Serpin

Serpins are proteins that occur in all living things; in humans, they account for about ten percent of the plasma proteins. They are structurally similar proteins that can perform different functions. Originally discovered serpins are able to block the enzyme activity of serine proteases, however, this property does not have a lot of other serpins. The serpins are antitrypsin, antithrombin, ovalbumin, plasminogen activator inhibitor and neuroserpin. Your task is primarily the regulation of protease activity. The protein database UniProt has over 40 members backed the serpin family, about 80 sequences are known.

Structurally, all serpins are characterized by the presence of three β -sheets and nine α - helices, which together form a standing structure under stress. This means that any proteolytic cleavage leads to this structure, the loss of the inhibitory property. Inhibitory serpins bind to proteases in the neighborhood of the catalytic domain; the inhibitory effect is mainly determined by steric hindrance. In addition, the serpin is cut by the protease - the released tension in the serpin leads to extensive conformational changes and ultimately to the destruction of the protease. The inhibition is thus irreversible.

The terms serpin and serine protease inhibitor, are not synonymous because there are many other inhibitors of serine proteinases outside the serpins and serpins inhibit other proteases are capable of. The protease inhibitory serpins in the MEROPS database Clan 'ID' ( 'family' I4 ') combined to form the largest class of protease inhibitors.