PROTEIN INHIBITORS SYNTHESISED BY MICROORGANISMS
Authors: O. V. Matseliukh, L. D. Varbanets
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In a review the literature data on protein inhibitors of peptidases synthesised by different types of microorganisms are systematized. It is shown that at the present time on the basis of amino acid sequence homology protein inhibitors are grouped into 77 families, 29 of which include inhibitors of microorganisms. The mechanism of inhibition of peptidases by proteins may be related to their catalytic mechanism of action or include unrelated blocking of the active site or its surroundings. The structural elements of the protein inhibitors are responsible for binding to the peptidases, mostly include the N- or C-terminal sequences, the unprotected polypeptide loops (chains), which are acting independently or in combination with other elements. The basic properties, structural features and, where it is established, the functions of the protein inhibitors of peptidases are considered. Since some of these proteins effectively inhibit such peptidases as subtilisin, chymotrypsin, pancreatic elastase, their practical use in the treatment of diseases such as emphysema, arthritis, pancreatitis, thrombosis, hypertension, muscular dystrophy, cancer. It is suggested that the role of a bacterial homologue of Escherichia coli alphaacroglobulin, which is a periplasmic protein, is to protect the periplasmic space from the action of bacteria own proteases. Based on the specific properties of alpha-2-macroglobulin to bind endopeptidases active molecules, they are used in biotechnology to isolate endopeptidases from crude biological preparations and titration of its active centers. Some free–living bacteria are able to synthesize protein inhibitors to protect from the effects of its own enzymes, while the presence of these proteins in pathogens may play a certain role both in the infectious process and in the protection of the host proteases.