/me thuy"euh neen', -nin/, n. Biochem.an amino acid, CH3SCH2CH2CH(NH2)COOH, found in casein, wool, and other proteins or prepared synthetically: used as a supplement to a special diet in the prevention and treatment of certain liver diseases. Abbr.: Met; Symbol: M[1925-30; b. METHYL and THIONINE]
* * *It is used in pharmaceuticals, in enriched foods, and as a nutritional supplement and feed additive.
* * *sulfur-containing amino acid obtained by the hydrolysis of most common proteins. First isolated from casein (1922), methionine accounts for about 5 percent of the weight of egg albumin; other proteins contain much smaller amounts of methionine. It is one of several so-called essential amino acids for mammals and fowl; i.e., they cannot synthesize it. In microorganisms it is synthesized from the amino acids cysteine and aspartic acid.Methionine is important in methylation (the process by which methyl, or -CH3, groups are added to compounds) and is also a precursor of two other amino acids, cystine and cysteine.
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