3 - Plasma Proteinase Inhibitors

Abstract

There are various plasma proteinase inhibitors. Proteinase activity is an integral part of development, inflammation, and phagocytosis. Proteinase inhibitors constitute 10% of the total weight of mammalian plasma proteins. The chapter discusses α1-antitrypsin. The inherited deficiencies of α1-antitrypsin results in the disease states. The α2-macroglobulin (α2M) is one of the most potent proteinase inhibitors, having the capacity of inhibiting other classes of proteinases. The α2-macroglobulin entraps a broad range of proteinases, with different substrate specificity and catalytic mechanisms. An important function of α2-macroglobulin is its capacity to bind all cytokines, thus serving as an important mechanism of modulating cytokine activity. The inter-α trypsin inhibitor (IαTI) migrates between the α1 and α2 globulins electrophoretically and is an inhibitor of trypsin, chymotrypsin, and elastase. Proteinases serve important roles in protecting the host against infection and in producing cellular and molecular changes in the developing organisms. Protease inhibitors protect against uncontrolled proteolytic activity that could become a potentially lethal threat to the organism.