LECITHINASES

From Big Medical Encyclopedia

LECITHINASES — the outdated name of phospholipases, groups of the enzymes catalyzing hydrolytic decomposition of radio bonds in a molecule of letsitin and nek-ry other phosphoglycerides, napr, colamine - and serinephosphatides; products of fosfolipazny reaction possess toxic action on a human body and animals, most of them is hemolitic poisons.

Distinguish several types L. Phospholipase of A1 (lecithinase of A1, fosfatidat-1-acylhydrolase; KF3.1.1.32) hydrolyzes radio communication in a sopolozheniya of a molecule of lecithin (see. Letsitina ), therefore one molecule fat to - you is chipped off and formed beta atsilglitserilfosfokholip.

The lecithinase of A1 contains in many tissues and bodies of mammals (a liver, a spleen, lungs, a wall of a small bowel, testicular fabric, etc.).

Phospholipase of A2 (lecithinase of A2, phosphatide-2-atsilgidralaza; KF 3.1. 1.4), earlier called just by a lecithinase And, catalyzes hydrolytic eliminating fat to - you in the beta provision of a molecule of lecithin. The product which is formed at the same time carries the name lysolecithin. It possesses strong hemolitic action. The blood plasma of the person contains 5 — 12 mg of % of the lysolecithin connected with albumine and lipoproteids that levels its toxic action. At a sting of venomous snakes or spiders the content of lysolecithin in blood sharply increases, and the share of free lysolecithin increases. It leads to the fact that lizo lecithin communicates a membrane of erythrocytes, damaging it and causing hemolysis (see. Hemotoxins ). Haemo - and cytolytic effect of purulent exudates is connected with high content of a lecithinase of A2 in them (lysolecithins, etc.) and the lizofosfatid formed as a result of its action.

A lecithinase of A2 — the most well studied enzyme from group L. It is allocated in pure form from poison of snakes, bees and from tissue of a pancreas of animals. The lecithinase of A2 of juice of a pancreas comes to a gleam of a small bowel in an inactive form in the form of proferment and only after influence of the trypsin leading to eliminating from it of heptapeptide gains activity.

In an animal organism are constantly formed lizo letsitina, including and as a result of action of a lecithinase of A2 of fabrics on letsitina. However in many fabrics there are enzymes which are carrying out acylation and, thus, neutralization of the lysolecithins and beta atsilglitserilfosfokholinov formed at action of a lecithinase of A1. There is also alternative metabolic way, on Krom lysolecithin can be turned into lecithin: The 2nd lysolecithin —> lecithin + glitserilfosfokholin. Accumulation of lysolecithins can be prevented and if letsitina are at the same time affected by lecithinases of A1 and A2. An end product of their combined action is non-toxic for an organism glitserilfosfokholin. Transformation of lysolecithins in intestines goes such way at action of both L. juice of a pancreas.

A phospholipase In (a lecithinase In; lizofosfolipaza; lysolecithin-acylhydrolase; KF 3. 1. 1. 5) — the taken roots name of enzyme, to-ry actually is a complex of enzymes: lizoletsitinaza, lecithinases of A1 and A2. At action of this complex on lecithin or lysolecithin it is formed glycerophosphoric to - that and respectively two or one molecule fat to - you.

A phospholipase With (a lecithinase With, phosphatidylsincaline - cholinephosphohydrolase, KF 3. 1. 4. 3) catalyzes hydrolytic eliminating of phosphosincaline from a molecule of lecithin with education alpha, beta diacylglycerin. Enzyme was for the first time found in the toxin produced by Clostridium perfringens and later was identified as alpha toksinonim Toxic effect of enzyme at infection of wounds of Clostridium perfringens and is connected by other anaerobic microorganisms, apparently, with bystry destruction of the letsitin which are a part of cellular membranes. The lecithinase With is found also in tissues of animals: in a brain, a liver, kidneys, a spleen, etc.

Fosfolipaza D (a lecithinase of D; phosphatidylsincaline-fosfatidgidrolaza; KF 3.1.4.4) is found in plants. Enzyme splits radio communication between nitrogen base and the rest phosphoric to - you in a molecule of lecithin (serine - and a kolaminfosfatida) with formation of the free basis and fosfatidny to - you. Enzyme does not affect lysolecithin, glitserilfosfokholin or phosphosincaline. There are no convincing proofs of existence of a lecithinase in tissues of mammals.

Drugs of various L. are used in the pilot studies conducted in biochemical and medical - biochemical, laboratories (e.g., during the studying of cytochemistry of enzymes). The purified drugs of individual L. are issued for the scientific purposes.



Bibliography: Brokergof X. and Dyasensen R. Lipolytic enzymes (1974), the lane with English, page 243, M., 1978; Keyts M. Tekhnika of a lipidologiya, the lane with English, M., 1975; Lipids, ed. by R. Paolet-ti a. o., v. 1, N. Y., 1976; Lipids and lipidoses, ed. by G. Schettler, B., 1967.

A. H. Klimov.

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