A yellow coloration is developed upon exposure of santonin to light. Santonin is optically levorotatory.
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Levoamphetamine is the levorotatory stereoisomer of the amphetamine molecule. Racemic amphetamine contains two optical isomers, dextroamphetamine and levoamphetamine.
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Rather, it indicates the compound's stereochemistry relative to that of the dextrorotatory or levorotatory enantiomer of glyceraldehyde. The dextrorotatory isomer of glyceraldehyde is, in fact, the isomer. Nine of the nineteen -amino acids commonly found in proteins are dextrorotatory (at a wavelength of 589 nm), and -fructose is also referred to as levulose because it is levorotatory. A rule of thumb for determining the isomeric form of an amino acid is the "CORN" rule.
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Like tartaric acid, calcium tartrate has two asymmetric carbons, hence it has two chiral isomers and a non-chiral isomer (meso-form). Most calcium tartrate of biological origin is the chiral levorotatory (–) isomer.
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Sometimes the D\- and L\- stereodescriptors mentioned above are mistakenly confused with obsolete small capital italic d- and l- stereodescriptors, which are equivalent with dextrorotatory and levorotatory optical rotation, i.e. (+)- and (−)- stereodescriptors, respectively.
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Compounds that rotate a plane of polarized light counterclockwise are referred to as levorotatory and are preceded by a (-) sign.Bruice, P. Y. Organic Chemistry; Pearson Prentice Hall: Upper Saddle River, NJ, 2007; pp 212-213.
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The levorotatory enantiomer of ketoconazole, levoketoconazole, shows 12-fold reduced potency in inhibition of this enzyme, and is under development for certain indications (e.g., Cushing's syndrome) as a replacement for ketoconazole with reduced toxicity and improved tolerability and safety.
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Selegiline is the levorotatory enantiomer of the racemic mixture deprenyl. Selegiline is synthesized by the alkylation of (–)-methamphetamine using propargyl bromide.J. Knoll, E. Sanfai, (1966).J. Hermann Nee Voeroes, Z. Ecsery, G. Sabo, L. Arvai, L. Nagi, O. Orban, E. Sanfai, (1986)B.
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Eucalyptus laevopinea was first described in 1898 by Richard Thomas Baker in Proceedings of the Linnean Society of New South Wales. The specific epithet (laevopinea) is derived from the Latin laevo- meaning 'left' and pinene, an essential oil, referring to the levorotatory pinene.
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LevomethamphetamineOther names include l-methamphetamine, levodesoxyephedrine, l-desoxyephedrine, levmetamfetamine (INN and USAN). is the levorotatory (L-enantiomer) form of methamphetamine. Levomethamphetamine is a sympathomimetic vasoconstrictor which is the active ingredient in some over- the-counter (OTC) nasal decongestant inhalers in the United States.
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Sucrose rotates in polarimeter as dextroratatory-D whereas invert sugar is levorotatory-L. This made tracking the inversion of sugar relatively simple. They also found that α-D-glucose is released in reactions catalyzed by invertase which is very unstable and spontaneously changes to β-D-glucose.
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Levomilnacipran (brand name Fetzima) is an antidepressant which was approved in the United States in 2013 for the treatment of major depressive disorder (MDD) in adults. It is the levorotatory enantiomer of milnacipran, and has similar effects and pharmacology, acting as a serotonin–norepinephrine reuptake inhibitor (SNRI).
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Carbinoxamine is an antihistamine and anticholinergic agent. It is used for hay fever, vasomotor rhinitis, mild urticaria, angioedema, dermatographism and allergic conjunctivitis. Carbinoxamine is a histamine antagonist, specifically an H1-antagonist. The maleic acid salt of the levorotatory isomer is sold as the prescription drug rotoxamine.
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The dextrorotatory form, (+)-nicotine is physiologically less active than (−)-nicotine. (−)-nicotine is more toxic than (+)-nicotine. The salts of (+)-nicotine are usually dextrorotatory; this conversion between levorotatory and dextrorotatory upon protonation is common among alkaloids. The hydrochloride and sulfate salts become optically inactive if heated in a closed vessel above 180 °C.
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Rivalis Aplexa has a thin shell levorotatory, featuring a large oval opening with parietal callus lip sharp and wide. The tentacles are filiform and foot is very long in the back. Ovigerous masses are constituted by transparent oval eggs variable number embedded in a gelatinous mass.Martínez E, Rafael y Miranda A, Rafael E. 1968.
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Instead, there is axial chirality, which results from the handedness of the helicity itself. The clockwise and counterclockwise helices are non-superposable. By convention a left-handed helix is minus and labeled (M), a right-handed helix is plus and labeled (P). Evidence from CD spectroscopy suggests left-handed helices are levorotatory and right-handed helices are dextrorotatory.
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The original synthesis at Janssen Pharmaceutica resulted in the preparation of a racemic mixture of two enantiomers, whose hydrochloride salt was reported to have a melting point of 264–265 °C; the free base of the racemate has a melting point of 87–89 °C. The racemic mixture is referred to as "tetramisole" - levamisole refers only to the levorotatory enantiomer of tetramisole.
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An enantiomer can be named by the direction in which it rotates the plane of polarized light. Clockwise rotation of the light traveling toward the viewer is labeled (+) enantiomer. Its mirror-image is labeled (−). The (+) and (−) isomers have been also termed d- and l- (for dextrorotatory and levorotatory); But, naming with d- and l- is easy to confuse with - and - labeling and is therefore discouraged by IUPAC.
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The term optical activity is derived from the interaction of chiral materials with polarized light. In a solution, the (−)-form, or levorotatory form, of an optical isomer rotates the plane of a beam of linearly polarized light counterclockwise. The (+)-form, or dextrorotatory form, of an optical isomer does the opposite. The rotation of light is measured using a polarimeter and is expressed as the optical rotation.
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Bicalutamide is a racemic mixture consisting of equal proportions of enantiomers (R)-bicalutamide (dextrorotatory) and (S)-bicalutamide (levorotatory). Its systematic name () is (RS)-N-[4-cyano-3-(trifluoromethyl)phenyl]-3-[(4-fluorophenyl)sulfonyl]-2-hydroxy-2-methylpropanamide. The compound has a chemical formula of C18H14F4N2O4S, a molecular weight of 430.373 g/mol, and is a fine white to off-white powder. The acid dissociation constant (pKa') of bicalutamide is approximately 12.
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Levorphanol and its stereoisomer dextrorphan, the enantiomers of the racemic mixture racemorphan. Chemically, levorphanol belongs to the morphinan class and is (−)-3-hydroxy-N-methyl-morphinan. It is the "left-handed" (levorotatory) stereoisomer of racemorphan, that is the racemic mixture of the two stereoisomers with differing pharmacology. The "right-handed" (dextrorotatory) enantiomer of racemorphan is dextrorphan (DXO), an antitussive, potent dissociative hallucinogen (NMDA receptor antagonist), and weakly active opioid.
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Its flash point is 95 °C and its auto-ignition temperature is 244 °C. Nicotine is readily volatile (vapor pressure 5.5 ㎩ at 25 ℃) On exposure to ultraviolet light or various oxidizing agents, nicotine is converted to nicotine oxide, nicotinic acid (niacin, vitamin B3), and methylamine. Nicotine is optically active, having two enantiomeric forms. The naturally occurring form of nicotine is levorotatory with a specific rotation of [α]D=–166.4° ((−)-nicotine).
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Pasteur noticed that crystals of tartrates had small faces. Then he observed that, in racemic mixtures of tartrates, half of the crystals were right-handed and half were left-handed. In solution, the right-handed compound was dextrorotatory, and the left-handed one was levorotatory. Pasteur determined that optical activity related to the shape of the crystals, and that an asymmetric internal arrangement of the molecules of the compound was responsible for twisting the light.
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Tocotrienols extracted from plants are always dextrorotatory stereoisomers, signified as d-tocotrienols. In theory, levorotatory forms of tocotrienols (l-tocotrienols) could exist as well, which would have a 2S rather than 2R configuration at the molecules' single chiral center, but unlike synthetic dl-alpha-tocopherol, the marketed tocotrienol dietary supplements are all d-tocotrienol extracts from palm or annatto oils. Preliminary clinical trials on dietary supplement tocotrienols indicate potential for anti-disease activity.
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Levoamphetamine is a central nervous system (CNS) stimulant known to increase wakefulness and concentration in association with decreased appetite and fatigue. Pharmaceuticals that contain levoamphetamine are currently indicated and prescribed for the treatment of attention deficit hyperactivity disorder (ADHD), obesity, and narcolepsy in some countries. Levoamphetamine is the levorotatory stereoisomer of the amphetamine molecule. While pharmaceutical formulations containing enantiopure levoamphetamine are no longer manufactured, levomethamphetamine (levmetamfetamine) is still marketed and sold over-the-counter as a nasal decongestant.
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The first reported kinetic resolution was achieved by Louis Pasteur. After reacting aqueous racemic ammonium tartrate with a mold from Penicillium glaucum, he reisolated the remaining tartrate and found it was levorotatory. The chiral microorganisms present in the mold catalyzed the metabolization of (R,R)-tartrate selectively, leaving an excess of (S,S)-tartrate. Kinetic resolution by synthetic means was first reported by Marckwald and McKenzie in 1899 in the esterification of racemic mandelic acid with optically active (−)-menthol.
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Telbivudine is a synthetic thymidine β-L-nucleoside analogue; it is the L-isomer of thymidine. Telbivudine impairs hepatitis B virus (HBV) DNA replication by leading to chain termination. It differs from the natural nucleotide only with respect to the location of the sugar and base moieties, taking on an levorotatory configuration versus a dextrorotatory configuration as do the natural deoxynucleosides. It is taken orally in a dose of 600 mg once daily with or without food.
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Natto was known to be a sort of superfood which promoted health and longevity in Japan during the late 1800s. In 1881, Lippmann first discovered "lävulan" (levan) as the remaining gum from molasses produced in the sugar beet companies. Later on in 1901, Greig-Smith coined the name “levan” based on the levorotatory properties of this substance in polarized light. This polymer is made up of fructose, a monosaccharide sugar, connected in 2,6 beta glycosidic linkages.
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Whether in water or in the solid form, -(+)-glucose is dextrorotatory, meaning it will rotate the direction of polarized light clockwise as seen looking toward the light source. The effect is due to the chirality of the molecules, and indeed the mirror-image isomer, -(−)-glucose, is levorotatory (rotates polarized light counterclockwise) by the same amount. The strength of the effect is different for each of the five tautomers. Note that the - prefix does not refer directly to the optical properties of the compound.
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Levormeloxifene (; developmental code names 6720-CDRI, NNC-460020) is a selective estrogen receptor modulator (SERM) which was being developed as an alternative to estrogen replacement therapy for the treatment and prevention of postmenopausal bone loss but did not complete development and hence was never marketed. The development was stopped because of a high incidence of gynecological side effects during clinical trials. Levormeloxifene is the levorotatory enantiomer of ormeloxifene, which, in contrast, has been marketed, though rather as a hormonal contraceptive.
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Levofenfluramine (INN), or (−)-3-trifluoromethyl-N-ethylamphetamine, also known as (−)-fenfluramine or (R)-fenfluramine, is a drug of the amphetamine family that, itself (i.e., in enantiopure form), was never marketed. It is the levorotatory enantiomer of fenfluramine, the racemic form of the compound, whereas the dextrorotatory enantiomer is dexfenfluramine. Both fenfluramine and dexfenfluramine are anorectic agents that have been used clinically in the treatment of obesity (and hence, levofenfluramine has been as well since it is a component of fenfluramine).
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The physiological behavior of morphinans (naturally occurring and semi-synthetic derivatives) is thought to be associated with the aromatic A ring, the nitrogen-containing D ring and the "bridge" between these two rings formed by carbons 9, 10 and 11 of the core, with the D ring "above" the core (levorotatory). Small groups are usually found on morphinan derivatives at carbons 3 and 6. Many such derivatives have an epoxy group between carbons 4 and 5 (i.e., 4,5α-epoxy), thereby forming an E ring.
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In this system, compounds are named by analogy to glyceraldehyde, which, in general, produces unambiguous designations, but is easiest to see in the small biomolecules similar to glyceraldehyde. One example is the chiral amino acid alanine, which has two optical isomers, and they are labeled according to which isomer of glyceraldehyde they come from. On the other hand, glycine, the amino acid derived from glyceraldehyde, has no optical activity, as it is not chiral (achiral). The labeling is unrelated to (+)/(−); it does not indicate which enantiomer is dextrorotatory and which is levorotatory.
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Levonorgestrel, also known as 17α-ethynyl-18-methyl-19-nortestosterone or as 17α-ethynyl-18-methylestr-4-en-17β-ol-3-one, is a synthetic estrane steroid and a derivative of testosterone. It is the C13β or levorotatory stereoisomer and enantiopure form of norgestrel, the C13α or dextrorotatory isomer being inactive. Levonorgestrel is more specifically a derivative of norethisterone (17α-ethynyl-19-nortestosterone) and is the parent compound of the gonane (18-methylestrane) subgroup of the 19-nortestosterone family of progestins. Levonorgestrel acetate and levonorgestrel butanoate are C17β esters of levonorgestrel.
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The pharmacokinetics of zopiclone in humans are stereoselective. After oral administration of the racemic mixture, Cmax (time to maximum plasma concentration), area under the plasma time-concentration curve (AUC) and terminal elimination half-life values are higher for the dextrorotatory enantiomers, owing to the slower total clearance and smaller volume of distribution (corrected by the bioavailability), compared with the levorotatory enantiomer. In urine, the concentrations of the dextrorotatory enantiomers of the N-demethyl and N-oxide metabolites are higher than those of the respective antipodes. The pharmacokinetics of zopiclone are altered by aging and are influenced by renal and hepatic functions.
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Doisynolic acid is a synthetic, nonsteroidal, orally active estrogen that was never marketed. The reaction of estradiol or estrone with potassium hydroxide, a strong base, results in doisynolic acid as a degradation product, which retains high estrogenic activity, and this reaction was how the drug was discovered, in the late 1930s. The drug is a highly active and potent estrogen by the oral or subcutaneous route. The reaction of equilenin or dihydroequilenin with potassium hydroxide was also found to produce bisdehydrodoisynolic acid, the levorotatory isomer of which is an estrogen with an "astonishingly" high degree of potency, while the dextrorotatory isomer is inactive.
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Like many chiral molecules, the two stereoisomers of glyceraldehyde will gradually rotate the polarization direction of linearly polarized light as it passes through it, even in solution. The two stereoisomers are identified with the prefixes - and -, according to the sense of rotation: -glyceraldehyde is dextrorotatory (rotates the polarization axis clockwise), while -glyceraldehyde is levorotatory (rotates it counterclockwise). \- and -glucose The - and - prefixes are also used with other monosaccharides, to distinguish two particular stereoisomers that are mirror-images of each other. For this purpose, one considers the chiral carbon that is furthest removed from the C=O group.
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Levoketoconazole (, ) (developmental code name COR-003; tentative brand name Recorlev, previously NormoCort), also known as (2S,4R)-ketoconazole, is a steroidogenesis inhibitor that is under development by Strongbridge Biopharma (formerly Cortendo AB) for the treatment of Cushing's syndrome. It is currently in phase III clinical trials for this indication. The drug is the levorotatory or (2S,4R) enantiomer of ketoconazole. It is expected to have greater potency, efficacy, and safety, including a lower risk of hepatotoxicity, relative to racemic ketoconazole. Levoketoconazole is an inhibitor of the enzymes CYP11B1 (11β-hydroxylase), CYP17A1 (17α-hydroxylase/17,20-lyase), and CYP21A2 (21-hydroxylase).
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It indicates that the C-5 chiral center has the same handedness as that of -glyceraldehyde (which was so labeled because it is dextrorotatory). The fact that -glucose is dextrorotatory is a combined effect of its four chiral centers, not just of C-5; and indeed some of the other -aldohexoses are levorotatory. The conversion between the two anomers can be observed in a polarimeter, since pure α-glucose has a specific rotation angle of +112.2°·ml/(dm·g), pure β- D- glucose of +17.5°·ml/(dm·g).Manfred Hesse, Herbert Meier, Bernd Zeeh, Stefan Bienz, Laurent Bigler, Thomas Fox: Spektroskopische Methoden in der organischen Chemie.
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It does not have a Controlled Substances Act 1970 schedule, ACSCN, or annual aggregate manufacturing quota and may not necessarily be controlled, whilst norlevorphanol is; none of the dextrorotary derivatives of the dromoran and norlevorphanol sub-families of morphinan derivatives are controlled as they do not have opioid activity but the other racemic compounds are. 3-HM's levorotatory stereoisomer, norlevorphanol, in contrast to (+)-3-HM, is an opioid analgesic. It was never marketed as such however, probably due to a combination of the facts that norlevorphanol has low bioavailability and that its potency is diminished compared to its N-methylated analogue levorphanol. (+)-3-Hydroxymorphinan the Dextro isomer of 3-hydroxymorphinan.
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C2H2O4, m.p. 221–222 °C, and the tartrate (Sympatol), (C9H13NO2)2.C4H6O6, m.p. 188–190 °C.The Merck Index, 10th Ed. (1983), p. 1295, Merck & Co., Rahway, NJ. The presence of the hydroxy-group on the benzylic C of the synephrine molecule creates a chiral center, so the compound exists in the form of two enantiomers, d- and l- synephrine, or as the racemic mixture, d,l- synephrine. The dextrorotatory d-isomer corresponds to the (S)-configuration, and the levorotatory l-isomer to the (R)-configuration.J. M. Midgley, C. M. Thonoor, A. F. Drake, C. M. Williams, A. E. Koziol and G. J. Palenik (1989).
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Milnacipran inhibits the reuptake of serotonin and norepinephrine in an approximately 1:3 ratio, respectively. Milnacipran exerts no significant actions on H1, α1, D1, D2, and mACh receptors, nor on benzodiazepine and opioid binding sites. Recently, levomilnacipran, the levorotatory enantiomer of milnacipran, has been found to act as an inhibitor of beta-site amyloid precursor protein cleaving enzyme-1 (BACE-1), which is responsible for β-amyloid plaque formation, and hence may be a potentially useful drug in the treatment of Alzheimer's disease. Other BACE-1 inhibitors, such as CTS-21166 (ASP1720), MK-8931, and AZD3293 are currently in clinical trials for the treatment of Alzheimer's disease.
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The two asymmetric crystal forms, dextrorotatory and levorotatory, of tartaric acid. Sucrose solution concentration measuring experiment, demonstrating optical rotation. The rotation of the orientation of linearly polarized light was first observed in 1811 in quartz by French physicist François Jean Dominique Arago.Arago (1811) "Mémoire sur une modification remarquable qu'éprouvent les rayons lumineux dans leur passage à travers certains corps diaphanes et sur quelques autres nouveaux phénomènes d'optique" (Memoir on a remarkable modification that light rays experience during their passage through certain translucent substances and on some other new optical phenomena), Mémoires de la classe des sciences mathématiques et physiques de l'Institut Impérial de France, 1st part : 93–134.
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Fructose is even more strongly levorotatory than glucose is dextrorotatory. Invert sugar syrup, commercially formed by the hydrolysis of sucrose syrup to a mixture of the component simple sugars, fructose, and glucose, gets its name from the fact that the conversion causes the direction of rotation to "invert" from right to left. In 1849, Louis Pasteur resolved a problem concerning the nature of tartaric acid.Pasteur, L. (1850) "Recherches sur les propriétés spécifiques des deux acides qui composent l'acide racémique" (Researches on the specific properties of the two acids that compose the racemic acid), Annales de chimie et de physique, 3rd series, 28 : 56–99 ; see also appendix, pp. 99–117.
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Emsam transdermal patch, 6mg/24hr dose Deprenyl is a racemic compound a mixture of two isomers called enantiomers. Further work determined that the levorotatory enantiomer was a more potent MAO-inhibitor, which was published in 1967, and subsequent work was done with the single enantiomer L-deprenyl. In 1971, Knoll showed that selegiline selectively inhibits the B-isoform of monoamine oxidase (MAO-B) and proposed that it is unlikely to cause the infamous "cheese effect" (hypertensive crisis resulting from consuming foods containing tyramine) that occurs with non-selective MAO inhibitors. A few years later, two Parkinson's disease researchers based in Vienna, Peter Riederer and Walther Birkmayer, realized that selegiline could be useful in Parkinson's disease.
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Tocotrienols have only a single chiral center, which exists at the 2' chromanol ring carbon, at the point where the isoprenoid tail joins the ring. The other two corresponding centers in the phytyl tail of the corresponding tocopherols do not exist as chiral centers for tocotrienols due to unsaturation (C-C double bonds) at these sites. Tocotrienols extracted from plants are always dextrorotatory stereoisomers, signified as d-tocotrienols. In theory, (levorotatory; l-tocotrienol) forms of tocotrienols could exist as well, which would have a 2S rather than 2R configuration at the molecules' single chiral center, but unlike synthetic, dl-alpha-tocopherol, the marketed tocotrienol dietary supplements are all d-tocotrienol extracts from palm or annatto oils.
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They are also abundant components of the peptidoglycan cell walls of bacteria, and D-serine may act as a neurotransmitter in the brain. D-amino acids are used in racemic crystallography to create centrosymmetric crystals, which (depending on the protein) may allow for easier and more robust protein structure determination. The L and D convention for amino acid configuration refers not to the optical activity of the amino acid itself but rather to the optical activity of the isomer of glyceraldehyde from which that amino acid can, in theory, be synthesized (D-glyceraldehyde is dextrorotatory; L-glyceraldehyde is levorotatory). In alternative fashion, the (S) and (R) designators are used to indicate the absolute configuration.
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In 1840, Germain Hess proposed Hess's law, an early statement of the law of conservation of energy, which establishes that energy changes in a chemical process depend only on the states of the starting and product materials and not on the specific pathway taken between the two states. In 1847, Hermann Kolbe obtained acetic acid from completely inorganic sources, further disproving vitalism. In 1848, William Thomson, 1st Baron Kelvin (commonly known as Lord Kelvin) established the concept of absolute zero, the temperature at which all molecular motion ceases. In 1849, Louis Pasteur discovered that the racemic form of tartaric acid is a mixture of the levorotatory and dextrotatory forms, thus clarifying the nature of optical rotation and advancing the field of stereochemistry.
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The presence of multiple chiral features in a given compound increases the number of geometric forms possible, though there may still be some perfect-mirror-image pairs. A sample of a chemical is considered enantiopure (also termed enantiomerically pure) when it has, within the limits of detection, molecules of only one chirality. When present in a symmetric environment, enantiomers have identical chemical and physical properties except for their ability to rotate plane-polarized light (+/−) by equal amounts but in opposite directions (although the polarized light can be considered an asymmetric medium). Such compounds are therefore described as optically active, with specific terms for each enantiomer based on the direction: a dextrorotatory compound rotates light a clockwise (+) direction whereas a levorotatory compound rotates light in a counter-clockwise (–) direction.
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Cetirizine acts as a highly selective antagonist of the histamine H1 receptor. The Ki values for the H1 receptor are approximately 6 nM for cetirizine, 3 nM for levocetirizine, and 100 nM for dextrocetirizine, indicating that the levorotatory enantiomer is the main active form. Cetirizine has 600-fold or greater selectivity for the H1 receptor over a wide variety of other sites, including muscarinic acetylcholine, serotonin, dopamine, and α-adrenergic receptors, among many others. The drug shows 20,000-fold or greater selectivity for the H1 receptor over the five muscarinic acetylcholine receptors, and hence does not exhibit anticholinergic effects. It shows negligible inhibition of the hERG channel ( > 30 μM) and no cardiotoxicity has been observed with cetirizine at doses of up to 60 mg/day, six times the normal recommended dose and the highest dose of cetirizine that has been studied in healthy subjects.
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F-actin; surface representation of a repetition of 13 subunits based on Ken Holmes' actin filament model The classical description of F-actin states that it has a filamentous structure that can be considered to be a single stranded levorotatory helix with a rotation of 166° around the helical axis and an axial translation of 27.5 Å, or a single stranded dextrorotatory helix with a cross over spacing of 350–380 Å, with each actin surrounded by four more. The symmetry of the actin polymer at 2.17 subunits per turn of a helix is incompatible with the formation of crystals, which is only possible with a symmetry of exactly 2, 3, 4 or 6 subunits per turn. Therefore, models have to be constructed that explain these anomalies using data from electron microscopy, cryo-electron microscopy, crystallization of dimers in different positions and diffraction of X-rays. It should be pointed out that it is not correct to talk of a “structure” for a molecule as dynamic as the actin filament.
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