URONIC ACIDS

From Big Medical Encyclopedia

URONIC ACIDS - derivatives of monosaccharides, at to-rykh primary spirit group it is oxidized to carboxyl; are a part of many biopolymers playing an important biological role participate in processes of a detoxication of harmful substances in an organism, in a free look are found in blood and urine of the person where contents nek-ry of them serves as auxiliary diagnostic test at a number of diseases. Genetically caused disturbance of exchange nek-ry At. to. diseases Gurler is the reason of hereditary diseases of the person, napr (see Glikozidoza, t. 10, additional materials) and Sheye (see Sheye a disease), Gunter's syndrome (see Mu-kopolisakharidozy), etc.

Disturbance of exchange At. to. at the person leads to development of nek-ry forms of pentosurias (see). At. to. take part in exchange of bilious pigments (see), including bilirubin (see). Disturbance of synthesis bilirubi - on - a glucuronide (see Glucuronides) plays an essential role in a pathogeny of nek-ry forms of jaundices (see). Disturbances of exchange of acid glycoses-aminoglycanes at rheumatism (see) can be revealed by determination of content At. to. in biol. liquids. D-glucuronic to - that is an initial metabolite in biosynthesis of ascorbic acid (see) in the vegetable and animal organisms synthesizing this vitamin.

In the nature are eurysynusic At. to., to-rye are derivatives of hexoses (see eksurokovy acids) and are a part of hyaluronic acids (see), hondroitiiser-ny acids (see) and others mu to polysaccharides (see). At. to. are found also in immunospecific polysaccharides of bacteria (see Bacteria, t. 5, additional materials).

At. to. represent solid amorphous or crystal, rather high-melting substances, it is almost nonvolatile, not rastvorima in low-polar solvents. well rastvorima in water and high-polarity solvents. Chemical properties U. to. are defined by presence at them carboxyl, carbonyl and hydroxylic groups: they have the recovering properties and ability to mutarotation (see) in solutions, form glycosides (see), are capable to oxidation, formation of lactones (see), esters, hydrazones, osazones, etc. Under the influence of strong to - t (see Acids and the bases.), ions of heavy metals or during the heating to 250 ° there is a decarboxylation (see). At. to.; in the diluted solutions of caustic soda U. to. epimerizutsya (see the Isomerism). At recovery from At. to. are formed and ldonovy to - you, at oxidation — sugar to - you.

Receive At. to. acid or enzymic hydrolysis of natural polyuronides, oxidation of aldoses, recovery of lactones sugar to - t, at nek-ry reactions of building or shortening of a carbon chain, etc. Biosynthesis At. to. there is by enzymatic dehydrogenation a nucleotide-difosfatsakharov at presence OVER (see N ikotinamidadenindinukleo-tid) or an epimerization of others At. to.

For detection At. to. use methods of a chromatography (see) and an electrophoresis (see). Quantitative definition At. to. carry out on measurement of amount of the emitted C02 carbon dioxide during the heating At. to. with strong to-tami, and also by means of staining reactions At. to. with ortsiny, a carbazole, naphthoresorcin (Tollens's test), resorcin, au aminophenol, etc. For identification At. to. recover in the corresponding monosaccharides (see) or oxidize in sugar to - you.

Bibliography: Kochetkov N. K. and d river. Chemistry of carbohydrates, page 13, etc., M., 19*67; Stepanenko B., N. Carbohydrates, page 59, M., 1968. V. K. Gorodetsky.

Яндекс.Метрика