GLUTAMINE

From Big Medical Encyclopedia

GLUTAMINE (C 5 H 10 O 3 N 2 ) — monoamide glutaminic to - you; H 2 NCOCH 2 CH 2 CH(NH 2 ) COOH. Is a constant component of tissues of animals. The essential role in processes of a metabolism in an organism since it is a product of neutralization of ammonia (see belongs. Nitrogen metabolism ). Contains in proteins (especially protamins and histones) and in a free Look — in fabrics of plants, animals and in microorganisms. Most of all free G. contains in plants.

Especially contains in a brain much — 110 mg of %, a cardiac muscle — 200 mg of %, skeletal muscles — 50 — 100 mg of %. It is allocated with urine in a free look and in the form of pair connection — a fenilatsetilglutamin (at people and a chimpanzee).

In the nature it is extended by L (+) - isomer with [a] 23 D + 6,0. A structural isomer of L (+) - a glutamine is the water soluble isoglutamine — 1-monoamide-glutaminic to - you: HOOC•CH 2 • CH 2 • CH(NH 2 ) • CONH 2 .

Pier. weight (weight) of G. 146,15. Crystallizes from water alcohol in the form of needles (t ° pl 185 °), it is dissolved in water (3,6 g in 100 ml at 18 °) and in alcohol (0,46 g in 100 ml at 23 °); in solution during the heating (100 °, pH 6,5) G. turns in pyrrolidone carboxylic to - that. Its Isoelectric point is at pH 5,7.

Quantitatively G. is determined by a gain of ammonia after hydrolysis in 1 N solution H 2 SO 4 . Hydrolysis can be carried out also by means of enzyme of a glutaminase (KF 3.5.1.2.), especially active in kidneys where it possesses an essential role at hydrolysis of G. brought with blood with formation of ammonia which is emitted with urine. It is synthesized from glutaminic to - you and ammonia in various tissues of animals. From fabrics the glutaminsintetaza is allocated (KF 6.3.1.2.), G. catalyzing synthetic reaction from a L-glutamate, ATP and ammonia. Under action the glutamine - ketoacid aminotransferase (KF 2.6.1.15) G. reacts interaminations (see) with many alpha ketonic acids, forming the corresponding amino acids and gamma amide 2-keto-glutaric to - you which is easily aminated in glutaminic to - that. Participates also in the reactions of amide interchange leading to formation of glycine from glyoxylic to - you, asparagine — from asparaginic to - you, adenylic to - you — from inosinic to - you. The amide group G. serves as the donator of the 3rd and 9th nitrogen atoms in a ring of purines and NH 2 - groups guanylic to - you and a gaunina, and also NH 2 - groups glycosamine (see).

Takes part in biosynthesis of aminosugars, being an intermediate product in a chain of transformation of glyukozo-6-phosphate in uridinediphosphate-N-atsetilglyukozamin and N-atsetilmannozamin. In this case reaction of transfer of NH2 group catalyzes L - glutamine-fruktozo-@-phosphate — aminotransferase (KF 2.6.1.16).

A row patol, states at the person is followed by changes of maintenance of G. in blood and fabrics: G.'s concentration is reduced in blood at gout, a hypoxia, epilepsy, avitaminosis of B 6  ; in muscles — at atrophies after section of a motor nerve or a sinew; G.'s maintenance is increased in muscles at muscular dystrophy, intoxication by ammonia, hypoxias. In a gastric juice G.'s maintenance increases at an ulcer and a carcinoma of the stomach.

See also Amides , Glutamic acid .


Bibliography Kozlov E. A. and Kovalenko N. A. Glutaminases, in book: Usp. biol, chemical, under the editorship of B. N. Stepanenko, t. 13, page 49, M., 1972; Silakovaa. I. Ferment of disintegration of a glutamine glutaminase in functionally various muscles, in kN: Exchange of amino acids, under the editorship of P. A. Côme-tiani, page 122, Tbilisi, 1967, bibliogr.; T r u f f and-B and with h i P. Cohen G. N. Amino acid metabolism, Ann. Rev. Biochem., v. 42, p. 113, 1973, bibliogr.

A. I. Silakova.

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