HISTIDINE

From Big Medical Encyclopedia

HISTIDINE (beta imidazolil - alpha lactamic acid, C 6 H 9 N 3 O 2 ) — heterocyclic amino acid with dominance of the main properties, contains almost in all proteins.

Constitutional formula:

Treats group hexone bases (see).

In blood and tissues of the person and animals, in vegetable organisms there is in composition of proteins, and also in a free look and in the form of some derivatives, a hl. obr. peptides — carnosine (see) and anserine (see). Contains in a blood plasma of the person apprx. 1,7 mg of % of G.; in quite large numbers (St. 100 mg a day) G. is allocated with urine (G.'s maintenance in blood and its allocation with urine raise at pregnancy). Though need of presence of G. for food of the person is not proved and it is carried to replaceable amino acids, it is not replaceable in food of rats, dogs, mice, hens and many other animals. Neurospora crassa and other mushrooms contains G.'s betaine — gertsinin and its thiol derivative ergotionein (see. Betaines ). These connections are found also in blood of the person and a number of animals, however they, apparently, are not synthesized in an animal organism and get to it with food.

Scheme of a closing stage of biosynthesis of a histidine.

It was for the first time received by A. Kossel in 1896 from a hydrolyzate of protamin of a sturgeon — sturin and the same year S. Hedin — from a hydrolyzate of casein. It can be received also from hydrolyzates of other proteins. Many G. contains a globin (a proteinaceous part of hemoglobin) thanks to what blood is a rich source for G.'s receiving.

Crystallizes in the form of colourless plates, we will well dissolve in water, it is bad — in alcohol, it is insoluble in ether and chloroform, t°pl 277 ° (with decomposition). The isoelectric point of G. is at pH 7,6. Natural L-histidine, [a] 20 D — 39,3, has slightly bitterish taste.

Gives biuret reaction (see). Along with the methods of a chromatography and an electrophoresis, general for all amino acids, are applied to quantitative and qualitative test of G. characteristic reaction with diazotized sulphanilic to - that (see. Diazo test ), as a result the cut is formed the connection painted in red color and reaction of bromination in alkaline condition with formation of blue-violet connection.

All stages of biosynthesis of G. are completely studied at bacteria and at mushrooms (see the scheme). On a closing stage of biosynthesis of G. the I stage is catalyzed imidazolglitserofosfat - dehydratase (KF 4. 2. 1. 19), the II stage — histidinolphosphate - aminotransferase (KF 2. 6. 1. 9), the III stage — gistidinolfosfatazy (KF 3. 1. 3. 15), the IV stage — gistidinoldegidrogenazy (KF 1. 1. 1. 23).

During the studying of synthesis of G. at Salmonella typhimurium it is established that all enzymes participating in G.'s synthesis are controlled by one gistidinovy operon which is in turn under control of a repressor.

G.'s biosynthesis is regulated as a feed-back by repression, and also by inhibition of the first enzyme of a chain of biosynthesis by an end product of enzymatic reactions, i.e.

G. V a human body and animal G. breaks up hl. obr. under the influence of enzyme a histidine — ammonia-lyase (histidases; KF 4. 3. 1. 3), contained in a liver and in skin, with eliminating of ammonia and education urocanic to - you. Under the influence of enzyme of an urokanaza urocanic to - that breaks up to glutaminic and ant to - t through modes of formation imidazolonpropionovy and N-formiminoglutaminovoy to - t. The histidase and an urokanaza in a blood plasma normal are not found, but appear at hepatitis (see) and other gepatopatologiya. Definition of activity of these enzymes serves as auxiliary diagnostic test at these diseases.

At psoriasis, eczema and neurodermatitis disturbance of exchange of G. is established (S. R. Mardashev, etc., 1972). At height of a disease observed considerable (by 4 — 9 times) decrease of the activity of a histidase. At psoriasis this decrease is proportional to reduction of contents urocanic to - you in skin of patients that, perhaps, leads to more active decarboxylation of G. (urocanic to - that oppresses a histidinedecarboxylase) with formation of the histamine promoting development of a dermatosis.

In tissues of mammals, hl. obr. the mucous membrane of a stomach, contains also a histidinedecarboxylase (KF 4. 1. 1. 22), the carbon dioxide which is chipping off from G., turning it into biologically active amine — a histamine (see). In a blood plasma and in L-histidine urine it is possible to determine by an enzymatic method, using for this purpose a histidine — ammonia-lyase. As a result of reaction it is formed urocanic to - that, in neutral and alkaline condition the maximum of absorption at the wavelength of 277 nanometers has edges.

At a histidinemia first of all absence a histidine — ammonia-lyase (histidases) is found that leads to increase in maintenance of G. in blood and to allocation with urine of significant amounts of G. and its derivatives: an imidazole pyroracemic, imidazolmolochny and imidazoluksusny to - t at absence in urine urocanic to - you.

A wedge, manifestations — see. Histidinemia .

Histidine as drug

Histidinum is issued in the form of a histidine of a hydrochloride (Histidini hydrochloridum; synonym: Cloristin, Gerulcin, Herulcin, Histifan, Laristin, Laristidin, Stellidin, Ulcostidine). Let's well dissolve in water. It is quickly soaked up at any way of introduction.

Increases secretory and motor function went a little. - kish. a path that is probably connected with education from G. of a histamine. Finds properties of an adaptogen: at high content in food reduces negative influence on animals of high temperature, the lowered atmospheric pressure, ionizing radiation; at the same time activity of the enzymes participating in G.

Primenyayut G. metabolism for treatment at hepatitises, hron, gastritises with a hyperoxemia at a peptic ulcer of a stomach and duodenum increases. Enter intramusculary on 5 ml 4% of solution daily. The course of treatment of 20 — 30 injections then appoint 5 — 6 injections each 2 — 3 months of G. improves health, a dream, eliminates a pain syndrome and the dispeptic phenomena; at a considerable part of patients regeneration of a mucous membrane of a stomach or scarring of an ulcer is observed. At parenchymatous hepatitis the similar course of treatment accelerates recovery, normalizes pigmento-, protrombinoobrazovatelny and synthetic functions of a liver quicker. Use in complex antirheumatic treatment. At patients with atherosclerosis of G. improves indicators of lipidic exchange. Drugs G. usually have no side effect. Occasionally there are quickly passing weakness, pallor, pains in an anticardium.

Form of release: ampoules on 5 ml of 4% of solution; keep in the place protected from light.

See also Amino acids , Proteins .


Bibliography Braunstein A. E. Biochemistry of amino-acid exchange, M., 1949, bibliogr.; A. D viewfinder. Use of a histidine at atherosclerosis, the Doctor, business, No. 7, page 129, 1964; Maister A. Biochemistry of amino acids, the lane with English, M., 1961; Mardashev G. P. Biochemical problems of medicine, page 109, M., 1975; Shelygina H. M. Influence of a histidine on indicators of vascular permeability at rheumatism, Kazansk. medical zhurn., No. 4, page 19, 1968; In go qui st H. P. a. T of u p i n J. S. Amino acid metabolism, Ann. Rev. Biochem., v. 35, p. 231, 1966, bibliogr.; Histidine, Meth. Enzymol., v. 17B, Sect. 1, p. 1, N. Y. — L., 1971; Meister A. Biochemistry of the amino acids, v. 1 — 2, N. Y. — L., 1965; Truff a-Bachi P. Cohen G. N. Amino acid metabolism, Ann. Bev. Biochem., v. 42, p. 113, 1973, bibliogr.

I. B. Zbareky; I. V. Komissarov (pharm.).

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