Title: Methionine
CAS Registry Number: 63-68-3
CAS Name: L-Methionine
Additional Names: Met; M; 2-amino-4-(methylthio)butyric acid; a-amino-g-methylmercaptobutyric acid; (S)-2-amino-4-(methylthio)butanoic acid; g-methylthio-a-aminobutyric acid
Trademarks: Acimethin (Gry)
Molecular Formula: C5H11NO2S
Molecular Weight: 149.21
Percent Composition: C 40.25%, H 7.43%, N 9.39%, O 21.45%, S 21.49%
Literature References: Essential amino acid for human development. Universal translation start signal although usually missing from mature protein. Isoln from casein: J. H. Mueller, Proc. Soc. Exp. Biol. Med. 19, 161 (1922). Early chemistry and biochemistry: Amino Acids and Proteins, D. M. Greenberg, Ed. (Charles C. Thomas, Springfield, IL, 1951) 950 pp., passim; J. P. Greenstein, M. Winitz, Chemistry of the Amino Acids vols. 1-3 (John Wiley and Sons, Inc., New York, 1961) pp. 2125-2155, passim. Determn and distribution in non-protein fractions: J. Giovanelli, S. H. Mudd, J. Biochem. Biophys. Methods 11, 1 (1985). GC-MS determn in biological fluids: S. P. Stabler et al., Anal. Biochem. 162, 185 (1987). Evaluation as tracer in cancer imaging in mice: R. Kubota, J. Nucl. Med. 36, 484 (1995). Clinical evaluation in acetaminophen overdose: A. N. Hamlyn et al., J. Int. Med. Res. 9, 226 (1981). Clinical use as radiolabel in hyperparathyroidism: P. Hellman et al., Surgery 116, 974 (1994). Review of metabolism and clinical significance in man: L. D. Fleisher, G. E. Gaull, Clin. Endocrinol. Metab. 3, 37-55 (1974); and in carcinogenesis: T. L. Gatton-Umphress, Hosp. Pract. 28, 83-90 (1993). Review of toxicity: N. J. Benevenga, J. Agric. Food Chem. 22, 2-9 (1974). Review of biosynthesis: I. G. Old et al., Prog. Biophys. Mol. Biol. 56, 145-185 (1991). Review as translation start signal: T. Meinnel et al., Biochimie 75, 1061-1075 (1993).
Properties: Minute hexagonal plates from dil alc, mp 280-282° (dec, sealed capillary). [a]D25 -8.11° (c = 0.8). [a]D20 +23.40° (c = 5.0 in 3N HCl). Sol in water, but the crystals are somewhat water-repellent at first. Sol in warm, dil alcohol. Insol in abs alcohol, ether, petr ether, benzene, acetone.
Melting point: mp 280-282° (dec, sealed capillary)
Optical Rotation: [a]D25 -8.11° (c = 0.8); [a]D20 +23.40° (c = 5.0 in 3N HCl)
Derivative Type: D-Form
CAS Registry Number: 348-67-4
Literature References: Converted by deamination, followed by transamination with resultant inversion to the L-form. Comparative study with L-form of metabolism in plants: M. Pokorny et al., Phytochemistry 9, 2175 (1970). Evaluation in parenteral nutrition: K J. Printen et al., Am. J. Clin. Nutr. 32, 1200 (1979). Review: L. D. Stegink, D-Amino Acids in Clin. Nutr. Update: Amino Acids H. L. Greene et al., Eds. (American Medical Association, Chicago, IL, 1977) pp 198-206.
Properties: [a]D25 +8.12° (c = 0.8). [a]D25 -21.18° (c = 0.8 in 0.2N HCl).
Optical Rotation: [a]D25 +8.12° (c = 0.8); [a]D25 -21.18° (c = 0.8 in 0.2N HCl)
Derivative Type: DL-Form
CAS Registry Number: 59-51-8
Additional Names: Racemethionine
Trademarks: Banthionine (Banyu); Dyprin (Lincoln); Lobamine (Lobica); Metione (Lobica); Pedameth (Forest); Urimeth (North Am. Pharm.)
Properties: Platelets from alc, mp 281° (decompn). d 1.340. pK1 2.28; pK2 9.21. pH of 1% aq soln 5.6-6.1. Rf value 0.77. Soly in water (g/l) at 0°: 18.18; at 25°: 33.81; at 50°: 60.70; at 75°: 105.2; at 100°: 176.0. Sol in dil acids, alkalies. Very slightly sol in 95% alcohol. Insol in ether.
Melting point: mp 281° (decompn)
pKa: pK1 2.28; pK2 9.21
Density: d 1.340
Therap-Cat: Hepatoprotectant; antidote (acetaminophen poisoning); urinary acidifier.
Therap-Cat-Vet: Nutritional supplement; urinary acidifier.
Keywords: Antidote (Acetaminophen Poisoning); Hepatoprotectant; Acidifier.

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