A Bothrops jararaca plasma cysteine proteinase inhibitor related to Mammalian kininogen

ABSTRACT

A kininogen-like protein was purified from Bothrops jararaca plasma by DEAE-Sephadex ion-exchange and carboxy-methul-papain-Sepharose affinity chromatography. The molecular weight, estimated by SDS-gel electrophoresis, is about 100,000 and a species of about 75,000 is formed after incubation with hosrse urinary kallikrein. After incubation with rrypsin, only traces of biological activity were detected in tests on guinea pig ileum. The purified protein inhibits papain and bromelain, does not correct the clotting time of a kininogen-depleted human plasma, and does not affect the clotting time ogf plasma from Waglerophis merremii, a nonpoisonous snake; the same type of inhibitor was foind in this nonpoisonous snake. The dissociation cosntant (Ki) for the papain-inhibitor complex is approximately 1.6 nM