ALCOHOL DEHYDROGENASE

From Big Medical Encyclopedia

ALCOHOL DEHYDROGENASE — the group name of the enzymes catalyzing a reversible test of oxidation of primary alcohols in aldehydes. Reaction proceeds according to the following scheme:

Balance of reaction is strongly shifted to the left side.

And. are found in many animals and vegetable fabrics and in microorganisms. In a crystal look And. it is allocated for the first time from beer yeast by Negeleyn in 1937. In 1948. And. it was succeeded to allocate from a liver of a horse. Partially purified drugs are received from germs of wheat, from microorganisms, a liver of fishes and rats. And. is indutsibelny (adaptive) enzyme: in kidneys of rats to which diet within a month added alcohol, contents And. raised.

Coenzyme And. (see. Coenzymes ) nicotinamide adenine dinucleotide (NAD) is; the enzyme demanding for the action nikotinamidadeshshdnnukleotidfosfat (NADF) is found in plants. Recovered OVER communicates with And. stronger, than oxidized.

And. malospetsifichna concerning structure of substrates also affect a large number normal and branched aliphatic and aromatic (primary and secondary) alcohols (see), and also carbonyl compounds. However And. stereospetsifichna concerning hydrogen transfer as the alcohol which is taken away from a molecule, and - attached to a coenzyme. And. is sulphhydryl enzyme. The number of sulphhydryl groups (SH-group) depends on a look And. E.g., the maximum number of SH-group in alcohol dehydrogenase of yeast — 36, a liver — 28. Pier. the weight of alcohol dehydrogenase of yeast — 150000, a liver — 84000. The first consists of 4 subunits and has 4 active centers. The second — has 2 subunits and 2 active center independent from each other. Each of them incorporates molecule OVER and an ion of zinc; the last can be replaced on cadmium. Removal of an ion of metal is followed by loss of enzymatic activity. In structure of an active center And. the remains of a lysine and cysteine enter. a rn-optimum of alkogoldegidrogenazny reaction — apprx. 8,0. Isoelectric point And. yeast lies at rn 5,4, and a liver — at rn 6,8. According to data of a spektrofotometriya And. a liver it is characterized by the low content of aromatic amino acids.

Inhibitors A.: ions of heavy metals, p-hlormerkuribenzoat, au phenanthroline (his action competitively in relation to a coenzyme), dithizon, urea, thiourea, azides, cyanides, hydroxylamine (works on And. a liver competitively in relation to substrate), some antibiotics (e.g., streptomycin).

And. a liver it is quite easily denatured at highly acid and strongly alkaline values rn, and also during the heating. The coenzyme renders the stabilizing effect.

Activity And. determine spektrofotometrichesk by the increase in optical density caused by recovery OVER during the use as the oxidized substrate of alcohol.

And. participates in process of fermentation, providing formation of alcohol from acetaldehyde. In the course of exchange of fructose A. recovers the glyceraldehyde which is formed during the splitting of fruktozo-1-phosphate in glycerin (see. Carbohydrate metabolism ). And. play an important role in the biochemical processes which are the cornerstone of sight — releasing the energy used in anaerobic conditions (see. Eye , biochemistry; Sight ), and also in processes of oxidation of the alcohol getting to an organism.

And. finds practical application in forensic medicine as specific reagent for determination of content of alcohol in blood. It is used also as analytical reagent for quantitative definition OVER (oxidized and recovered) and as auxiliary enzyme at measurement of activity of some other enzymes.

And. in blood serum of the healthy person it is not found, however appears at dysfunction and injury of a liver. Especially much it is found at acute hepatitises. At the same time obturatsionny jaundice and cirrhosis are not followed by emergence And. in blood.

In a reparative stage of an acute hepatitis And. disappears from blood earlier than indicators are normalized aminotransferases (see).

See also Enzymes .


Bibliography: Dickson M. and Webb E. enzymes, the lane with English, M., 1966; Sund H. and. Theorell H. Alcohol dehydroge-nases in book: Enzymes, ed. by P. D. Boyer an o.,' V. 7, p. 25, N. Y. — L., 1963. bibliogr.


G. A. Kochetov. \

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