2-Amino-4-methylvaleric acid; the l-isomer is one of the amino acid s found in proteins; a nutritionally essential amino acid.
- l. aminopeptidase aminopeptidase (cytosol).
- l. dehydrogenase an enzyme that catalyzes the reaction of l-l., water, and NAD+ to produce NADH, ammonia, and 4-methyl-2-oxopentanoate; used in the treatment of certain tumors.
- l. zipper a structural motif found in a number of proteins ( e.g., some of the DNA-binding regulatory proteins) in which leucyl residues align along one edge of the helix and can interdigitate with a similar structure on another protein molecule. [Zipper, orig. a trademark for a fastening device with two rows of interlocking teeth]
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leu·cine 'lü-.sēn n a white crystalline essential amino acid C6H13NO2 obtained by the hydrolysis of most dietary proteins abbr. Leu
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n.
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leu·cine (Leu) (L) (looґsēn) [Gr. leukos white] an essential amino acid, 2-amino-4-methylpentanoic acid, necessary for optimal growth in infants and for nitrogen equilibrium in human adults. It is obtained by the digestion or hydrolytic cleavage of protein. See also table at amino acid. [USP] a preparation of leucine used as a dietary supplement.Medical dictionary. 2011.