serpin /ser′pin/ , any of a superfamily of inhibitors of serine endopeptidase (serine proteinase), found in plasma and tissue. All are similarly structured single-chain glycoproteins, although each one acts specifically on particular endopeptidases. Among their targets are serine proteinases involved in coagulation, complement activation, fibrinolysis, inflammation, and tissue remodeling. The serpins include alpha1-antitrypsin, antithrombin III, alpha2-antiplasmin, C1 inhibitor, and plasminogen activator inhibitor 1. Also called serine protease inhibitor, serine proteinase inhibitor.
