The kallikrein, kininase and related peptides activities in central Asian snake venoms

The quantitative content estimation of kininogenases, kininases and related peptides have been made for Central Asian snake venoms: V. lebetina turanica and E. multisquamatus (gen. Vipera and Echis, fam. Viperidae), Ag. halys halys (gen. Agkistrodon, fam. Crotalidae) and N. oxiana (gen. Naja, fam Elapidae). It has been demonstrated, that all venoms investigated cause the contractile effect, when acting on isolated smooth muscle preparations. Kinin-like contractile activity was found in the low molecular weight fraction of the cobra venom. This action has the prolonged character as compared with bradykinin, but apart from it, results in the inactivation of the rat uterus because of cytotoxic components presence. The specific bradykinin-potentiating effect of the low molecular weight fraction of the E. multisquamatus venom has been discovered. It has been found, that the effect is connected with inhibition of the kininase II (angiotensin I converting enzyme, ACE). Two peptide inhibitors was isolated and characterized from this fraction.