Valine

valine (văl`ēn), organic compound, one of the 22 α-amino acids commonly found in animal proteins. Only the l-stereoisomer appears in mammalian protein. It is one of several essential amino acids needed in the diet, as the human body cannot synthesize it from simpler metabolites. Young adults need about 23 mg of this amino acid per day per kilogram (10 mg per lb) of body weight. Valine can be degraded into simpler compounds by the enzymes of the body; an inherited defect in one of the enzymes involved in this process results in a rare disorder called maple syrup urine disease. Valine contributes to the structure of proteins into which it has been incorporated by the tendency of its side chain to participate in hydrophobic interactions. The structure of valine was established in 1906, after it had been first isolated from albumin in 1879. See isoleucine.

---

valine

One of the essential amino acids, found in most proteins. Produced industrially by hydrolysis of proteins or by chemical synthesis, it is used in biochemical and nutritional research and as a dietary supplement.

---

valine [′va‚lēn]

(biochemistry)

C₅H₁₁NO₂An amino acid considered essential for normal growth of animals, and biosynthesized from pyruvic acid.

---

Valine 

α-aminoisovaleric acid, (CH₃)₂,CHCH(NH₂)— COOH, one of the irreplaceable amino acids. Valine is included in proteins in the form of the L-isomer. The amount of valine in protein usually varies from 4.1 percent (horse myoglobin) to 7-8 percent (human serum albumen, milk casein) and sometimes 13-14 percent (connective-tissue elastin). The absence of valine from food makes it protein-deficient and results in a negative nitrogen balance.