ELASTASES

From Big Medical Encyclopedia

ELASTASES — peptide-hydrolase (KF 3.4.21...), differing in ability hydrolytic to split a molecule of elastin (fibrous connective tissue protein) which is a little giving in to effect of other proteinases. AA. selectively catalyze bond breaking, formed by carbonyl groups amino acids (see), having not loaded not aromatic side chains. Majority known E. is serinovy proteinases (see. Peptide-hydrolase ), however elastase macrophages (see), e.g., represents metalenzyme (see Metalloproteins). It is established that in the centers inflammations (see) from lysosomic granules (see. Lysosomes ) granulocytes are allocated E. and neutral proteinase. At genetically caused defect of alfa1-antitrypsin (see. Trypsin ) disintegration collagen (see) in the center of an inflammation under the influence of E. it is broken. AA. granulocytes and macrophages play an important role in destruction of connecting fabric at burns (see) and in a pathogeny of the diseases connected with destruction of elastic structures (see. Atherosclerosis , Emphysema of lungs).

Apparently, in exocrine (acinous) cells pancreas (see) not less than four are synthesized E. After the selection proteolytic eliminating of N-trailer alarm peptide E. in the form of inactive proferments (pro-elastases) with pancreatic juice get to a gleam of intestines where under the influence of trypsin turn into enzymes, from to-rykh the most active the pankreatopeptidaza E — elastase II (KF 3.4.21.11) is. Elastase is produced by also polymorphonuclear leukocytes (see). The peptides which are formed during the splitting elastin (see) under the influence of this elastase, differ from the peptides which are formed at hydrolysis of elastin under the influence of a pankreatopeptidaza E, Elastase of granulocytes is characterized by wider substrate specificity, than a pankreatopeptidaza To, and along with elastin splits collagen.

Special E. it is found in smooth muscle cells of a wall aortas (see), this E. works in a cell, regulating biosynthesis of elastin.

Together with E., synthesized by macrophages, especially the macrophages who are in the activated state and with E., allocated from thrombocytes (see), leukocytic E. generally defines elasto lytic activity of blood, edges naturally changes in the course of aging (see. Old age, aging ). It is established that at men elastolitichesky activity of blood increases during the period from the birth up to 25 years, and then progressively decreases, and at women after a maximum in 50 — 60 years elastolitichesky activity of blood sharply decreases.

Pier. weight (weight) of all E. makes 22 000 — 30 000, the optimum pH value is equal to 8,5.

Methods of definition E., based on use as substrate marked by isotopes or specific dyes of drugs of elastin, are complicated by presence at blood and fabrics of a row specific (alfa2-macroglobulin, alfa1-antitrypsin) and nonspecific (plasminogen, antithrombin) inhibitors E. Activity E. usually express in conventional units; in terms of the weight (weight) pancreatic E. elastolitichesky activity of blood of healthy people is equal to 63±35 mkg/ml.

See also Hydrolases , Enzymes .


Bibliography: Metsler D. Biochemistry, the lane with English, t. 2, page 108, m, 1980; The Nomenclature of enzymes, the lane with English, under the editorship of A. E. Braunstein, M., 1979: Hall D. A. The aging of connectivetissue, L. a. o., 1976; Werb Z. o. Elastases and elastin degradation, J. invest. Derm., v. 79, suppl. 1, p. 154, 1982.

L. I. Slutsky.

Яндекс.Метрика