An Overview of Proteinase Inhibitors

Abstract

Proteinase inhibitors are proteins in the body that regulate the catalytic activity of proteinases. They are important in a large variety of physiologic processes including coagulation, digestion, tumor metastasis and immunity. Proteinase inhibitors are categorized as either nonspecific proteinase inhibitors or class-specific proteinase inhibitors. Nonspecific proteinase inhibitors are comprised soley of the alpha macroglobulins, most notably alpha2-macroglobulin. Class-specific proteinase inhibitors are subcategorized as serine proteinase inhibitors, aspartic proteinase inhibitors, metalloproteinase inhibitors, and cysteine proteinase inhibitors. Each subcategory is made up of numerous inhibitors. As the roles of individual proteinase inhibitors are determined, the therapeutic use of natural and synthetic proteinase inhibitors is also being investigated. The purpose of this article is to review the history and classification of proteinase inhibitors and their relevance to veterinary medicine.

Two cysteine proteinase inhibitors from Arabidopsis thaliana, AtCYSa and AtCYSb, increasing the salt, drought, oxidation and cold tolerance

“…Plant PIs may also be involved in the response to several biotic and abiotic stresses (Huang et al 2007). PIs are classified into nonspecific and class-specific superfamilies and the latter is subcategorized into several families including serine-, aspartic-, metallo-, and cysteine-proteinase inhibitor (Hibbetts et al 1999). Cysteine proteinase inhibitors (cystatins) inactivate proteinases by trapping them in an irreversible, tight equimolar complex (Barrett et al 1998).…”

Characterization of a stress responsive proteinase inhibitor gene with positive effect in improving drought resistance in rice

“…PIs were classiWed into non-speciWc and class-speciWc superfamilies and the later was subcategorized into several families including serine proteinase inhibitor, aspartic proteinase inhibitor, metalloproteinase inhibitor, and cysteine proteinase inhibitor (Hibbetts et al 1999). Serine proteinase appears to be the largest family of proteinase and plant serine-proteinase inhibitors have been classiWed into several subfamilies including soybean (Kunitz)-, Bowman-birk-, potato I-, potato II-, squash-, barley-, cereal-, ragi A-and thaumatin-PR like inhibitors (Haq et al 2004).…”

Purification and characterization of α1-proteinase inhibitor and antithrombin III: major serpins of rainbow trout (Oncorhynchuss mykiss) and carp (Cyprinus carpio) blood plasma

“…Serpins inhibit serine proteinases by an irreversible suicide substratelike inhibitory mechanism, forming stable enzymeinhibitor complexes in a 1:1 molar ratio. Inhibitory serpins interact with their target proteinase by specific binding at a reactive peptide bond P1-P1 0 located within a reactive center loop structure, 30-40 amino acids from the carboxyl terminus of the inhibitor (Hibbets et al 1999;Irving et al 2000;Potempa et al 1994;Silverman et al 2001;Zhou et al 2001).…”