee replacement surgery. The advantages of this type of DTIs are that they do not need monitoring, have a wide therapeutic index and the possibility of oral administration route. They are theoretically more convenient than both vitamin K antagonist and LMWH.
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This sulfhydryl can also be reversibly inhibited by NO in an elegant form of negative feedback. Homocysteine (a putative cardiovascular risk factor) mounts an oxidative attack on DDAH to form a mixed disulfide, inactivating the enzyme. By oxidizing a sulfhydryl moiety critical for DDAH activity, homocysteine and other risk factors cause ADMA to accumulate and to suppress nitric oxide synthase (NOS) activity. The critical role of DDAH activity in regulating NO synthesis in vivo was demonstrated using a transgenic DDAH mouse.
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Spheres of nickel made by the Mond process The Mond process, sometimes known as the carbonyl process, is a technique created by Ludwig Mond in 1890, to extract and purify nickel. The process was used commercially before the end of the 19th century. This process converts nickel oxides into nickel metal with very high purity being attainable in just a single process. This process involves the fact that carbon monoxide combines with nickel readily and reversibly to give nickel carbonyl.
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An experimental demonstration may be considered. The two distinct gases, in a cylinder of constant total volume, are at first separated by two contiguous pistons made respectively of two suitably specific ideal semipermeable membranes. Ideally slowly and fictively reversibly, at constant temperature, the gases are allowed to mix in the volume between the separating membranes, forcing them apart, thereby supplying work to an external system. The energy for the work comes from the heat reservoir that keeps the temperature constant.
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Some cells use higher-capacity negative electrode materials based on AB2 compounds, where A is titanium or vanadium, and B is zirconium or nickel, modified with chromium, cobalt, iron, or manganese. Any of these compounds serve the same role, reversibly forming a mixture of metal hydride compounds. When overcharged at low rates, oxygen produced at the positive electrode passes through the separator and recombines at the surface of the negative. Hydrogen evolution is suppressed, and the charging energy is converted to heat.
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Some rare organisms, such as tardigrades, usually have short lifespans, but are able to survive for thousands of years—and, perhaps, indefinitely—if they enter into the state of cryptobiosis, whereby their metabolism is reversibly suspended. It is hypothesized by advocates of cryonics that the human central nervous system can be similarly put into a state of suspended animation shortly before brain death to be revived at a future point in the technological development of humankind when such operation would be possible.
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Vaska's complex is the trivial name for the chemical compound trans- carbonylchlorobis(triphenylphosphine)iridium(I), which has the formula IrCl(CO)[P(C6H5)3]2. This square planar diamagnetic organometallic complex consists of a central iridium atom bound to two mutually trans triphenylphosphine ligands, carbon monoxide and a chloride ion. The complex was first reported by J. W. DiLuzio and Lauri Vaska in 1961. Vaska's complex can undergo oxidative addition and is notable for its ability to bind to O2 reversibly.
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The rate of the Grubbs catalyst can be altered by replacing the phosphine ligand with more labile pyridine ligands. By using 3-bromopyridine the initiation rate is increased more than a millionfold. Both pyridine and 3-bromopyridine are commonly used, with the bromo- version 4.8 times more labile resulting in even faster rates. The catalyst is traditionally isolated as a two pyridine complex, however one pyridine is lost upon dissolving and reversibly inhibits the ruthenium center throughout any chemical reaction.
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The anodes of lithium-ion batteries are often made of oxides of cobalt, nickel, or iron, that can readily and reversibly incorporate lithium ions in their molecular structure. Cobalt oxide nanoparticles, such as nanotubes, offer high surface-to-volume ratio and short path length for lithium cation transport, leading to high reversible capacity and good cycle life. The particles may incorporate other substances, asfor example diphenylalanine/cobalt oxide hybrid nanowires. Cobalt oxide (Co3O4) nanoparticles anchored on a single sheet of graphene.
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Phorbol derivatives work primarily by interacting with protein kinase C (PKC), although they can interact with other phospholipid membrane receptors. The esters bind to PKC in a similar way to its natural ligand, diacylglycerol, and activate the kinase. Diacylglycerol is degraded quickly by the body, allowing PKC to be reversibly activated. When phorbol esters bind to the receptor, they are not degraded as efficiently by the body, leading to constitutively active PK. PKC is involved in a number of important cell signaling pathways.
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The iron ion, which is the site of oxygen binding, coordinates with the four nitrogen atoms in the center of the ring, which all lie in one plane. The iron is bound strongly (covalently) to the globular protein via the N atoms of the imidazole ring of F8 histidine residue (also known as the proximal histidine) below the porphyrin ring. A sixth position can reversibly bind oxygen by a coordinate covalent bond,WikiPremed > Coordination Chemistry . Retrieved July 2, 2009 completing the octahedral group of six ligands.
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All LAs are membrane-stabilizing drugs; they reversibly decrease the rate of depolarization and repolarization of excitable membranes (like nociceptors). Though many other drugs also have membrane-stabilizing properties, not all are used as LAs (propranolol, for example, though it has LA properties). LA drugs act mainly by inhibiting sodium influx through sodium-specific ion channels in the neuronal cell membrane, in particular the so-called voltage-gated sodium channels. When the influx of sodium is interrupted, an action potential cannot arise and signal conduction is inhibited.
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This makes the inhibition of the cholinesterase permanent. The cholinesterase gets irreversible phosphorylated according to the following reaction scheme E + PX <=> E-PX ->[k_3] EP + X In this reaction scheme the E indicates the cholinesterase, PX the TEPP molecule, E–PX the reversible phosphorylated cholinesterase, k3 the reaction rate of the second step, EP the phosphorylated cholinesterase and X the leaving group of the TEPP. The irreversible phosphorylation of the cholinesterase occurs in two steps. In the first step the cholinesterase gets reversibly phosphorylated.
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Further extrapolation of the CTO and CBR models are DEBtox, which can model sublethal endpoints, and hazard versions of the CTO, which takes into account stochastic death as opposed to individual tolerance.Jager et al. 2011 Another significant step to developing TKTD models was the incorporation of a state variable for damage. By using damage as a toxicodynamic state-variable, modeling intermediate recovery rates can be accomplished for toxicants that act reversibly with their targets, without the assumptions of instant recovery (CBR model) or irreversible interactions (CTO model).
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Biophysical analyses and mathematical modelling has shown that MIP-1 reversibly forms a polydisperse distribution of rod-shaped polymers in solution. Polymerization buries receptor-binding sites of MIP-1, thus depolymerization mutations enhance MIP-1 to arrest monocytes onto activated human endothelium. MIP-1γ is another macrophage inflammatory protein and according to the new nomenclature is named CCL9. It is produced mainly by follicle-associated epithelial cells and is responsible for chemotaxis of dendritic cells and macrophages into Peyer's patches in gut through binding of CCR1.
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PDB3CEH, PDB3E3O In mammals, the major isozymes of glycogen phosphorylase are found in muscle, liver, and brain. The brain type is predominant in adult brain and embryonic tissues, whereas the liver and muscle types are predominant in adult liver and skeletal muscle, respectively. The glycogen phosphorylase dimer has many regions of biological significance, including catalytic sites, glycogen binding sites, allosteric sites, and a reversibly phosphorylated serine residue. First, the catalytic sites are relatively buried, 15Å from the surface of the protein and from the subunit interface.
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The engine takes in a quantity of heat from a hot reservoir and passes out a lesser quantity of heat to a cold reservoir. The difference in energy is passed, as thermodynamic work, to a work reservoir, and is considered to be the output of the engine. The cycle is imagined to run so slowly that at each point of the cycle the working body is in a state of thermodynamic equilibrium. The successive processes the cycle are thus imagined to run reversibly with no entropy production.
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In a series of now classic studies Schiller characterized the functions of two sets of parallel pathways in the visual system: The On- and Off- pathways and the midget and parasol pathways. By administering 2-amino-4-phosphono-butyrate (APB) to the eye, he was able to inactivate the ON-retinal pathway reversibly and demonstrate that the On- and Off-pathways remain segregated from the retina to the striate cortex.P.H. Schiller, Central connections of the retinal ON and OFF pathways. (1982) Nature, 297, 580-583.
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Silanes are generally used on nonmetallic oxide surfaces; however monolayers formed from covalent bonds between silicon and carbon or oxygen cannot be considered self assembled because they do not form reversibly. Self-assembled monolayers of thiolates on noble metals are a special case because the metal- metal bonds become reversible after the formation of the thiolate-metal complex. This reversibility is what gives rise to vacancy islands and it is why SAMs of alkanethiolates can be thermally desorbed and undergo exchange with free thiols.
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It is still used in modern times to reversibly assemble joints; after it has dried, the glue can be soaked, steamed, or split to re-open the joint; on a small wood joint, the glue is resistant to tens of minutes of water immersion. It is sometimes mixed 1:1 with urushi lacquer to make nori- urushi (Japanese term), which is darker and dries faster than undiluted lacquer, and is used in making lacquerware. Rice glue is frequently used in Japan and in China.
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V-ATPases are known to be specifically inhibited by macrolide antibiotics, such as concanamycin (CCA) and balifomycin A1. In vivo regulation of V-ATPase activity is accomplished by reversible dissociation of the V1 domain from the Vo domain. After initial assembly, both the insect Manduca sexta and yeast V-ATPases can reversibly disassemble into free Vo and V1 domains after a 2- to 5-minute deprivation of glucose. Reversible disassembly may be a general mechanism of regulating V-ATPase activity, since it exists in yeast and insects.
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Thiomers are able to reversibly inhıbit efflux pumps. Because of this property the mucosal uptake of various efflux pump substrates such as anticancer drugs, antimycotic drugs and antiinflammatory drugs can be tremendously ımproved. The postulated mechanism of efflux pump inhibition is based on an interaction of thiolated polymers with the channel forming transmembrane domain of various efflux pumps such as P-gp and multidrug resistance proteins (MRPs). P-gp, for instance, exhibits 12 transmembrane regions forming a channel through which substrates are transported outside of the cell.
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He took a close look at the burs of burdock that kept sticking to his clothes and his dog's fur. He examined them under a microscope, and noted their hundreds of "hooks" that caught on anything with a loop, such as clothing, animal fur, or hair. He saw the possibility of binding two materials reversibly in a simple fashion if he could figure out how to duplicate the hooks and loops. Hook-and-loop is viewed by some like Steven Vogel or Werner NachtigallNachtigall, W. 1974.
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This assertion was validated by Rudolf Schoenheimer's work with radioisotopes as tracers in 1937. This in turn would pave the way for the possibility that similar transfers were a primary means of producing most amino acids via amino transfer. Another such example of early transferase research and later reclassification involved the discovery of uridyl transferase. In 1953, the enzyme UDP-glucose pyrophosphorylase was shown to be a transferase, when it was found that it could reversibly produce UTP and G1P from UDP-glucose and an organic pyrophosphate.
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Phencyclidine is an NMDA receptor antagonist that blocks the activity of the NMDA receptor to cause anaesthesia and analgesia without causing cardiorespiratory depression. NMDA is an excitatory receptor in the brain, when activated normally the receptor acts as an ion channel and there is an influx of positive ions through the channel to cause nerve cell depolarisation. Phencyclidine enters the ion channel and binds, reversibly and non-competitively, inside the channel pore to block the entry of positive ions to the cell, thereby inhibiting cell depolarisation.
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Cerimetry or cerimetric titration, also known as cerate oximetry, is a method of volumetric chemical analysis developed by Ion Atanasiu. It is a redox titration in which a Fe2+-1,10-phenanthroline complex (ferroin) color change indicates the end point. Ferroin can be reversibly discolored in its oxidized form upon titration with a Ce4+ solution. The use of cerium(IV) salts as reagents for volumetric analysis was first proposed in the middle of 19th century, but systematic studies did not start until about 70 years later.
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MSP dimers are the smallest building blocks for these assemblies, none of which have overall polarity: #subfilaments, formed from dimers, connected to a long helix. The dimer-dimer interface within the single subfilament is formed by residues 112-119 of two A. suum MSP chains, which produce an anti-parallel β-strand-β-strand pairing. The interaction is less hydrophobic and results mostly from formation of hydrogen bonds, typically for interfaces between reversibly interacting molecules. # filaments, formed by two subfilaments coiling round one another.
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At therapeutic concentrations, ixazomib selectively and reversibly inhibits the protein proteasome subunit beta type-5 (PSMB5) with a dissociation half-life of 18 minutes. This mechanism is the same as of bortezomib, which has a much longer dissociation half-life of 110 minutes; the related drug carfilzomib, by contrast, blocks PSMB5 irreversibly. Proteasome subunits beta type-1 and type-2 are only inhibited at high concentrations reached in cell culture models. PSMB5 is part of the 20S proteasome complex and has enzymatic activity similar to chymotrypsin.
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Additional methanol and ethanol monolayer is reversibly inserted into the structure of Brodie graphite oxide also at high pressure conditions. Hummers graphite oxide is intercalated with two methanol or ethanol monolayers already at ambient temperature. The interlayer distance of Hummers graphite oxide in excess of liquid alcohols increases gradually upon temperature decrease, reaching 19.4 and 20.6 Å at 140 K for methanol and ethanol, respectively. The gradual expansion of the Hummers graphite oxide lattice upon cooling corresponds to insertion of at least two additional solvent monolayers.
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Ionophores are chemical compounds that reversibly bind and transport ions through biological membranes in the absence of a protein pore. This can disrupt the membrane potential, and thus these substances could exhibit cytotoxic properties. Ionophores modify the permeability of biological membranes toward certain ions to which they show affinity and selectivity. Many ionophores are lipid-soluble and transport ions across hydrophobic membranes, such as lipid bilayers found in the living cells or synthetic vesicles (liposomes), or liquid polymeric membranes (carrier-based ion selective electrodes).
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IBA has developed an affinity chromatography system for non-magnetic isolation of peripheral blood mononuclear cells, T cells, B cells and other cells of interest. This technology is known as Fab-TACS (Traceless Affinity Cell Selection) and is based on Strep-tagged Fab fragments, which reversibly capture and release the target cells. This delivers label-free, non-activated cells suitable for immunologic or cell biological assays. The technology can be used with manual gravity flow columns as well as with the automated cell selection device FABian.
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SPS- kinase reversibly phosphorylates a serine residue and subsequently deactivates SPS, In spinach and maize, the site of phosphorylation regulation has been identified as Ser158 and Ser162 respectively. While it is currently unclear if this seryl residue homolog in other plant SPSes is phosphorylated to suppress SPS activity, conservation of the neighboring residues has been observed in other plant species. This conserved sequence may potentially aid in recognition of a regulatory SPS-kinase. Once phosphorylated, the inactivated enzyme can be dephosphorylated and reactivated by SPS-phosphatase.
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Harmine, also known as banisterine and as telepathine, a fluorescent harmala alkaloid belonging to the beta-carboline family of compounds. It occurs in a number of different plants, most notably the Middle Eastern plant harmal or Syrian rue (Peganum harmala) and the South American vine Banisteriopsis caapi (also known as "yage" or "ayahuasca"). Harmine reversibly inhibits monoamine oxidase A (MAO-A), an enzyme which breaks down monoamines, making it a RIMA. Harmine selectively binds to MAO-A but does not inhibit the variant MAO-B.
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Electron doping is achieved by extracting O2− ions from the C12A7 structure via chemical reduction. The injected electrons occupy a unique conduction band called 'the cage conduction band', and migrate through the C12A7:e− crystal by tunneling. They can be readily and reversibly replaced with hydride ions (H−) by heating C12A7:e− in a hydrogen atmosphere. Owing to this reversibility, C12A7:e− does not suffer from hydrogen poisoning – irreversible deterioration of properties upon exposure to hydrogen which is common to traditional catalysts used in the ammonia synthesis.
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These cleavages are carried out by two distinct proteases, called site-1 protease (S1P) and site-2 protease (S2P). In addition to S1P and S2P, the regulated release of transcriptionally active SREBP requires the cholesterol-sensing protein SREBP cleavage-activating protein (SCAP), which forms a complex with SREBP owing to interaction between their respective carboxy-terminal domains. SCAP, in turn, can bind reversibly with another ER-resident membrane protein, INSIG. In the presence of sterols, which bind to INSIG and SCAP, INSIG and SCAP also bind one another.
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Further heating to about 500 °C will reversibly remove the hydrogen. This property makes uranium hydrides convenient starting materials to create reactive uranium powder along with various uranium carbide, nitride, and halide compounds. The reversible reaction proceeds as follows: :2 U + 3 H2 2 UH3 Uranium hydride is not an interstitial compound, causing the metal to expand upon hydride formation. In its lattice, each uranium atom is surrounded by 6 other uranium atoms and 12 atoms of hydrogen; each hydrogen atom occupies a large tetrahedral hole in the lattice.
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Philanthotoxins reversibly inhibit AMPA (also called the "quisqualate receptor"), kainate, and NMDA ionotropic glutamate receptors (iGluRs).. Philanthotoxins have a hydrophobic aromatic head group and a hydrophilic polyamine tail, which allow them to inhibit iGluRs by binding within the ion channel. The nitrogen atoms of the polyamine tail have been proposed to interact with the negatively-charged or polar amino acids within the cation- selective channel pore. The aromatic head group anchors the molecule to the extracellular entrance to the channel. Inhibition may also occur via binding to an external allosteric polyamine binding site.
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Reversible activation/deactivation of peptide function are achieved by incorporation photo-controllable fragments (molecular photoswitches) in the side chains or in the backbone of peptide templates to get the photo- controlled peptides, which can reversibly change their structure upon irradiation with light of different wavelength. As the consequence, the properties, function and biological activity of the modified peptides can be controlled by light. Since light can be directed to specific areas, such peptides can be activated only at targeted sites. Azobenzenes, and diarylethenes can be used as the photoswitches.
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At humanity's present level of scientific knowledge, only cells, tissues, and some small organs can be reversibly cryopreserved. Large vitrified organs tend to develop fractures during cooling, a problem worsened by the large tissue masses and very low temperatures of cryonics. Actual cryonics organizations use vitrification without a chemical fixation step, sacrificing some structural preservation quality for less damage at the molecular level. Some scientists, like Joao Pedro Magalhaes, have questioned whether using a deadly chemical for fixation eliminates the possibility of biological revival, making chemical fixation unsuitable for cryonics.
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The membrane was exposed to cycles of high and low pH. Protons transferred reversibly from the aqueous phase through the graphene to the other side where they undergo acid–base chemistry with silica hydroxyl groups. Computer simulations indicated energy barriers of 0.61–0.75 eV for hydroxyl-terminated atomic defects that participate in a Grotthuss-type relay, while pyrylium-like ether terminations did not. Recently, Paul and co-workers at IISER Bhopal demonstrated solid state proton conduction for oxygen functionalized few-layer graphene (8.7x10−3 S/cm) with a low activation barrier (0.25 eV).
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The figure was created based on information provided for CK1δ by PhosphoSitePlus. Posttranslational modifications, especially site-specific phosphorylation mediated either by upstream kinases or by intramolecular autophosphorylation, have been demonstrated to reversibly modulate CK1δ kinase activity. Several residues within the C-terminal regulatory domain of CK1δ were identified as targets for autophosphorylation, including Ser-318, Thr-323, Ser-328, Thr-329, Ser-331, and Thr-337. Upon autophosphorylation sequence motifs within the C-terminal domain are generated, which are able to block the catalytic center of the kinase by acting as a pseudosubstrate.
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The protein encoded by this gene, CK-BB, consists of a homodimer of two identical brain-type CK-B subunits. BB-CK is a cytoplasmic enzyme involved in cellular energy homeostasis, with certain fractions of the enzyme being bound to cell membranes, ATPases, and a variety of ATP-requiring enzymes in the cell. There, CK-BB forms tightly coupled microcompartments for in situ regeneration of ATP that has been used up. The encoded protein reversibly catalyzes the transfer of "energy-rich" phosphate between ATP and creatine or between phospho- creatine (PCr) and ADP.
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John Varley, who also came to prominence in the 1970s, also often writes on gender-related themes. In his "Eight Worlds" suite of stories (many collected in The John Varley Reader) and novels, for example, humanity has achieved the ability to change sex at a whim. Homophobia is shown to initially inhibit uptake of this technology, as it engenders drastic changes in relationships, with homosexual sex becoming an acceptable option for all. In the Culture series of novels and stories by Iain M. Banks, humans can and do relatively easily (and reversibly) change sex.
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It has been argued that the current challenges facing risk assessments can be addressed with TKTD modeling. TKTD models were derived in response to a couple of factors. One is the lack of time being considered as a factor in toxicity and risk assessment. Some of the earliest developed TKTD models, such as the Critical Body Residue (CBR) model and Critical Target Occupation (CTO) model, have considered time as a factor but a criticism has been that they are for very specific circumstances such as reversibly acting toxicants or irreversibly acting toxicants.
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Another way to view the surface energy is to relate it to the work required to cut a bulk sample, creating two surfaces. There is "excess energy" as a result of the now-incomplete, unrealized bonding at the two surfaces. Cutting a solid body into pieces disrupts its bonds and increases the surface area, and therefore increases surface energy. If the cutting is done reversibly, then conservation of energy means that the energy consumed by the cutting process will be equal to the energy inherent in the two new surfaces created.
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Signal amplification by reversible exchange (SABRE) is a technique to hyperpolarize samples without chemically modifying them. Compared to orthohydrogen or organic molecules, a much greater fraction of the hydrogen nuclei in parahydrogen align with an applied magnetic field. In SABRE, a metal center reversibly binds to both the test molecule and a parahydrogen molecule facilitating the target molecule to pick up the polarization of the parahydrogen. This technique can be improved and utilized for a wide range of organic molecules by using an intermediate "relay" molecule like ammonia.
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In the case of non- volatile target analytes, the presence of the keeper solvent or solid is intended to prevent all the solvent from being evaporated off, thereby preventing the loss of analytes which might irreversibly adsorb to the container walls when completely dried, or if it is totally dried (in the case of a solid keeper), provide a surface where the analyte can be reversibly rather than irreversibly adsorbed A solid keeper of sodium sulfate was effective for reducing losses of polycyclic aromatic hydrocarbons (PAHs) in an evaporative procedure.
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A slightly milder set of conditions uses cyclohexyl iodide (CyI, 10.0 equiv) in N,N-dimethylformamide to generate a small amount of hydrogen iodide in situ. Boron tribromide, which can be used at room temperature or below, is a more specialized reagent for the demethylation of aryl methyl ethers. The mechanism of ether dealkylation proceeds via the initial reversible formation of a Lewis acid-base adduct between the strongly Lewis acidic BBr3 and the Lewis basic ether. This Lewis adduct can reversibly dissociate to give a dibromoboryl oxonium cation and Br–.
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Ribose 5-phosphate (R5P) is both a product and an intermediate of the pentose phosphate pathway. The last step of the oxidative reactions in the pentose phosphate pathway is the production of ribulose 5-phosphate. Depending on the body's state, ribulose 5-phosphate can reversibly isomerize to ribose 5-phosphate. Ribulose 5-phosphate can alternatively undergo a series of isomerizations as well as transaldolations and transketolations that result in the production of other pentose phosphates as well as fructose 6-phosphate and glyceraldehyde 3-phosphate (both intermediates in glycolysis).
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Dynamics of highly elastic mechanisms using the generalized multiple shooting method: Simulations and experiments. Mechanism and Machine Theory. Pg.2165-2178 When a force is applied to a spring it bends and stores energy in the form of elastic strain energy and when it recoils after the force has been released, this energy is released as well. Elastic proteins provide the property of elasticity which gives the spring the ability to bend reversibly without the loss of energy, and the ability to bend to large strains with small force.
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Thermochromic paints use liquid crystals or leuco dye technology. After absorbing a certain amount of light or heat, the crystallic or molecular structure of the pigment reversibly changes in such a way that it absorbs and emits light at a different wavelength than at lower temperatures. Thermochromic paints are seen quite often as a coating on coffee mugs, whereby once hot coffee is poured into the mugs, the thermochromic paint absorbs the heat and becomes colored or transparent, therefore changing the appearance of the mug. These are known as magic mugs or heat changing mugs.
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The reagent competes with the carbonyl for the reactive intermediate, rapidly sequestering [CF3]− in a reversibly-generated -ate complex [(CF3)2Si(CH3)3]−. This -ate complex is unable to react directly with the carbonyl, resulting in powerful inhibition of the chain reaction by the reagent. This inhibitory process is common to all anion-initiated reactions of the reagent, with the identity of the counter- cation (M+) playing a major role in controlling the overall rate. The reagent has largely supplanted trifluoromethyllithium, which is not isolable and rapidly decomposes to yield lithium fluoride and difluorocarbene.
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Aspartate aminotransferase can act on several different amino acids The grouping consistent with transfer of nitrogenous groups is EC 2.6. This includes enzymes like transaminase (also known as "aminotransferase"), and a very small number of oximinotransferases and other nitrogen group transferring enzymes. EC 2.6 previously included amidinotransferase but it has since been reclassified as a subcategory of EC 2.1 (single-carbon transferring enzymes). In the case of aspartate transaminase, which can act on tyrosine, phenylalanine, and tryptophan, it reversibly transfers an amino group from one molecule to the other.
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Flagellated bacteria swim towards favourable chemicals and away from deleterious ones. Sensing of chemoeffector gradients involves chemotaxis receptors, transmembrane (TM) proteins that detect stimuli through their periplasmic domains and transduce the signals via their cytoplasmic domains . Signalling outputs from these receptors are influenced both by the binding of the chemoeffector ligand to their periplasmic domains and by methylation of specific glutamate residues on their cytoplasmic domains. Methylation is catalysed by CheR, an S-adenosylmethionine-dependent methyltransferase, which reversibly methylates specific glutamate residues within a coiled coil region, to form gamma- glutamyl methyl ester residues.
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In the field of chemical biology, a chemical probe is a small molecule that is used to study and manipulate a biological system such as a cell or an organism by reversibly binding to and altering the function of a biological target (most commonly a protein) within that system. Probes ideally have a high affinity and binding selectivity for one protein target as well as high efficacy. By changing the phenotype of the cell, a molecular probe can be used to determine the function of the protein with which it interacts.
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In other countries, it is still used in homes, industrial plants, and food storage sites to control bedbugs, mosquitoes, flies, wasps, ants, fleas, cockroaches, silverfish, and ticks but can be used against a wide variety of insects as well as snails and slugs. It is one of 12 insecticides recommended by the World Health Organization for use in malaria control. Bendiocarb is not considered to be carcinogenic, but it is acutely toxic. Like other carbamates, it reversibly inhibits acetylcholinesterase, an enzyme required for normal transmission of nerve impulses.
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Etomidate suppresses corticosteroid synthesis in the adrenal cortex by reversibly inhibiting 11β-hydroxylase, an enzyme important in adrenal steroid production; it leads to primary adrenal suppression. Using a continuous etomidate infusion for sedation of critically ill trauma patients in intensive care units has been associated with increased mortality due to adrenal suppression. Continuous intravenous administration of etomidate leads to adrenocortical dysfunction. The mortality of patients exposed to a continuous infusion of etomidate for more than 5 days increased from 25% to 44%, mainly due to infectious causes such as pneumonia.
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The station has two platforms (linked by footbridge), with the ticket office and waiting room on platform 1 (both platforms are reversibly signalled).Forres station to ‘transform’ Scottish rail travel Railway Gazette; Retrieved 30 October 2017 The main road that used to cross the line at Forres East level crossing has been diverted onto a new overbridge and a new larger car park provided. A shelter is located on platform 2, whilst both have customer help points, CIS displays, timetable boards and automated announcements to offer train running details.
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Major changes are sometimes induced when the tyrosine kinase enzyme is affected by other factors. One of the factors is a molecule that is bound reversibly by a protein, called a ligand. A number of receptor tyrosine kinases, though certainly not all, do not perform protein- kinase activity until they are occupied, or activated, by one of these ligands. Although more research indicates that receptors remain active within endosomes, it was once thought that endocytosis caused by ligands was the event responsible for the process in which receptors are inactivated.
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Bioorthogonal chemistry refers to chemical reactions occurring inside living systems without reacting with naturally present cellular components. In supramolecular chemistry the notion of orthogonality refers to the possibility of two or more supramolecular, often non-covalent, interactions being compatible; reversibly forming without interference from the other. In analytical chemistry, analyses are "orthogonal" if they make a measurement or identification in completely different ways, thus increasing the reliability of the measurement. Orthogonal testing thus can be viewed as "cross-checking" of results, and the "cross" notion corresponds to the etymologic origin of orthogonality.
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Among the most common uses of streptavidin are the purification or detection of various biomolecules. The strong streptavidin- biotin interaction can be used to attach various biomolecules to one another or onto a solid support. Harsh conditions are needed to break the streptavidin-biotin interaction, which often denatures the protein of interest being purified. However, it has been shown that a short incubation in water above 70 °C will reversibly break the interaction (at least for biotinylated DNA) without denaturing streptavidin, allowing re-use of the streptavidin solid support.
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Photolyases bind complementary DNA strands and break certain types of pyrimidine dimers that arise when a pair of thymine or cytosine bases on the same strand of DNA become covalently linked. The bond length of this dimerization is shorter than the bond length of normal B-DNA structure which produces an incorrect template for replication and transcription. The more common covalent linkage involves the formation of a cyclobutane bridge. Photolyases have a high affinity for these lesions and reversibly bind and convert them back to the original bases.
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Photochromic units have been employed extensively in supramolecular chemistry. Their ability to give a light- controlled reversible shape change means that they can be used to make or break molecular recognition motifs, or to cause a consequent shape change in their surroundings. Thus, photochromic units have been demonstrated as components of molecular switches. The coupling of photochromic units to enzymes or enzyme cofactors even provides the ability to reversibly turn enzymes "on" and "off", by altering their shape or orientation in such a way that their functions are either "working" or "broken".
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The moenomycin family functions as an antibiotic by reversibly binding bacterial transglycosylases, essential enzymes that catalyze the extension of the glycan chain of the cell wall to form a stable peptidoglycan layer. The moenomycins mimic and thus compete with the natural substrate of the enzyme, inhibiting growth of the cell wall. Compromise of the wall results in leakage of cell contents, and ultimately cell death. The moenomycins are the only known active site inhibitors of these enzymes, which in lies their promise as human antibiotics given pathogenic bacteria have not yet widely evolved resistance.
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Equilibrium gel is similar to any gel in the way that it is a colloid in which the disperse phase has combined with the dispersion medium to produce a semisolid material. The difference with equilibrium gel is that it will not separate over time into two separate phase like all other gels. In a study taking place over seven years, scientist concluded that colloidal clays at slightly higher concentrations evolved reversibly and continuously from the empty liquid state to an arrested structure. From this observed properties the name equilibrium gel was derived.
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A single-atom transistor is a device that can open and close an electrical circuit by the controlled and reversible repositioning of one single atom. The single-atom transistor was invented and first demonstrated in 2004 by Prof. Thomas Schimmel and his team of scientists at the Karlsruhe Institute of Technology (former University of Karlsruhe). By means of a small electrical voltage applied to a control electrode, the so-called gate electrode, a single silver atom is reversibly moved in and out of a tiny junction, in this way closing and opening an electrical contact.
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Vaborbactam is a boronic acid β-lactamase inhibitor with a high affinity for serine β-lactamases, including Klebsiella pneumoniae carbapenemase (KPC). Vaborbactam inhibits a variety of β-lactamases, exhibiting a 69 nM Ki against the KPC-2 carbapenemase and even lower inhibition constants against CTX-M-15 and SHV-12. Boronic acids are unusual in their ability to reversibly form covalent bonds with alcohols such as the active site serine in a serine carbapenemase. This property enables them to function as transition state analogs of serine carbapenemase-catalyzed lactam hydrolysis and thereby inhibit these enzymes.
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It is quite common that biomolecules, such as DNA, protein and the like, come into being through various noncovalent interactions in biological system. Likewise, supramolecular polymers assembles themself via a combination of noncovalent interactions. Such formation manner endows supramolecular polymers with features, being more sensitive to external stimuli and able to render reversibly dynamic changes in structures and functions. By modifying monomeric units of supramolecular polymers with water-soluble pendants, bioactive moieties as well as biomarkers, supramolecular polymers can realize various kinds of functions and applications in biomedical field.
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Sometimes the memory requirement for a table needs to be minimized. One way to reduce memory usage in chaining methods is to eliminate some of the chaining pointers or to replace them with some form of abbreviated pointers. Another technique was introduced by Donald Knuth and is called quotienting. For this discussion assume that the key, or a reversibly-hashed version of that key, is an integer m from {0, 1, 2, ..., M-1} and the number of buckets is N. m is divided by N to produce a quotient q and a remainder r.
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Philanthotoxins are components of the venom of the Egyptian solitary wasp Philanthus triangulum, commonly known as the European beewolf. Philanthotoxins are polyamine toxins, a group of toxins isolated from the venom of wasps and spiders which immediately but reversibly paralyze their prey.. δ-philanthotoxin, also known as PhTX-433, is the most active philanthotoxin that can be refined from the venom. PhTX-433 functions by non-selectively blocking excitatory neurotransmitter ion channels, including nicotinic acetylcholine receptors (nAChRs) and ionotropic glutamate receptors (iGluRs). Synthetic analogues, including PhTX-343 and PhTX-12, have been developed to improve selectivity.
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Like amoebae, the plasmodium can consume whole microbes, but also readily grows axenically in liquid cultures, nutrient agar plates and on nutrient-moistened surfaces. When nutrients are provided uniformly, the nuclei in the plasmodium divide synchronously, accounting for the interest in using P. polycephalum as a model organism to study the cell cycle, or more specifically the nuclear division cycle. When the plasmodium is starved, it has two alternative developmental pathways. In the dark, the plasmodium typically differentiates reversibly into a dormant “sclerotium” (the same term is used for dormant forms of fungal mycelia, but the myxomycete sclerotium is a very different structure).
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Docetaxel binds to microtubules reversibly with high affinity and has a maximum stoichiometry of 1 mole docetaxel per mole tubulin in microtubules. This binding stabilizes microtubules and prevents depolymerisation from calcium ions, decreased temperature and dilution, preferentially at the plus end of the microtubule. Docetaxel has been found to accumulate to higher concentration in ovarian adenocarcinoma cells than kidney carcinoma cells, which may contribute to the more effective treatment of ovarian cancer by docetaxel. It has also been found to lead to the phosphorylation of oncoprotein bcl-2, which is apoptosis- blocking in its oncoprotein form.
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Like CEEs as a whole, 17β-dihydroequilin has disproportionate effects in certain tissues such as the liver and uterus. Equilin, the second major component of conjugated estrogens after estrone, is reversibly transformed into 17β-dihydroequilin analogously to the transformation of estrone into estradiol. However, whereas the balance of mutual interconversion of estrone and estradiol is largely shifted in the direction of estrone, it is nearly equal in the case of equilin and 17β-dihydroequilin. As such, although 17β-dihydroequilin is only a minor constituent of CEEs, it is, along with estradiol, the most important estrogen relevant to the estrogenic activity of the medication.
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Some researchers prefer to define the term “photoinhibition” so that it contains all reactions that lower the quantum yield of photosynthesis when a plant is exposed to light. In this case, the term "dynamic photoinhibition" comprises phenomena that reversibly down-regulate photosynthesis in the light and the term "photodamage" or "irreversible photoinhibition" covers the concept of photoinhibition used by other researchers. The main mechanism of dynamic photoinhibition is non- photochemical quenching of excitation energy absorbed by PSII. Dynamic photoinhibition is acclimation to strong light rather than light-induced damage, and therefore "dynamic photoinhibition" may actually protect the plant against "photoinhibition".
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Clockwise from top left: D-shaped wire gate, D-shaped straight gate, oval straight gate, pear-shaped auto locker, D-shaped screw locker. Center is a standard carabiner rating. Using a carabiner A carabiner or karabiner () is a specialized type of shackle, a metal loop with a spring-loaded gate used to quickly and reversibly connect components, most notably in safety-critical systems. The word is a shortened form of Karabinerhaken (or also short Karabiner), a German phrase for a "spring hook" used by a carbine rifleman, or carabinier, to attach his carabin to a belt or bandolier.
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This complex was synthesized using the WLA and HILR processes, and it can be reversibly activated and deactivated through small-molecule or elemental anion effector reactions that assemble and disassemble the trilayer structures. In the recent Al(III)-salen example, the polymerization of ε-caprolactone could be turned on and off based on the ancillary ligands and abstraction agents added to the system. Unlike in previous catalytic structures that utilized bimetallic systems, utilizing the tri-layer motif allows for the incorporation of a monometallic catalyst, opening the scope of potential catalysts that can be employed in these types of structures.
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The most prominent is that it reversibly blocks the action of adenosine on its receptors and consequently prevents the onset of drowsiness induced by adenosine. Caffeine also stimulates certain portions of the autonomic nervous system. Caffeine is a bitter, white crystalline purine, a methylxanthine alkaloid, and is chemically related to the adenine and guanine bases of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). It is found in the seeds, nuts, or leaves of a number of plants native to Africa, East Asia and South America, and helps to protect them against predator insects and to prevent germination of nearby seeds.
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The bioremediation potential of L. sphaericus has been widely studied: strains with chromate reduction capacity have been isolated from different contaminated environments and naturally metal-rich soils. The strain JG-A12, isolated from uranium-mining waste piles in Germany, is also able to reversibly bind aluminium, cadmium, copper, lead and uranium. Different studies have shown that this ability is due to the presence of a proteinaceous surface covering these cells, called the S-layer, which is able to bind high quantities of heavy metals in saline solutions. The biotechnological potential among Colombian isolates IV(4)10 and OT4b.
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Baricitinib is a Janus kinase (JAK) inhibitor that reversibly inhibits Janus kinase 1 with a half maximal inhibitory concentration (IC50) of 5.9 nM and Janus kinase 2 with an IC50 of 5.7 nM. Tyrosine kinase 2, which belongs to the same enzyme family, is affected less (IC50 = 53 nM), and Janus kinase 3 far less (IC50 > 400 nM). Via a signal transduction pathway involving STAT proteins, this ultimately modulates gene expression in immunological cells. Other JAK inhibitors include tofacitinib, which is indicated for the treatment of rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis; fedratinib, and ruxolitinib.
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Artificial muscles, also known as muscle-like actuators, are materials or devices that mimic natural muscle and can change their stiffness, reversibly contract, expand, or rotate within one component due to an external stimulus (such as voltage, current, pressure or temperature). The three basic actuation responses– contraction, expansion, and rotation can be combined together within a single component to produce other types of motions (e.g. bending, by contracting one side of the material while expanding the other side). Conventional motors and pneumatic linear or rotary actuators do not qualify as artificial muscles, because there is more than one component involved in the actuation.
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More recently he has demonstrated thermally initiated microemulsion polymerization in bicontinuous microemulsions, wherein the expansion of the correlation length was only 20% relative to the precursor microemulsion, surpassing competitive attempts by two orders of magnitude. In more recent years, he has become a leading innovator in the fields of stimuli responsive polymers and polymerized ionic liquids. Microemulsion polymerization of ionic liquid surfactant acrylates was used to produce transparent gels that reversibly undergo spinodal decomposition to open cell membranes and monoliths. Related nanolatexes have been formulated that appear to be the first experimental realizations of osmotic spheres.
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The metal has a number of different oxidation states that allows it to abstract a halide from the organohalide, creating a radical that then starts free radical polymerization. After inititation and propagation, the radical on the active chain terminus is reversibly terminated (with the halide) by reacting with the catalyst in its higher oxidation state. Thus, the redox process gives rise to an equilibrium between dormant (polymer-halide) and active (polymer-radical) chains. The equilibrium is designed to heavily favor the dormant state, which effectively reduces the radical concentration to a sufficiently low level to limit bimolecular coupling.
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The product of the cleavage of the carbamate group of methiocarb is methylcarbamic acid which is bound to cholinesterase after the reaction. The normal function of choline esterase is to cleave the acetyl-choline bond which results in the binding of acetic acid to choline sterase which is a fast reversible reaction. The carbamic acid also reversibly binds but the hydrolysis of the bond is slower and therefore the acid inhibits the function of choline sterase which results in elevated choline esterase levels. In comparison: organophosphates inhibit irreversibly and will therefore inhibit the acetylcholinesterase even more.
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In biochemistry, activation, specifically called bioactivation, is where enzymes or other biologically active molecules acquire the ability to perform their biological function, such as inactive proenzymes being converted into active enzymes that are able to catalyze their substrates' reactions into products. Bioactivation may also refer to the process where inactive prodrugs are converted into their active metabolites, or the toxication of protoxins into actual toxins. An enzyme may be reversibly or irreversibly bioactivated. A major mechanism of irreversible bioactivation is where a piece of a protein is cut off by cleavage, producing an enzyme that will then stay active.
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After this first purification step, a second type of bead (coated with calmodulin) is added to the released proteins which binds reversibly to the remaining piece of the TAP tag still on the proteins. The beads are again separated by centrifugation, further removing contaminants as well as the TEV protease. Finally, the beads are released by EGTA, leaving behind the native eluate containing only the protein of interest, its bound protein partners and the remaining CBP piece of the TAP tag. The native eluate can then be analyzed using gel electrophoresis and mass spectrometry to identify the protein's binding partners.
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Besides this, his group also created switching biomimetic hydrogels showing enzyme like activity (gelzymes). Achieving self-healing in permanently cross-linked hydrogels had remained elusive because of the presence of water and irreversible cross- links. Mashelkar and co-workers demonstrated for the first time that permanently cross-linked hydrogels can be engineered to exhibit self-healing in an aqueous environment. Mashelkar and co-workers demonstrated for the first time a novel enzyme mimicking hydrogel (gelzyme) in the form of a polymeric chymotrypsin mimic, whose hydrolytic activity could be rapidly, precisely and reversibly triggered on / off by UV light and pH.
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Female wasps of this species were reported to sting a cockroach (specifically a Periplaneta americana, Periplaneta australasiae, or Nauphoeta rhombifolia) twice, delivering venom. Researchers using radioactive labeling demonstrated that the wasp stings precisely into specific ganglia of the roach. It delivers an initial sting to a thoracic ganglion and injects venom to mildly and reversibly paralyze the front legs of its victim. A biochemically-induced transient paralysis takes over the cockroach, where the temporary loss of mobility facilitates the second venomous sting at a precise spot in the victim's head ganglia (brain), in the section that controls the escape reflex.
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The selectivity of hydrogenation can reach 97% at 7 MPa and 130 °C-150 °C. Although N-Heterocyles can optimize the unfavorable thermodynamic properties of cycloalkanes, a lot of issues remain unsolved, such as high cost, high toxicity and kinetic barriers etc. The imidazolium ionic liquids such alkyl(aryl)-3-methylimidazolium N-bis(trifluoromethanesulfonyl)imidate salts can reversibly add 6–12 hydrogen atoms in the presence of classical Pd/C or Ir0 nanoparticle catalysts and can be used as alternative materials for on-board hydrogen-storage devices. These salts can hold up to 30 g L−1 of hydrogen at atmospheric pressure.
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Another potential solid-state refrigeration technique and a relatively new area of study comes from a special property of super elastic materials. These materials undergo a temperature change when experiencing an applied mechanical stress (called the elastocaloric effect). Since super elastic materials deform reversibly at high strains, the material experiences a flattened elastic region in its stress-strain curve caused by a resulting phase transformation from an austenitic to a martensitic crystal phase. When a super elastic material experiences a stress in the austenitic phase, it undergoes an exothermic phase transformation to the martensitic phase, which causes the material to heat up.
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Schematic diagram of normal sinus rhythm for a human heart as seen on an electrocardiogram. Ajmaline was first discovered to lengthen the refractory period of the heart by blocking sodium ion channels, but it has also been noted that it is also able to interfere with the hERG (human Ether-a-go-go-Related Gene) potassium ion channel. In both cases, Ajmaline causes the action potential to become longer and ultimately leads to bradycardia. When ajmaline reversibly blocks hERG, repolarization occurs more slowly because it is harder for potassium to get out due to less unblocked channels, therefore making the RS interval longer.
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Twilight anesthesia is also known as twilight sleep and confers an easy awakening and a speedy recovery time by for patient. Anesthesia is used to control pain by using medicines that reversibly block nerve conduction near the site of administration, therefore, generating a loss of sensation at the area administered. Close monitoring by the Anesthesia Provider will sometimes be provided, to help keep the patient comfortable during a medical procedure, along with other drugs to help relax the body. It can also help control breathing, blood pressure, blood flow, and heart rate and rhythm, when needed.
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Many different types of tissue stem cells exist, including muscle stem cells (MuSCs), neural stem cells (NSCs), intestinal stem cells (ISCs), and many others. Stem cell quiescence has been recently suggested to be composed of two distinct functional phases, G0 and an ‘alert’ phase termed GAlert. Stem cells are believed to actively and reversibly transition between these phases to respond to injury stimuli and seem to gain enhanced tissue regenerative function in GAlert. Thus, transition into GAlert has been proposed as an adaptive response that enables stem cells to rapidly respond to injury or stress by priming them for cell cycle entry.
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Due to the crucial role of base, specific amines must be added in excess or as solvent for the reaction to proceed. It has been discovered that secondary amines such as piperidine, morpholine, or diisopropylamine in particular can react efficiently and reversibly with trans-RPdX(PPh3)2 complexes by substituting one PPh3 ligand. The equilibrium constant of this reaction is dependent on R, X, a factor for basicity, and the amine's steric hindrance. The result is competition between the amine and the alkyne group for this ligand exchange, which is why the amine is generally added in excess to promote preferential substitution.
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Tolcapone selectively and reversibly binds to the catalytic site of COMT in both the periphery and the central nervous system (CNS) with greater affinity than any of the three catecholamines, including levodopa. It thereby prevents the 3-O-methylation of levodopa by COMT in the periphery, which produces 3-O-methyldopa, a major metabolite that competes with levodopa to cross the blood–brain barrier. More of the levodopa that is administered reaches the CNS. Additionally, levodopa that has already reached the CNS, after being converted to dopamine, will not be degraded as quickly when tolcapone inhibits COMT activity.
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A site for site-specific conjugation is facilitated by introduction of a single cysteine at a desired position, therefore this engineered protein can be used to conjugate to radionuclides such as Technetium-99m and Indium-111 to visualize receptor-overexpressing tumors. A number of different Affibody molecules have been produced by chemical synthesis. Since they do not contain cysteines or disulfide bridges, they fold spontaneously and reversibly into the correct three-dimensional structures when the protection groups are removed after synthesis. In some studies, temperatures above the melting temperature have been used, with retained binding properties following return to ambient conditions.
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Forisomes function as valves in sieve tubes of the phloem system, by reversibly changing shape between low-volume ordered crystalloid spindles and high-volume disordered spherical conformations. The change from ordered to disordered conformation involves tripling of the protein's volume, loss of birefringence present in the crystalline phase, 120% radial expansion and 30% longitudinal shrinkage. In Vicia it was shown that forisomes are associated to the endoplasmic reticulum at sieve plates. There are evidences that the forisomes's behavior could depend on Ca2+ changes provoked by Ca2+-permeable ion channels, located on the endoplasmic reticulum and plasma membrane of sieve elements.
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If an attacker gains access to the password file, then if it is stored as plain text, no cracking is necessary. If it is hashed but not salted then it is vulnerable to rainbow table attacks (which are more efficient than cracking). If it is reversibly encrypted then if the attacker gets the decryption key along with the file no cracking is necessary, while if he fails to get the key cracking is not possible. Thus, of the common storage formats for passwords only when passwords have been salted and hashed is cracking both necessary and possible.
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More specifically, total entropy is conserved in a reversible process and not conserved in an irreversible process. For example, in the Carnot cycle, while the heat flow from the hot reservoir to the cold reservoir represents an increase in entropy, the work output, if reversibly and perfectly stored in some energy storage mechanism, represents a decrease in entropy that could be used to operate the heat engine in reverse and return to the previous state, thus the total entropy change is still zero at all times if the entire process is reversible. An irreversible process increases entropy.
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To ensure the production of the kinetic product, a slight excess (1.1 equiv) of lithium diisopropylamide is used, and the ketone is added to the base at –78 °C. Because the ketone is quickly and quantitatively converted to the enolate and base is present in excess at all times, the ketone is unable to act as a proton shuttle to catalyze the gradual formation of the thermodynamic product. A weaker base such as an alkoxide, which reversibly deprotonates the substrate, affords the more thermodynamically stable benzylic enolate. Enolates can be trapped by acylation and silylation, which occur at oxygen.
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Also there may be more complicated relationships: Compound A could reversibly but quickly react to substance B (with speed k1) or irreversible but slow (k1> k−1 >> k2) to substance C: :B <=> A ->[{k_2}] C Thermodynamic and kinetic product. Assuming that the reaction to substance C is irreversible, as it is thermodynamically very stable. In this case, B is the kinetic and C is the thermodynamic product of the reaction (see also here). If the reaction is carried out at low temperatures and stopped after a short time, it is spoken of kinetic control, primarily the kinetic product B would be formed.
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Therefore, a different approach is taken This is an example of a controlled/living cationic polymerization. Note that the "termination" step has been placed in equilibrium with an "initiation" step in either direction. Nu: is a weak nucleophile that can reversibly leave, while the MXn is a weak Lewis acid M bound to a halogen X to generate the carbocation. In this example, the carbocation is generated by the addition of a Lewis acid (co-initiator, along with the halogen "X" already on the polymer – see figure), which ultimately generates the carbocation in a weak equilibrium.
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Electrostatic properties of cowpea chlorotic mottle virus The assembly of a virus is key to its efficacy as it needs to be both stable enough to protect its genome before entry into the cell and labile enough to release its genetic contents into target cell as it disassembles. The single stranded RNA is threaded through small pores already present in the capsid. At a neutral pH, the capsid protein reversibly binds to RNA forming a pre-capsid complex. This consists of RNA surrounded by enough capsid proteins (CP) to neutralize the negative charges of the RNA phosphate backbone.
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Anastrozole works by reversibly binding to the aromatase enzyme, and through competitive inhibition blocks the conversion of androgens to estrogens in peripheral (extragonadal) tissues. The medication has been found to achieve 96.7% to 97.3% inhibition of aromatase at a dosage of 1 mg/day and 98.1% inhibition of aromatase at a dosage of 10 mg/day in humans. As such, 1 mg/day is considered to be the minimal dosage required to achieve maximal suppression of aromatase with anastrozole. This decrease in aromatase activity results in an at least 85% decrease in estradiol levels in postmenopausal women.
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The enzyme UDP-glucose 4-epimerase (), also known as UDP-galactose 4-epimerase or GALE, is a homodimeric epimerase found in bacterial, fungal, plant, and mammalian cells. This enzyme performs the final step in the Leloir pathway of galactose metabolism, catalyzing the reversible conversion of UDP-galactose to UDP-glucose. GALE tightly binds nicotinamide adenine dinucleotide (NAD+), a co-factor required for catalytic activity. Additionally, human and some bacterial GALE isoforms reversibly catalyze the formation of UDP-N- acetylgalactosamine (UDP-GalNAc) from UDP-N-acetylglucosamine (UDP-GlcNAc) in the presence of NAD+, an initial step in glycoprotein or glycolipid synthesis.
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The four- coordinated square planar arrangement in the starting complex converts to an octahedral, six-coordinate product. Vaska's complex undergoes oxidative addition with conventional oxidants such as halogens, strong acids such as HCl, and other molecules known to react as electrophiles, such as iodomethane (CH3I). Vaska's complex binds O2 reversibly: :IrCl(CO)[P(C6H5)3]2 \+ O2 ⇌ IrCl(CO)[P(C6H5)3]2O2 The dioxygen ligand is bonded to Ir by both oxygen atoms, called side-on bonding. In myoglobin and hemoglobin, by contrast, O2 binds end-on, attaching to the metal via only one of the two oxygen atoms.
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Pyr1 (LIMINIB) is an organic compound composed of carbon, hydrogen, oxygen and nitrogen that inhibits the enzyme LIM kinase. It was recently discovered by the Cure and Inserm Institute, CNRS and CEA, in collaboration with British and Australian investigators. The studies in vitro and with animals, published in Cancer Research, prove that this molecule has a completely new mechanism of action that could be used against chemotherapy resistant cells, providing a new alternative treatment to cancer that does not have major side effects. Pyr1 reversibly stabilizes microtubules, blocks actin microfilament dynamics and inhibits cell motility in vitro.
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Pseutarin-C is a procoagulant in the laboratory, but ultimately an anticoagulant in snakebite victims, as the prothrombin is used up and coagulopathy and spontaneous bleeding set in. Another agent, textilinin, is a Kunitz-like serine protease inhibitor that selectively and reversibly inhibits plasmin. A 2006 study comparing the venom components of eastern brown snakes from Queensland with those from South Australia found that the former had a stronger procoagulant effect and greater antiplasmin activity of textilinin. The venom also contains pre- and postsynaptic neurotoxins; textilotoxin is a presynaptic neurotoxin, at one stage considered the most potent recovered from any land snake.
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Moreover, plasmid DNA formed with the reannealing of individual strands was found to be similar to native plasmid in its properties. These findings showed that two strands of a plasmid DNA can be reversibly separated into individual strands and contradicted the Watson and Crick model of DNA structure. Kumar's report received serious criticism, including from You Cheng Xu of the UT Southwestern Medical Center at Dallas, who wrote that Kumar is "completely wrong" and that the evidence presented "cannot support his conclusion."[36] Xu published an article in the journal Symmetry in November 2019 that challenging the double helix model.[37].
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Uranium metal heated to reacts with hydrogen to form uranium hydride. Even higher temperatures will reversibly remove the hydrogen. This property makes uranium hydrides convenient starting materials to create reactive uranium powder along with various uranium carbide, nitride, and halide compounds.. Two crystal modifications of uranium hydride exist: an α form that is obtained at low temperatures and a β form that is created when the formation temperature is above 250 °C. Uranium carbides and uranium nitrides are both relatively inert semimetallic compounds that are minimally soluble in acids, react with water, and can ignite in air to form .
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Based on thermodynamic principles, thermoclines can be determined to establish the spread of cooling from particular cooling surfaces. Therefore, for each cooling device with a known and consistent surface area, the temperature can be set at the same value for each trial or experiment to generate the same thermoclines and replicate the same volume of deactivation. Therefore, specifically selected regions of tissue can be reversibly deactivated in a controlled and reproducible way. 20°C has been found to be the critical temperature for active neuronal signals; below this temperature, afferent signals cannot activate neurons and the tissue is considered deactivated.
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The Aβ monomer generally assumes an α-helical formation in aqueous solution, but can reversibly transition between α-helix and β-sheet structures at varying polarities. Atomic force microscopy captured images of Aβ channel structures that facilitated calcium uptake and subsequent neuritic degeneration. Molecular dynamics simulations of Aβ in lipid bilayers suggest that Aβ adopts a β-sheet-rich structure within lipid bilayers that gradually evolves to result in a wide variety of relaxed channel conformations. In particular, data support the organization of Aβ channels in β-barrels, structural formations commonly seen in transmembrane pore-forming toxins including anthrax.
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One of the most common side effects of spironolactone is frequent urination. Other general side effects include dehydration, hyponatremia (low sodium levels), mild hypotension (low blood pressure), ataxia (muscle incoordination), drowsiness, dizziness, dry skin, and rashes. Because of its antiandrogenic activity, spironolactone can, in men, cause breast tenderness, gynecomastia (breast development), feminization in general, and demasculinization, as well as sexual dysfunction including loss of libido and erectile dysfunction, although these side effects are usually confined to high doses of spironolactone. At very high doses (400 mg/day), spironolactone has also been associated with testicular atrophy and reversibly reduced fertility, including semen abnormalities such as decreased sperm count and motility in men.
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After periods of post-doctoral research at the University of Newcastle upon Tyne and the University of Manchester in 1965 and 1966, Robinson was a faculty member in the Department of Chemistry at the University of Otago in Dunedin from 1967 to 2006. He became a professor in 1985 and the Mellor Professor of Chemistry in 1996, and served as the head of the Department of Chemistry from 1986 to 1998. When he retired in 2006 he was made a professor emeritus. Building on his doctoral research, Robinson proposed that metal carbonyl clusters could participate in electron transfer reactions, and demonstrated that clusters are able to be reversibly reduced.
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Fuchter has also developed novel molecular photoswitches – molecules that can be cleanly and reversibly interconverted between two states using light – with a focus on heteroaromatic versions of azobenzene. The arylazopyrazole switches developed by Fuchter out perform the ubiquitous azobenzene switches, demonstrating complete photoswitching in both directions and thermal half-lives of the Z isomer of up to 46 years. Fuchter continues to apply these switches to a range of photoaddressable applications from photopharmacology to energy storage. Alongside his work on functional material discovery, Fuchter works in medicinal chemistry and develops small molecule ligands that can either inhibit or stimulate the activity of disease relevant proteins.
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Several types of metal oxides and sulfides can reversibly intercalate lithium cations at voltages between 1 and 2V against lithium metal with little difference between the charge and discharge steps. Specifically the mechanism of insertion involves lithium cations filling crystallographic vacancies in the host lattice with minimal changes to the bonding within the host lattice. This differentiates intercalation anodes from conversion anodes that store lithium by complete disruption and formation of alternate phases, usually as lithia. Conversion systems typically disproportionate to lithia and a metal (or lower metal oxide) at low voltages, < 1V vs Li, and reform the metal oxide at voltage > 2V, for example, CoO + 2Li --> Co+Li2O.
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Hence, color is an alternative method of identifying [PSI+] -- [PSI+] strains are white or pinkish in color, and [psi-] strains are red. A third method of identifying [PSI+] is by the presence of Sup35 in the pelleted fraction of cellular lysate. When exposed to certain adverse conditions, in some genetic backgrounds [PSI+] cells actually fare better than their prion-free siblings; this finding suggests that the ability to adopt a [PSI+] prion form may result from positive evolutionary selection. It has been speculated that the ability to convert between prion-infected and prion-free forms acts as an evolutionary capacitor to enable yeast to quickly and reversibly adapt in variable environments.
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In the late 70s Graf co-discovered several cell-derived oncogenes acquired by avian retroviruses, designated Mac (later changed into Myc), Erb and Myb. He found that several naturally occurring virus strains have acquired various pairwise combinations of oncogenes and that these cooperate to cause acute leukemia, an early example for the multigenic origin of cancers. He also showed that the transcription factor Myb can reversibly block the differentiation of white blood cells, one of the first demonstrations of induced cell fate changes. In his more recent research he showed that different types of specialized blood cells can be induced to convert into each other by forced transcription factor expression.
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An important substrate of the enzyme MAO is tyramine. MAOIs inhibit the enzyme either reversibly, in which MAO is inhibited only until the drug is cleared from the system, or irreversibly, in which the substrate binds permanently to the enzyme, rendering it inactive and effectively destroying it. Irreversible MAOIs are potentially more dangerous, because the body takes about two weeks to regenerate MAO enzymes to functional levels. Two subtypes of MAO exist: MAO-A and MAO-B; this is relevant to adrenergic storms, as there are significant differences between the two types, such as their differential expression throughout the body, and range of substrates.
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To ensure the production of the kinetic product, a slight excess (1.1 equiv) of lithium diisopropylamide is used, and the ketone is added to the base at –78 °C. Because the ketone is quickly and quantitatively converted to the enolate and base is present in excess at all times, the ketone is unable to act as a proton shuttle to catalyze the gradual formation of the thermodynamic product. A weaker base such as an alkoxide, which reversibly deprotonates the substrate, affords the more thermodynamically stable benzylic enolate. An alternative to the weaker base is to use a strong base which is present at a lower concentration than the ketone.
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These amino acids are spaced out in each region's polypeptide sequence in such a way that when the sequence is coiled in a 3D alpha-helix, the leucine residues line up on the same side of the helix. This region of the alpha-helix- containing the leucines which line up- is called a ZIP domain, and leucines from each ZIP domain can weakly interact with leucines from other ZIP domains, reversibly holding their alpha-helices together (dimerization). When these alpha helices dimerize, the zipper is formed. The hydrophobic side of the helix forms a dimer with itself or another similar helix, burying the non-polar amino acids away from the solvent.
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The mycelia of this species, grown in laboratory culture, have also been shown to be bioluminescent. Early studies demonstrated that short-wave ultraviolet light (at a wavelength of 280 nm) reversibly inhibited the luminescence of P. stypticus mycelia, while longer wavelength (366 nm) ultraviolet was stimulatory. Further, the fungus exhibited a pronounced diurnal periodicity, and maximum luminescence was noted between 6 and 9 pm, regardless as to whether the mycelial cultures were incubated in continuous light, continuous darkness, or a normal day-night cycle. The mycelia of P. stipticus grown submerged in liquid were non- luminescent, but became luminescent while growing on solid substrata.
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The obtainable energy density is predicted to be highest under tensile loading, with an energy density in the springs themselves about 2500 times greater than the energy density that can be reached in steel springs, and 10 times greater than the energy density of lithium-ion batteries. The process of elastic energy storage in a CNT involves deforming it under an applied load. On removal of the applied load the energy released from the CNT can be used to perform mechanical work. A CNT has the ability to deform reversibly and a spring made from it can undergo repeated charge-discharge cycles without fatigue.
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Neptunium hexafluoride is stable in dry air. However, it reacts vigorously with water, including atmospheric moisture, to form the water-soluble neptunyl fluoride (NpO2F2) and hydrofluoric acid (HF). : + 2 → + 4 It can be stored at room temperature in a quartz or pyrex glass ampoule, provided that there are no traces of moisture or gas inclusions in the glass and any remaining HF has been removed. NpF6 and PuF6 are light- sensitive, decomposing to the corresponding tetrafluoride and fluorine. NpF6 forms complexes with alkali metal fluorides: with caesium fluoride (CsF) it forms CsNpF6 at 25 °C, and with sodium fluoride it reacts reversibly to form Na3NpF8.
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A diagram depicting a use of dynamic combinatorial library to select an optimal receptor. In contrast to traditional combinatorial synthesis where a library of catalysts were first generated and later screened (as in the two above approaches), dynamic combinatorial library approach utilizes a mixture of multicomponent building blocks that reversibly form library of catalysts. With out a template, the library consists of a roughly equal mixture of different combination of building blocks. In the presence of a template which is either a starting material or a TSA, the combination that provides the best binding to the template is thermodynamically favorable and thus that combination is more prevalent than other library members.
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Specifically, NO has been shown to play an important negative feedback regulatory role on NOS3, and therefore vascular endothelial cell function. This process, known formally as S-nitrosation (and referred to by many in the field as S-nitrosylation), has been shown to reversibly inhibit NOS3 activity in vascular endothelial cells. This process may be important because it is regulated by cellular redox conditions and may thereby provide a mechanism for the association between "oxidative stress" and endothelial dysfunction. In addition to NOS3, both NOS1 and NOS2 have been found to be S-nitrosated, but the evidence for dynamic regulation of those NOS isoforms by this process is less complete.
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One structure called MIL-73, with formula [Ni7(C4H2O4)4(OH)6·3H2O]·7H2O, crystallises in the monoclinic system with a=7.8597 b=18.8154 c=23.4377 β=92.029° unit cell volume V=3463.9 Å3. The structure consists of alternating layers of nickel hydroxide chains running in the b direction stacked side by side in the a direction, and succinate aligned in the c direction. Thermal decomposition resulted in stages of water loss at 45°, 60°, 110° (reversibly losing the .7H2O. More water is lost at 225° and total decomposition occurs at 280°C. Under 20K MIL-73 is ferrimagnetic. Another structure has formula [Ni7(C4H2O4)6(OH)2·2H2O]·2H2O.
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Hemoglobin reversibly binds to oxygen in the lungs when the pH is high, and the carbon dioxide concentration is low. When the situation is reversed (low pH and high carbon dioxide concentrations), hemoglobin will release oxygen into the tissues. This phenomenon, which states that hemoglobin's oxygen binding affinity is inversely proportional to both acidity and concentration of carbon dioxide, is known as the Bohr effect. The molecular mechanism behind this effect is the steric organization of the globin chain; a histidine residue, located adjacent to the heme group, becomes positively charged under acidic conditions (which are caused by dissolved CO2 in working muscles, etc.), releasing oxygen from the heme group.
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Pepsin may be inhibited by high pH (see Activity and stability) or by inhibitor compounds. Pepstatin is a low molecular weight compound and potent inhibitor specific for acid proteases with a Ki of about 10−10 M for pepsin. The statyl residue of pepstatin is thought to be responsible for pepstatin inhibition of pepsin; statine is a potential analog of the transition state for catalysis by pepsin and other acid proteases. Pepstatin does not covalently bind pepsin and inhibition of pepsin by pepstatin is therefore reversible. 1-bis(diazoacetyl)-2-phenylethane reversibly inactivates pepsin at pH 5, a reaction which is accelerated by the presence of Cu(II).
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Photoaffinity labeling is a technique used to attach "labels" to the active site of a large molecule, especially a protein. The "label" attaches to the molecule loosely and reversibly, and has an inactive site which can be converted using photolysis into a highly reactive form, which causes the label to bind more permanently to the large molecule via a covalent bond.Photoaffinity labelingPhotoaffinity labeling, Gold Book The technique was first described in the 1970s. Molecules that have been used as labels in this process are often analogs of complex molecules, in which certain functional groups are replaced with a photoreactive group, such as an azide, a diazirine or a benzophenone.
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NTX associates reversibly with K+ channels and thus decreases K+ permeability in brain synaptosomes. The location of the active site of NTX is not completely known yet. However, it is believed to be located close to the N-Terminal portion of the toxin as administration of synthetic-nonapeptide NTX1-9, which corresponds to the N-Terminal sequences of NTX, leads to symptoms of intoxication that are very similar to native NTX, while a second synthetic active fragment, corresponding to the C-Terminal of NTX, did not lead to symptoms of intoxication. Furthermore, the mode of action of NTX is thought to be concentration dependent.
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The energy dissipated within a medium as sound travels through it is analogous to the energy dissipated in electrical resistors or that dissipated in mechanical dampers for mechanical motion transmission systems. All three are equivalent to the resistive part of a system of resistive and reactive elements. The resistive elements dissipate energy (irreversibly into heat) and the reactive elements store and release energy (reversibly, neglecting small losses). The reactive parts of an acoustic medium are determined by its bulk modulus and its density, analogous to respectively an electrical capacitor and an electrical inductor, and analogous to, respectively, a mechanical spring attached to a mass.
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The Zultanski–Zhao–Stahl oxidative amide coupling is a reaction between a primary alcohol and an amine to form an amide. In the Zultanski–Zhao–Stahl reaction, a primary alcohol is oxidized to an aldehyde which, in the presence of an amine, reversibly forms a hemiaminal which is then irreversibly oxidized to the amide by the catalyst. The reaction is performed under an atmosphere of oxygen in the presence of 3Å molecular sieves using relatively high ABNO loading of 3 mol %. Optimal reaction conditions are substrate dependent, requiring specific copper(I) sources, ligands, and solvents depending on the structure of the starting alcohol and amines.
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When iodine dissolves in strong acids, such as fuming sulfuric acid, a bright blue paramagnetic solution including cations is formed. A solid salt of the diiodine cation may be obtained by oxidising iodine with antimony pentafluoride: :2 I2 \+ 5 SbF5 2 I2Sb2F11 \+ SbF3 The salt I2Sb2F11 is dark blue, and the blue tantalum analogue I2Ta2F11 is also known. Whereas the I–I bond length in I2 is 267 pm, that in is only 256 pm as the missing electron in the latter has been removed from an antibonding orbital, making the bond stronger and hence shorter. In fluorosulfuric acid solution, deep-blue reversibly dimerises below −60 °C, forming red rectangular diamagnetic .
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Other prescription drugs are also used, if other methods are not effective. Before the introduction of SSRIs, monoamine oxidase inhibitors (MAOIs) such as phenelzine were frequently used in the treatment of social anxiety. Evidence continues to indicate that MAOIs are effective in the treatment and management of social anxiety disorder and they are still used, but generally only as a last resort medication, owing to concerns about dietary restrictions, possible adverse drug interactions and a recommendation of multiple doses per day. A newer type of this medication, reversible inhibitors of monoamine oxidase subtype A (RIMAs) such as the drug moclobemide, bind reversibly to the MAO-A enzyme, greatly reducing the risk of hypertensive crisis with dietary tyramine intake.
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Affinity labels are a class of enzyme inhibitors that covalently bind to their target causing its inactivation. The hallmark of an affinity label is the use a targeting moiety to specifically and reversibly deliver a weakly reactive group to the enzyme that irreversibly binds to an amino acid residue. The targeting portion of the label often resembles the enzyme's natural substrate so that a similar mode of noncovalent binding is used prior to the covalent linkage. Their usefulness in medicine can be limited by the specificity of the first noncovalent binding step whereas indiscriminate action can be utilized for purposes such as affinity labeling - a technique for the validation of substrate-specific binding of compounds.
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Example of a T-REx system controlling the expression of shRNA Tetracycline- Controlled Transcriptional Activation is a method of inducible gene expression where transcription is reversibly turned on or off in the presence of the antibiotic tetracycline or one of its derivatives (e.g. doxycycline). Tetracycline-controlled gene expression is based upon the mechanism of resistance to tetracycline antibiotic treatment found in Gram-negative bacteria. In nature, the Ptet promoter expresses TetR, the repressor, and TetA, the protein that pumps tetracycline antibiotic out of the cell. The difference between Tet-On and Tet-Off is not whether the transactivator turns a gene on or off, as the name might suggest; rather, both proteins activate expression.
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Heating the carbonate, proceeds in a typical way for calcining, except that the material is partially oxidized: : 6 CoCO3 \+ O2 → 2 Co3O4 \+ 6 CO2 The resulting Co3O4 converts reversibly to CoO at high temperatures.G.A. El- Shobaky, A.S. Ahmad, A.N. Al-Noaimi and H.G. El-Shobaky Journal of Thermal Analysis and Calorimetry 1996, Volume 46, Number 6 , pp.1801-1808. online abstract Like most transition metal carbonates, cobalt carbonate is insoluble in water, but is readily attacked by mineral acids: :CoCO3 \+ 2 HCl + 5 H2O → [Co(H2O)6]Cl2 \+ CO2 It is used to prepare many coordination complexes. The reaction of cobalt(II) carbonate and acetylacetone in the presence of hydrogen peroxide gives tris(acetylacetonato)cobalt(III).
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Realizing the modest thermal conductivity enhancement in conventional nanofluids, a team of researchers at Indira Gandhi Centre for Atomic Research Centre, Kalpakkam developed a new class of magnetically polarizable nanofluids where the thermal conductivity enhancement up to 300% of basefluids is demonstrated. Fatty-acid-capped magnetite nanoparticles of different sizes (3-10 nm) have been synthesized for this purpose. It has been shown that both the thermal and rheological properties of such magnetic nanofluids are tunable by varying the magnetic field strength and orientation with respect to the direction of heat flow. Such response stimuli fluids are reversibly switchable and have applications in miniature devices such as micro- and nano-electromechanical systems.
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Glucose can exist in both a straight-chain and ring form. The aldehyde or ketone group of a straight-chain monosaccharide will react reversibly with a hydroxyl group on a different carbon atom to form a hemiacetal or hemiketal, forming a heterocyclic ring with an oxygen bridge between two carbon atoms. Rings with five and six atoms are called furanose and pyranose forms, respectively, and exist in equilibrium with the straight- chain form. During the conversion from straight-chain form to the cyclic form, the carbon atom containing the carbonyl oxygen, called the anomeric carbon, becomes a stereogenic center with two possible configurations: The oxygen atom may take a position either above or below the plane of the ring.
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Catechol oxidase is a copper oxidase that contains a type 3 di-copper cofactor and catalyzes the oxidation of ortho-diphenols into ortho-quinones coupled with the reduction of molecular oxygen to water. It is present in a variety of species of plants and fungi including Ipomoea batatas (sweet potato) and Camellia sinensis (Indian tea leaf). Metalloenzymes with type 3 copper centers are characterized by their ability to reversibly bind dioxygen at ambient conditions. In plants, catechol oxidase plays a key role in enzymatic browning by catalyzing the oxidation of catechol to o-quinone in the presence of oxygen, which can rapidly polymerize to form the melanin that grants damaged fruits their dark brown coloration.
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As disulfide bonds can be reversibly reduced and re-oxidized, the redox state of these bonds has evolved into a signaling element. In chloroplasts, for example, the enzymatic reduction of disulfide bonds has been linked to the control of numerous metabolic pathways as well as gene expression. The reductive signaling activity has been shown, thus far, to be carried by the ferredoxin thioredoxin system, channeling electrons from the light reactions of photosystem I to catalytically reduce disulfides in regulated proteins in a light dependent manner. In this way chloroplasts adjust the activity of key processes such as the Calvin–Benson cycle, starch degradation, ATP production and gene expression according to light intensity.
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John Varley, who also came to prominence in the 1970s, is another writer who examined sexual themes in his work. In his "Eight Worlds" suite of stories and novels, humanity has achieved the ability to change sex quickly, easily and completely reversibly – leading to a casual attitude with people changing their sex back and forth as the sudden whim takes them. Homophobia is shown as initially inhibiting the uptake of this technology, as it engenders drastic changes in relationships, with bisexuality becoming the default mode for society. Sexual themes are central to the story "Options": a married woman, Cleo, living in King City, undergoes a change to male despite her husband's objections.
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A version of the catalytic cycle is shown below for the ortho borylation of hydrosilane compounds. Kinetic data show that an observed trisboryl complex coordinated to cyclooctene rapidly and reversibly dissociates cyclooctene to form a 16 electron trisboryl complex. In the case of using benzyldimethylsilane as a directing group it is proposed that benzyldimethylsilane reacts with the trisboryl iridium catalyst through reversible addition of the Si-H bond to the metal center, followed by selective ortho-C–H bond activation via oxidative addition and reductive elimination. Mechanism of hydrosilane Meta-Selective Borylation: Meta-Selective C–H borylation is an important synthetic transformation, which was discovered in 2002 by Smith III from Michigan State University, USA.
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BMR is a flexible trait (it can be reversibly adjusted within individuals), with, for example, lower temperatures generally resulting in higher basal metabolic rates for both birds and rodents. There are two models to explain how BMR changes in response to temperature: the variable maximum model (VMM) and variable fraction model (VFM). The VMM states that the summit metabolism (or the maximum metabolic rate in response to the cold) increases during the winter, and that the sustained metabolism (or the metabolic rate that can be indefinitely sustained) remains a constant fraction of the former. The VFM says that the summit metabolism does not change, but that the sustained metabolism is a larger fraction of it.
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The earliest genetically targeted method that used light to control rhodopsin- sensitized neurons was reported in January 2002, by Boris Zemelman and Gero Miesenböck, who employed Drosophila rhodopsin cultured mammalian neurons. In 2003, Zemelman and Miesenböck developed a second method for light-dependent activation of neurons in which single ionotropic channels TRPV1, TRPM8 and P2X2 were gated by photocaged ligands in response to light. Beginning in 2004, the Kramer and Isacoff groups developed organic photoswitches or "reversibly caged" compounds in collaboration with the Trauner group that could interact with genetically introduced ion channels. TRPV1 methodology, albeit without the illumination trigger, was subsequently used by several laboratories to alter feeding, locomotion and behavioral resilience in laboratory animals.
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There is significant interest in SiNWs for their unique properties and the ability to control size and aspect ratio with great accuracy. As yet, limitations in large-scale fabrication impede the uptake of this material in the full range of investigated applications. Combined studies of synthesis methods, oxidation kinetics and properties of SiNW systems aim to overcome the present limitations and facilitate the implementation of SiNW systems, for example, high quality vapor-liquid-solid–grown SiNWs with smooth surfaces can be reversibly stretched with 10% or more elastic strain, approaching the theoretical elastic limit of silicon, which could open the doors for the emerging “elastic strain engineering” and flexible bio-/nano- electronics.
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Because the simultaneous collision of three chemical species in a reactive orientation is improbable, the termolecular transition state is believed to be reached when the nucleophile attacks a reversibly-formed weak association of the alkyne and HCl. Such a mechanism is consistent with the predominantly anti addition (>15:1 anti:syn for the example shown) of the hydrochlorination product and the termolecular rate law, Rate = k[alkyne][HCl]2. In support of the proposed alkyne-HCl association, a T-shaped complex of an alkyne and HCl has been characterized crystallographically. 500x500pxIn contrast, phenylpropyne reacts by the AdE2ip ("addition, electrophilic, second-order, ion pair") mechanism to give predominantly the syn product (~10:1 syn:anti).
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On October 3, 2013, the company initially revealed that 2.9 million customers' sensitive and personal data was stolen in security breach which included encrypted credit card information. Adobe later admitted that 38 million active users have been affected and the attackers obtained access to their IDs and encrypted passwords, as well as to many inactive Adobe accounts. The company did not make it clear if all the personal information was encrypted, such as email addresses and physical addresses, though data privacy laws in 44 states require this information to be encrypted. A 3.8 GB file stolen from Adobe and containing 152 million usernames, reversibly encrypted passwords and unencrypted password hints was posted on AnonNews.org.
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A flow battery is a rechargeable fuel cell in which an electrolyte containing one or more dissolved electroactive elements flows through an electrochemical cell that reversibly converts chemical energy directly to electricity. Electroactive elements are "elements in solution that can take part in an electrode reaction or that can be adsorbed on the electrode." Additional electrolyte is stored externally, generally in tanks, and is usually pumped through the cell (or cells) of the reactor, although gravity feed systems are also known. Flow batteries can be rapidly "recharged" by replacing the electrolyte liquid (in a similar way to refilling fuel tanks for internal combustion engines) while simultaneously recovering the spent material for re-energization.
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In thermodynamics, the Gibbs free energy is a thermodynamic potential that can be used to calculate the maximum of reversible work that may be performed by a thermodynamic system at a constant temperature and pressure. The Gibbs free energy measured in joules in SI) is the maximum amount of non-expansion work that can be extracted from a thermodynamically closed system (can exchange heat and work with its surroundings, but not matter). This maximum can be attained only in a completely reversible process. When a system transforms reversibly from an initial state to a final state, the decrease in Gibbs free energy equals the work done by the system to its surroundings, minus the work of the pressure forces.
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What was previously the potential energy of the marble, will now reside in the increased heat energy of the marble-bowl system. This will be an application of the maximum entropy principle as set forth in the principle of minimum potential energy, since due to the heating effects, the entropy has increased to the maximum value possible given the fixed energy of the system. If, on the other hand, the marble is lowered very slowly to the bottom of the bowl, so slowly that no heating effects occur (i.e. reversibly), then the entropy of the marble and bowl will remain constant, and the potential energy of the marble will be transferred as energy to the surroundings.
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Subsequently, 3α-androstanediol and 3α-etiocholanediol are converted by 17β-HSD into androsterone and etiocholanolone, which is followed by their conjugation and excretion. 3β-Androstanediol and 3β-etiocholanediol can also be formed in this pathway when 5α-DHT and 5β-DHT are acted upon by 3β-HSD instead of 3α-HSD, respectively, and they can then be transformed into epiandrosterone and epietiocholanolone, respectively. A small portion of approximately 3% of testosterone is reversibly converted in the liver into androstenedione by 17β-HSD. In addition to conjugation and the 17-ketosteroid pathway, testosterone can also be hydroxylated and oxidized in the liver by cytochrome P450 enzymes, including CYP3A4, CYP3A5, CYP2C9, CYP2C19, and CYP2D6.
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Methanogenesis is a form of anaerobic respiration used by microbes, and microbial methanogenesis can occur in deep subsurface, marine sediments, freshwater bodies, etc. It appears that methane from deep subsurface and marine sediment is generally in internal isotopic equilibrium., while freshwater microbial methanogenesis expresses large kinetic isotope effect on methane clumped isotope composition. There are two possible explanations for this variance: firstly, substrate limitation may enhance the reversibility of methanogenesis, thus allowing methane to achieve internal isotopic equilibrium via rapid hydrogen exchange with water; secondly, activation of C-H bonds during anaerobic oxidation precedes reversibly such that C-H bonds are broken and reformed faster than the net rate of methane consumption and methane can be reequilibrated.
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Cartoon depicting the Heterotrimeric G-protein activation/deactivation cycle in the context of GPCR signaling When the receptor is inactive, the GEF domain may be bound to an also inactive α-subunit of a heterotrimeric G-protein. These "G-proteins" are a trimer of α, β, and γ subunits (known as Gα, Gβ, and Gγ, respectively) that is rendered inactive when reversibly bound to Guanosine diphosphate (GDP) (or, alternatively, no guanine nucleotide) but active when bound to guanosine triphosphate (GTP). Upon receptor activation, the GEF domain, in turn, allosterically activates the G-protein by facilitating the exchange of a molecule of GDP for GTP at the G-protein's α-subunit. The cell maintains a 10:1 ratio of cytosolic GTP:GDP so exchange for GTP is ensured.
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In addition, there is a spike in testosterone levels with testosterone enanthate and testosterone undecanoate that is not seen with testosterone buciclate, with which levels stay highly uniform and decrease very gradually and progressively. Testosterone buciclate can maintain testosterone levels in the normal male range for up to 20 weeks with a single intramuscular injection. Testosterone buciclate is able to reversibly and completely suppress spermatogenesis in men when used at sufficiently high dosages. As such, the results of clinical studies for use of testosterone buciclate as a male contraceptive were promising, and trials continued as late as 1995, but progress ultimately came to a standstill because the WHO was unable to find an industry partner willing to continue the development of the drug.
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Owing to their high tap density, high operating potentials and high capacities, cathodes based on sodium transition metal oxides have received the greatest attention. Furthermore, from a desire to keep costs low, significant research has been geared towards avoiding or reducing costly elements such as Co, Cr, Ni or V in the oxides. A P2-type Na2/3Fe1/2Mn1/2O2 oxide from earth-abundant Fe and Mn resources was demonstrated to reversibly store 190 mAh/g at average discharge voltage of 2.75 V vs Na/Na+ utilising the Fe3+/4+ redox couple in 2012 – such energy density was on par or better than commercial lithium-ion cathodes such as LiFePO4 or LiMn2O4. However, its sodium deficient nature meant sacrifices in energy density in practical full cells.
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Chondrodendron tomentosum, main source plant of 'Tube Curare' and principal source of D-tubocurarine (DTC), the alkaloid constituting medicinal curare. Strychnos toxifera, the Strychnos species which is the principal source of 'Calabash Curare' and its main active constituent - the alkaloid toxiferine Curare (/kʊˈrɑːri/ or /kjʊˈrɑːri/; koo-rah-ree or kyoo-rah-ree) is a common name for various plant extract alkaloid arrow poisons originating from Indigenous peoples in Central and South America. Used as a paralyzing agent for hunting and for therapeutic purposes, Curare only becomes active by a direct wound contamination by a poison dart or arrow or via injection. These poisons function by competitively and reversibly inhibiting the nicotinic acetylcholine receptor (nAChR), which is a subtype of acetylcholine receptor found at the neuromuscular junction.
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A grey striped six-on-one double-breasted suit with jetted pockets, a style popular in the 1980s A double-breasted garment is a coat, jacket, or vest with wide, overlapping front flaps which has on its front two symmetrical columns of buttons; by contrast, a single-breasted item has a narrow overlap and only one column of buttons. In most modern double-breasted coats, one column of buttons is decorative, while the other is functional. The other buttons, placed on the outside edge of the coat breast, allow the overlap to fasten reversibly, left lapel over right lapel. To strengthen the fastening, a functional inner-button, called the jigger (or anchor button), is usually added to parallel-fasten the over-lapped layers together from the inside.
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Bromine monochloride (BrCl), a red-brown gas, quite readily dissociates reversibly into bromine and chlorine at room temperature and thus also cannot be obtained pure, though it can be made by the reversible direct reaction of its elements in the gas phase or in carbon tetrachloride. Bromine monofluoride in ethanol readily leads to the monobromination of the aromatic compounds PhX (para-bromination occurs for X = Me, But, OMe, Br; meta-bromination occurs for the deactivating X = –CO2Et, –CHO, –NO2); this is due to heterolytic fission of the Br–F bond, leading to rapid electrophilic bromination by Br+. At room temperature, bromine trifluoride (BrF3) is a straw-coloured liquid. It may be formed by directly fluorinating bromine at room temperature and is purified through distillation.
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The Monstral blue found to coat the inside of copper vessels used to process phthalic acid derivatives had led to the discovery of Phthalocyanine in 1907. Attracted by the brilliance, stability and insolubility of this chromophore, attempts were made to reversibly modify it so that it would be carried into fabric in a solution and then easily precipitated (ingrained) into an unleachable but finely well dispersed deposit (hence the name "ingrain dyeing"). From this attempt, Alcian blue (Ingrain blue 1) was first synthesized by the ICI dyestuffs department under N. H. Haddock and C. Wood in the early 1940s and patented in 1947, originally as a textile dye. In 1950 it was used by Steedman as a selective dye for mucins.
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Unlike the case of estradiol, in which there is a rapid rise in its levels and which remain elevated in a plateau-like curve for many hours, levels of EE fall rapidly after peaking. This is thought to be because estrone and estrone sulfate can be reversibly converted back into estradiol and serve as a hormonally inert reservoir for estradiol, whereas the EE sulfate reservoir for EE is much smaller in comparison. In any case, due to the formation of EE sulfate, enterohepatic recirculation is involved in the pharmacokinetics of EE similarly to estradiol, although to a lesser extent. The contribution of enterohepatic recirculation to total circulating EE levels appears to be 12 to 20% or less, and is not observed consistently.
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Electrorheological (ER) fluids are suspensions of extremely fine non- conducting but electrically active particles (up to 50 micrometres diameter) in an electrically insulating fluid. The apparent viscosity of these fluids changes reversibly by an order of up to 100,000 in response to an electric field. For example, a typical ER fluid can go from the consistency of a liquid to that of a gel, and back, with response times on the order of milliseconds. The effect is sometimes called the Winslow effect after its discoverer, the American inventor Willis Winslow, who obtained a US patent on the effect in 1947: Winslow, W. M.: 'Method and means for translating electrical impulses into mechanical force', 25 March 1947 and wrote an article published in 1949.
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In the 3153A strain, a gene called SIR2 (for silent information regulator), which seems to be important for phenotypic switching, has been found. SIR2 was originally found in Saccharomyces cerevisiae (brewer's yeast), where it is involved in chromosomal silencing—a form of transcriptional regulation, in which regions of the genome are reversibly inactivated by changes in chromatin structure (chromatin is the complex of DNA and proteins that make chromosomes). In yeast, genes involved in the control of mating type are found in these silent regions, and SIR2 represses their expression by maintaining a silent-competent chromatin structure in this region.SIR2 gene overview The discovery of a C. albicans SIR2 implicated in phenotypic switching suggests it, too, has silent regions controlled by SIR2, in which the phenotype-specific genes may reside.
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A Logan plot (or Logan graphical analysis) is a graphical analysis technique based on the compartment model that uses linear regression to analyze pharmacokinetics of tracers involving reversible uptake. It is mainly used for the evaluation of nuclear medicine imaging data after the injection of a labeled ligand that binds reversibly to specific receptor or enzyme. In conventional compartmental analysis, an iterative method is used to fit the individual model parameters in the solution of a compartmental model of specific configuration to the measurements with a measured plasma time- activity curve that serves as an forcing (input) function, and the binding of the tracer can then be described. Graphical analysis is a simplified method that transforms the model equations into a linear equation evaluated at multiple time points and provides fewer parameters (i.e.
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Together, these observations tend to suggest that contrary to the prevailing wisdom that phenotype specification is highly deterministic, stochasticity may be a confounding factor in specifying cell fate. This thinking may also help explain how a given cell can reversibly switch phenotypes as seen in EMT and MET or for that matter, a drug-sensitive cell from developing resistance and switching back to drug sensitivity, or the transformation of a normal cell to a malignant one and its reversal to normalcy. Indeed, such stochasticity in phenotypic switching is also thought to underlie cellular differentiation, generation of induced pluripotent stem cells (iPS cells), tumor heterogeneity and emergence of cancer stem cells from non-stem cancer cells. Implicit in the MRK model, the PIN configuration contains information that can specify the cell's phenotype.
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In contrast to the established customary usage, "mixing" might be conducted reversibly at constant volume for each of two fixed masses of gases of equal volume, being mixed by gradually merging their initially separate volumes by use of two ideal semipermeable membranes, each permeable only to one of the respective gases, so that the respective volumes available to each gas remain constant during the merge. Either one of the common temperature or the common pressure is chosen to be independently controlled by the experimenter, the other being allowed to vary so as to maintain constant volume for each mass of gas. In this kind of "mixing", the final common volume is equal to each of the respective separate initial volumes, and each gas finally occupies the same volume as it did initially.Planck, M. (1897/1903).
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Then, by externally forcing ideally slowly the separating membranes together, back to contiguity, work is done on the mixed gases, fictively reversibly separating them again, so that heat is returned to the heat reservoir at constant temperature. Because the mixing and separation are ideally slow and fictively reversible, the work supplied by the gases as they mix is equal to the work done in separating them again. Passing from fictive reversibility to physical reality, some amount of additional work, that remains external to the gases and the heat reservoir, must be provided from an external source for this cycle, as required by the second law of thermodynamics, because this cycle has only one heat reservoir at constant temperature, and the external provision of work cannot be completely efficient.
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Matrix metalloproteases contain five conserved domains/sequence motifs: # Signal peptide sequence, which directs the enzyme into the rough endoplasmic reticulum during synthesis # Propeptide domain, which is cleaved to activate the enzyme # Catalytic domain, which contains the conserved Zn2+ binding region and mediates enzyme activity # Hemopexin domain, which provides the substrate specificity # Small hinge region, which allows the hemopexin domain to bring the substrate to the active core of the catalytic domain There is also a subfamily of the matrix metalloproteases, the membrane-type MMPs (MT-MMPs) which contain an additional transmembrane domain and a short cytoplasmic domain. After activation of MMPs by removal of the propeptide domain, their activity is regulated by TIMPs. TIMPs specifically and reversibly inhibit the activity of MMPs. So far there have been identified four members of the family, TIMP1–4.
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For this reason, it is used today in zinc–carbon and alkaline primaries. In the zinc–bromine flow battery the negative electrode reaction is the reversible dissolution/plating of zinc: : Zn_{(s)} <=> {Zn^2+}_{(aq)} + 2e^- At the positive electrode bromine is reversibly reduced to bromide (with a standard reduction potential of +1.087 V vs SHE): : {Br2_{(aq)}} + 2e^- <=> {2Br^-}_{(aq)} The overall cell reaction is therefore : {Zn_{(s)}} + Br2_{(aq)} <=> {2Br^-}_{(aq)} + {Zn^2+}_{(aq)} The measured potential difference is around 1.67 V per cell (slightly less than that predicted from the standard reduction potentials). The two electrode chambers of each cell are divided by a membrane (typically a microporous or ion-exchange variety). This helps to prevent bromine from reaching the positive electrode, where it would react with the zinc, causing the battery to self-discharge.
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Collison is regarded one of the leading researchers in electron paramagnetic resonance spectroscopy . For his significant contributions to the experimental and theoretical fundamentals of transition metal electron paramagnetic resonance, from bioinorganic chemistry to molecular materials, and for his contribution to the book Electron Paramagnetic Resonance (Volume 19), he received the Bruker Prize in 2020, which is one of the world's highest awards in electron paramagnetic resonance. In 2016, Collison participated in a research which reported the use of an organic donor–acceptor polymer containing a viologen electron acceptor and triarylamine electron donor as a platform in the development of multifunctional materials. The research explored the interplay between electronic and host–guest interactions in the synthesized polymers; POP-V1 containing a redox active triarylamine core and POP-V2 containing a redox inactive benzene core, in which the redox states present can be reversibly accessed.
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The living nature of NMP is due to the persistent radical effect (PRE).Bertin, D., et al. Chem. Soc. Rev., 2011, 40, 2189–2198 The PRE is a phenomenon observable in some radical systems which leads to the highly favored formation of one product to the near exclusion of other radical couplings due to one of the radical species being particularly stable, existing in greater and greater concentrations as the reaction progresses while the other one is transient, reacting quickly with either itself in a termination step or with the persistent radical to form a desired product. As time goes on, a higher concentration of the persistent radical is present, which couples reversibly with itself, meaning that any of the transient radical still present tends to couple with the persistent radical rather than itself due to greater availability.
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Myoglobin sketch Alpha helix 1960 - Myoglobin was the very first high-resolution crystal structure of a protein molecule. Myoglobin cradles an iron-containing heme group that reversibly binds oxygen for use in powering muscle fibers, and those first crystals were of myoglobin from the sperm whale, whose muscles need copious oxygen storage for deep dives. The myoglobin 3-dimensional structure is made up of 8 alpha-helices, and the crystal structure showed that their conformation was right-handed and very closely matched the geometry proposed by Linus Pauling, with 3.6 residues per turn and backbone hydrogen bonds from the peptide NH of one residue to the peptide CO of residue i+4. Myoglobin is a model system for many types of biophysical studies, especially involving the binding process of small ligands such as oxygen and carbon monoxide.
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When an excess of parahydrogen is used during hydrogenation reactions (instead of the normal mixture of orthohydrogen to parahydrogen of 3:1), the resultant product exhibits hyperpolarized signals in proton NMR spectra, an effect termed PHIP (Parahydrogen Induced Polarisation) or, equivalently, PASADENA (Parahydrogen And Synthesis Allow Dramatically Enhanced Nuclear Alignment; named for first recognition of the effect by Bowers and Weitekamp of Caltech), a phenomenon that has been used to study the mechanism of hydrogenation reactions. Signal amplification by reversible exchange (SABRE) is a technique to hyperpolarize samples without chemically modifying them. Compared to orthohydrogen or organic molecules, a much greater fraction of the hydrogen nuclei in parahydrogen align with an applied magnetic field. In SABRE, a metal center reversibly binds to both the test molecule and a parahydrogen molecule facilitating the target molecule to pick up the polarization of the parahydrogen.
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This reversible bonding with oxygen is why hemoglobin is so useful for transporting oxygen around the body. Oxygen binds in an "end-on bent" geometry where one oxygen atom binds to Fe and the other protrudes at an angle. When oxygen is not bound, a very weakly bonded water molecule fills the site, forming a distorted octahedron. Even though carbon dioxide is carried by hemoglobin, it does not compete with oxygen for the iron-binding positions but is bound to the amine groups of the protein chains attached to the heme groups. The iron ion may be either in the ferrous Fe2+ or in the ferric Fe3+ state, but ferrihemoglobin (methemoglobin) (Fe3+) cannot bind oxygen. In binding, oxygen temporarily and reversibly oxidizes (Fe2+) to (Fe3+) while oxygen temporarily turns into the superoxide ion, thus iron must exist in the +2 oxidation state to bind oxygen.
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Hepatocytes metabolize cholesterol to cholic acid and chenodeoxycholic acid. These lipid-soluble bile acids are conjugated (reversibly attached) mainly to glycine or taurine molecules to form water soluble primary conjugated bile acids, sometimes called "bile salts". These bile acids travel to the gall bladder during the interdigestive phase for storage and to the descending part of the duodenum via the common bile duct through the major duodenal papilla during digestion. 95% of the bile acids which are delivered to the duodenum will be recycled by the enterohepatic circulation. Due to the pH of the small intestine, most of the bile acids are ionized and mostly occur as their sodium salts which are then called “primary conjugated bile salts.” In the lower small intestine and colon, bacteria dehydroxylate some of the primary bile salts to form secondary conjugated bile salts (which are still water-soluble).
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D-lysine 5,6-aminomutase belongs to the isomerase family of enzymes, specifically intramolecular transferases, which transfers amino groups. Its systematic name is D-2,6-diaminohexanoate 5,6-aminomutase. Other names in common use include D-α-lysine mutase and adenosylcobalamin-dependent D-lysine 5,6-aminomutase, which can be abbreviated as 5,6-LAM. Mutase reaction of 5,6-LAM 5,6-LAM is capable of reversibly catalyzing the migration of an amino group from ε-carbon to δ-carbon in both D-lysine and L-β-lysine, and catalyzing the migration of hydrogen atoms from δ-carbon to ε-carbon at the same time. It demonstrates greatest catalytic activity in 20mM Tris•HCl at pH 9.0-9.2. In the early 1950s, 5,6-LAM was discovered in the amino-acid- fermenting bacteria Clostridium sticklandii, in which lysine undergoes degradation under anaerobic conditions to equimolar amounts of acetate and butyrate.
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This algorithm is performed on a Lewis structure (a diagram that shows all valence electrons). Oxidation state equals the charge of an atom after each of its heteronuclear bonds has been assigned to the more-electronegative partner of the bond (except when that partner is a reversibly bonded Lewis-acid ligand) and homonuclear bonds have been divided equally: :240px where each "—" represents an electron pair (either shared between two atoms or solely on one atom), and "OS" is the oxidation state as a numerical variable. After the electrons have been assigned according to the vertical red lines on the formula, the total number of valence electrons that now "belong" to each atom are subtracted from the number N of valence electrons of the neutral atom (such as 5 for nitrogen in group 15) to yield that atom's oxidation state. This example shows the importance of describing the bonding.
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Elemental iodine hence forms diatomic molecules with chemical formula I2, where two iodine atoms share a pair of electrons in order to each achieve a stable octet for themselves; at high temperatures, these diatomic molecules reversibly dissociate a pair of iodine atoms. Similarly, the iodide anion, I−, is the strongest reducing agent among the stable halogens, being the most easily oxidised back to diatomic I2.Greenwood and Earnshaw, pp. 800–4 (Astatine goes further, being indeed unstable as At− and readily oxidised to At0 or At+, although the existence of At2 is not settled.) The halogens darken in colour as the group is descended: fluorine is a very pale yellow gas, chlorine is greenish-yellow, and bromine is a reddish-brown volatile liquid. Iodine conforms to the prevailing trend, being a shiny black crystalline solid that melts at 114 °C and boils at 183 °C to form a violet gas.
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In this respect Tracktion is often compared to Ableton Live, although Live has two separate work areas (Session and Arrange) and does not have fully context sensitive non modal elements that automatically show or hide depending on the task as does Tracktion. However both are notable for the use of a more abstract visual style that does not attempt to visually replicate "real world" recording equipment or effects boxes. As well as the drag and drop based non modal interface and rack filters, other key innovations of Tracktion's, later to be followed by most other DAWs, were the development of "freeze", a way of reversibly converting a midi instrument track to audio to free up memory and cpu, and an inline midi editor that allowed midi to be edited in the track rather than in a separate window or dedicated editor. Tracktion was also the first DAW to adopt a fully vector- based, resizable interface.
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As a result, sublingual estradiol has been found to result in estradiol levels and a ratio of estradiol to estrone that are substantially higher than oral estradiol. Maximal circulating levels of estradiol are as much as 10-fold higher with sublingual administration than with oral administration, and the absolute bioavailability of estradiol is approximately 5-fold higher. On the other hand, levels of estradiol fall rapidly with sublingual administration, whereas they remain elevated for a prolonged period of time with oral administration. This is due to the large circulating pool of hormonally inert estrogen conjugates with long half-lives that is reversibly generated with oral estradiol during first-pass metabolism, which serves as a metabolism-resistant and long-lasting reservoir for continuous reconversion back into estradiol. It is also responsible for the differences in ratios between sublingual estradiol and oral estradiol in terms of maximal estradiol levels (10:1) achieved and absolute bioavailability (5:1).
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Vanadium(V) oxide is a catalyst in the contact process for producing sulfuric acid Vanadium compounds are used extensively as catalysts; Vanadium pentoxide V2O5, is used as a catalyst in manufacturing sulfuric acid by the contact process In this process sulfur dioxide () is oxidized to the trioxide (): In this redox reaction, sulfur is oxidized from +4 to +6, and vanadium is reduced from +5 to +4: :V2O5 \+ SO2 → 2 VO2 \+ SO3 The catalyst is regenerated by oxidation with air: :4 VO2 \+ O2 → 2 V2O5 Similar oxidations are used in the production of maleic anhydride: :C4H10 \+ 3.5 O2 → C4H2O3 \+ 4 H2O Phthalic anhydride and several other bulk organic compounds are produced similarly. These green chemistry processes convert inexpensive feedstocks to highly functionalized, versatile intermediates. Vanadium is an important component of mixed metal oxide catalysts used in the oxidation of propane and propylene to acrolein, acrylic acid or the ammoxidation of propylene to acrylonitrile. In service, the oxidation state of vanadium changes dynamically and reversibly with the oxygen and the steam content of the reacting feed mixture.
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Cyclic voltammetry data has shown that various [1,2-b] IFs, can reversibly accept two electrons with the first reduction occurring at -0.8 V. The parent dione has a first reduction potential of -1.19 V, and halogenated versions reduce around -0.6 V. The fully conjugated version, first postulated by Deuschel in the 1950s, is believed to be even better as an electron carrier when compared to the analogus fullerene. This is believed to be due to a low lying LUMO, which was calculated in the Haley Group at the University of Oregon and corroborated by the Tobe group via crystal structure analysis. Confirmation of these low lying LUMOs wis provided by a tips acetylene appended, on the methyl bridges and the center ring, fully conjugated [1,2-b] IF had a first reduction of -0.62 V. The improvement in reduction potential is linked to the fact that the addition of 2 electrons yields an aromatic molecule with increased stability. However, the addition of the steric bulk required to make the molecule stable, lead to a herringbone crystal packing which is not favorable for electron mobility through the crystal.
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