/trip"teuh fan'/, n. Biochem.an essential amino acid, (C8H6N)CH2CH(NH2)COOH, colorless, crystalline, and aromatic, released from proteins by tryptic digestion and a precursor of serotonin. Abbr: Trp; Symbol: WAlso, tryptophane /trip"teuh fayn'/.[1900-05; trypto- (irreg. comb. form repr. Gk triptós rubbed) + -PHAN(E)]
* * *One of the essential amino acids.It is a heterocyclic compound that is found in small amounts in most proteins. It plays an important role in the growth and development of infants and in the biosynthesis of serotonin and niacin (thus, deficiency of niacin or tryptophan can cause pellagra). Its occurrence in milk has been suggested as the reason that drinking milk before bedtime helps people sleep. It is used in medicine and nutrition research, in enriched foods, and as a dietary supplement.
* * *an amino acid that is nutritionally important and occurs in small amounts in proteins. It is an essential amino acid, meaning that humans and certain other animals cannot synthesize it and must obtain it from their diets. Infants require greater amounts of tryptophan than adults to ensure normal growth and development. Tryptophan is used by the body to manufacture several important substances, including the neurotransmitter serotonin and the vitamin niacin. Diets poor in tryptophan can lead to pellagra (q.v.), a disease resulting from niacin deficiency; however, this disease is now rare in developed countries. In 1901 the English biochemist Frederick G. Hopkins isolated tryptophan from casein, the major protein found in milk.
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