alanine

alanine (ăl'unēn") [key], organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer participates in the biosynthesis of proteins (see stereochemistry). Its side chain is a nonpolar, hydrophobic methyl group. The low reactivity of the amino acid permits silk, a protein which contains some 30% alanine, to have a simple, elongated structure with few cross-links. This contributes to the desirable features of the fiber-strength, resistance to stretching, and flexibility. Alanine is not essential to the human diet, since it can be synthesized from other cellular metabolites. It was discovered in protein in 1875.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2007, Columbia University Press. All rights reserved.

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