Serpine
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| Occurrence | ||
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Serpins are proteins that are found in all living things; in humans they make up about ten percent of plasma proteins . They are structurally similar proteins that can perform different functions. Originally discovered serpins are able, the enzyme activity of serine proteases to block ( serpin = Ser domestic P roteinase- In inhibitors), this property does not have many other serpins. The serpins include antitrypsin , antithrombin , ovalbumin , plasminogen activator inhibitor, and neuroserpine . Its main task is to regulate protease activity. The UniProt protein database has over 40 secured members of the Serpin family, over 80 sequences are known.
Structurally, all serpins are characterized by the presence of three β-sheets and nine α-helices , which together form a structure under tension. As a result, any proteolytic cleavage in this structure leads to the loss of the inhibitor property. Inhibitory serpins bind to proteases in the vicinity of the catalytic domain; the inhibitory effect results initially from steric hindrance . The serpin is then cut open by the protease - the tension released in the serpin leads to far-reaching changes in conformation and ultimately to the destruction of the protease. The inhibition is therefore irreversible .
The terms serpin and serine protease inhibitor are not synonymous, as there are many other inhibitors of serine proteinases outside of serpins, and serpins are also able to inhibit other proteases. The protease-inhibiting serpins are summarized in the MEROPS database in clan 'ID' (family 'I4') and form the most extensive class of protease inhibitors .
Individual evidence
- ↑ Gettins, P., PA Patston, M. Schapira: Structure and mechanism of action of serpins. Hematology / oncology clinics of North America, Vol. 6, No. 6, 1992, pp. 1393-1408, PMID 1452519 .
- ^ Silverman, Gary A. et al .: The serpins are an expanding superfamily of structurally similar but functionally diverse proteins evolution, mechanism of inhibition, novel functions, and a revised nomenclature. Journal of Biological Chemistry, Volume 276, No. 36, 2001, pp. 33293-33296, doi : 10.1074 / jbc.R100016200 .
- ^ RJ Epstein: Human molecular biology . an introduction to the molecular basis of health and disease. University Press, Cambridge 2003, ISBN 0-521-64481-X , pp. 26 .
- ↑ MEROPS: Entry on I4 family , accessed on May 23, 2013.