GLYCOSAMINE

From Big Medical Encyclopedia

GLYCOSAMINE (hitozamin; 2-amino-2-dezoksiglyukoza, C 6 H 13 O 5 N) — aminosugar, derivative glucose. Is a part of many polysaccharides which are contained in tissues of vertebrate animals and the person and is the main component of chitin — the structural polysaccharide forming an outside skeleton of insects and Crustacea.

In a molecule G. the OH group at the second carbon atom is replaced on amine (NH 2 ) group:

Has all properties of aminosugars. It represents quite strong basis and easily forms salts with acids. Muriatic G. well crystallizes. Also beta isomers G. are known alpha; [a] D for alpha and beta isomers of a D-glycosamine makes respectively + 100 ° and + 14 ° (in water). The final size of specific rotation of equilibrium mix alpha and beta isomers is equal +74 ° - +70 ° (in water). At G.'s crystallization crystals of an alpha form drop out of water solution.

Most often receive hydrolysis of chitin salt to - that. From a hydrolyzate allocate crystal muriatic

G. G. in fabrics of an animal organism and in bacteria it is formed from glyukozo-and fruktozo-6-phosphate and a L-glutamine. Reaction is catalyzed by глутамин-фруктозо-6-фосфат-аминотрансфераза enzyme (KF 2. 6. 1. 16). Formed D - glycosamine-@-phosphate under the influence of enzyme of a glyukozaminfosfatatsetiltransferaza (KF 2. 3. 1. 4) with participation atsetil-KOA glycosamine-6-phosphate turns into N-acetyl, i.e. its NH2 group is acetylated.

As a result of the reaction catalyzed by enzyme acetyl glyukozaminfosfomutazy (KF 2. 7. 5. 2), N-atsetilglyukozamin-@-phosphate turns into N-atsetilglyukozamin-1-phosphate. Inclusion of the last in a molecule of the corresponding polysaccharide happens through the transient formation N-acetyl uridinediphosphate of a glycosamine catalyzed by enzyme UDF-atsetilglyukozamin-epimerazoy (KF 5. 1. 3. 7). From famous derivative G. the greatest biol, matters N-atse-tilglyukozamin which is one of structural elements hyaluronic acids (see), heparin (see), carbohydrate component of group-specific polysaccharides of the person, animals and bacteria and so forth:

N - methyl - L - a glycosamine is a part of a molecule of streptomycin.

Determination of content of G. in blood serum is made usually as follows. After long hydrolysis (8 hours) of blood serum with salt to - that in the soldered ampoule the hydrolyzate is parted, neutralized alkali, added atsetilatseton and after heating in the boiling water bath flow alcohol and paradimethylbenzaldehyde. Fotometrirut at 530 nanometers, make calculation of maintenance of G. according to a standard curve.

Normal G.'s maintenance in blood serum of the person fluctuates within 61 — 78 mg of % (children have 52 — 69 mg of %).

Increase in concentration of G. in blood as well as other aminosugars, note at acute infections, collagenic diseases (see), cancer (see), to a lymphoma (see), at parenchymatous damage of a liver (see. Hepatitis , Cirrhoses of a liver ), at lymphogranulomatosis (see), approximately in half of cases of a diabetes mellitus.

See also Aminosugar .


Bibliography: Biochemical methods of a research in clinic, under the editorship of A. A. Pokrovsky, page 249, 592, M., 1969; Bull-calves S. M. and Kolesnikov and M. F. Definition of a glycosamine in mukoproteida and mucopolysaccharides, Biochemistry, t. 31, century 3, page 533, 1966, bibliogr.; Deglis.inikol-s about N of. Metabolic ways, the lane with English, page 147, M., 1973; GardellS. The analysis of mucopolysaccharides, in book: Biochem. of mucopolysaccharides of connective tissue, ed. by F. Clark a. J. K. Grant, p. 39, Cambridge, 1961, bibliogr.

S. M. Bychkov.

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