25] Human kallikrein and prekallikrein

Abstract

Publisher Summary Kallikreins are proteases that specifically liberate kinins from plasma a2-globulin substrates known as kininogens. In plasma, kallikrein exists in a precursor form known as prekallikrein. Kallikreins can be divided into two classes depending on the source from which the enzymes are isolated. This chapter centers on human plasma prekallikrein and kallikrein. The enzymic activity of kallikrein is measured by two methods. It also quantifies the rate of release of kinins as determined by bioassay or radioimmunoassay. Alternatively, the ability of kallikrein to hydrolyze synthetic basic amino acid esters can be assessed. It also elaborates on Kinin-Releasing Assay Bioassay, which utilizes the smooth muscle contractions elicited by bradykinin, released by the action of kallikrein on kininogen. It also elaborates on Esterolytic Assay, in which methanol released from N-a-toluenesulfonyl-L-arginine methyl ester (TAME) is quantitated by the modification of the method of Siegelman et al. The chapter details the purification procedure and physical properties of Kallikreins and lists the natural and synthetic inhibitors.