tryptophan

(trĭp`təfăn), organic compound, one of the 20 amino acidsamino acid
, any one of a class of simple organic compounds containing carbon, hydrogen, oxygen, nitrogen, and in certain cases sulfur. These compounds are the building blocks of proteins.
..... Click the link for more information. 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; human beings cannot synthesize it from simpler metabolites. Young adults require about 7 mg of this amino acid per day per kg (3 mg per lb) of body weight. Nicotinic acid (niacin), a vitaminvitamin,
group of organic substances that are required in the diet of humans and animals for normal growth, maintenance of life, and normal reproduction. Vitamins act as catalysts; very often either the vitamins themselves are coenzymes, or they form integral parts of coenzymes.
..... Click the link for more information. of the B complex, can be made from tryptophan in the body, but evidently the rate of transformation is insufficient for the demands of normal growth and maintenance, and hence nicotinic acid must be supplied in the diet. Deficiency of tryptophan in the diet enhances the progress of the vitamin-deficiency disease pellagrapellagra
, deficiency disease due to a lack of niacin (nicotinic acid), one of the components of the B complex vitamins in the diet. Niacin is plentiful in yeast, organ meats, peanuts, and wheat germ.
..... Click the link for more information. , which is treated by restoring nicotinic acid to the diet, usually supplemented with tryptophan. Bacteria in the intestine break tryptophan down to compounds such as skatole and indole, which to a great extent are responsible for the unpleasant odor of feces. Tryptophan contributes to the structure of proteins into which it has been incorporated by the tendency of its side chain to participate in hydrophobic interactions (see isoleucineisoleucine
, organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer appears in mammalian protein.
..... Click the link for more information. ). The amino acid was isolated from casein (milk protein) in 1901, and its structure was established in 1907.

Tryptophan

β-(β-indolyl)-α-aminopropionic acid, one of the most important natural amino acids. It exists in the form of optically active L- and D- forms and a racemic DL-form. L-tryptophan is a minor constituent of gamma globulins, fibrinogen, casein, and other proteins.

L-tryptophan is an essential amino acid. The daily requirements for adults and children up to seven years of age are 0.25 g and about 1 g, respectively. Tryptophan is synthesized in microorganisms and plants by condensation of the amino acid serine with indole, which is catalyzed by the enzyme tryptophan synthetase. (The biosynthesis of tryptophan in E. coli was used to demonstrate the collinearity of a gene and the polypeptide chain coded by that gene, in which the position of each amino acid in the polypeptide chain is determined by a special portion of the gene.) L-tryptophan undergoes complex transformations in animals, forming a number of essential compounds: its decomposition products are the basis for the formation of nicotinic acid and serotonin in humans and other mammals, eye pigments (ommo-chromes) in insects, and heteroauxins, indigo, and several alkaloids in plants. Skatole and indole are formed from tryptophan during putrefactive processes in the intestine. During the normal breakdown in the body, six of the 11 carbon atoms of tryptophan are included in the Krebs cycle through acetyl and acetoacetyl coenzyme A, and the other five are converted to CO₂.

In humans, the congenital absence of tryptophan pyrrolase, the enzyme that oxidizes tryptophan, results in feeblemindedness. Disruption of tryptophan metabolism in humans may be indicative of several serious diseases, including tuberculosis, cancer, and diabetes. Functional and organic disorders may also be caused by an insufficiency of tryptophan in the human diet and animal feed, resulting from the low content of tryptophan in many natural proteins. The food value of many proteins can be increased through the addition of synthetic tryptophan, obtained by chemical synthesis from acrylonitrile, ammonia, hydrogen cyanide, or phenylhydrazine. Techniques for enzymic synthesis of tryptophan from indole, pyruvic acid, and ammonia are under development.

REFERENCES

Braunshtein, A. E. Biokhimiia aminokislotnogo obmena. Moscow, 1949.
Lehninger, A. Biokhimiia. Moscow, 1974. (Translated from English.)
Meister, A. Biokhimiia aminokislot. Moscow, 1961. (Translated from English.)
Safonova, E. N., and V. M. Belikov. “Uspekhi v oblasti sinteza i proizvodstva a-aminokislot.” Uspekhi khimii, 1974, vol. 43, no. 9.

E. N. SAFONOVA

tryptophan

[′trip·tə‚fan] (biochemistry) C₁₁H₁₂O₂N₂ An amino acid obtained from casein, fibrin, and certain other proteins; it is a precursor of indoleacetic acid, serotonin, and nicotinic acid.

tryptophan

[trip´to-fan] a naturally occurring amino acid, one of the essential amino acids; it is a precursor of serotonin. Adequate levels in the diet may mitigate pellagra by compensating for deficiencies of niacin.

tryp·to·phan (Trp, W),

(trip'tō-fan), 2-Amino-3-(3-indolyl)propionic acid; the l-isomer is a component of proteins; a nutritionally essential amino acid.

tryptophan

(trĭp′tə-făn′) also

tryptophane

(-fān′)n. An essential amino acid, C₁₁H₁₂N₂O₂, formed from proteins during digestion by the action of proteolytic enzymes. It is necessary for normal growth and development and is the precursor of several substances, including serotonin and niacin.

tryptophan

An essential amino acid, which is a key building block in protein biosynthesis. It is a precursor for serotonin (a neurotransmitter) and niacin (a B vitamin).
Dietary sources
Milk, sesame seeds, soy beans, spirulina, sunflower seeds, cashews.

Fringe nutrition
Tryptophan has been promoted for its alleged ability to induce sleep, and as an antidepressint.

tryp·to·phan

(W) (trip'tŏ-fan) A nutritionally essential amino acid; the l-isomer is a component of proteins.

tryptophan

An antidepressant drug. L-tryptophan, sold in USA as a non-prescription food additive was withdrawn by the American Food and Drugs Administration (FDA) because of reports of a severe muscle disorder apparently caused by an unidentified contaminant. It is used only by hospital specialists who are aware of the risks. A brand name is Optimax.

Fig. 306 Tryptophan . Molecular structure.

tryptophan (W, Trp)

one of 20 AMINO ACIDS common in protein. It has a nonpolar ‘R’ group structure and is relatively insoluble in water. See Fig. 306 . The ISOELECTRIC POINT of tryptophan is 5.9.

Tryptophan

An essential amino acid that has to consumed in the diet because it cannot be manufactured by the body. Tryptophan is converted by the body to niacin, one of the B vitamins.Mentioned in: Hartnup Disease

tryp·to·phan

(Trp, W) (trip'tŏ-fan) A nutritionally essential amino acid.

tryptophan

tryp·to·phan

tryptophan

tryptophane

tryp•to•phan

also tryp•to•phane

tryp·to·phan

tryptophan

tryptophan

Tryptophan

REFERENCES

tryptophan

tryptophan

tryptophan

tryp·to·phan (Trp, W),

tryptophan

tryptophane

tryptophan

tryp·to·phan

tryptophan

tryptophan (W, Trp)

Tryptophan

tryp·to·phan

tryptophan

Synonyms for tryptophan

noun an amino acid that occurs in proteins

Synonyms

Related Words