A kininogenase from bovine erythrocyte membranes has been purified 140-fold by affinity chromatography on pepstatin A-Agarose followed by ion exchange chromatography on CM Cellulose. The purified enzyme showed an apparent molecular weight of 31,000 daltons as measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its pH optimum is 7.5, and it was totally inhibited by soybean trypsin inhibitor, phenylmethyl-sulfonylfluoride, aprotinin, pepstatin, and dithiotreitol, suggesting the presence of a disulfide bond(s) whose integrity is(are) essential for maintaining the native three-dimensional structure. The referred enzyme was able to release kinin from a substrate partially purified from rat plasma. The kininogenase was activated by Zn2+, Ca2+, and cysteine-HCl.

Experiments were carried out in vivo by injecting Tityus serrulatus crude venom in rats followed by biological assays on the isolated guinea-pig ileum, to show the effects of scorpion venom on kallikrein-kinin system. Our results showed effects such as significant decrease of total kinin rate and a decrease of Zn , Na , Cl and K ions in rat urine 24 and 48 hours after the injection of Tityus serrulatus crude venom