Effect of a proteinase inhibitor from the plasma of Bothrops jararaca on coagulant and myotoxic activities of Bothrops venoms.

A proteinase inhibitor purified from the plasma of Bothrops jararaca was tested for the neutralization of total blood clotting activity, prothrombin activating factor and thrombin-like activity of B. jararaca venom and also myotoxic activity of B. jararacussu venom. This inhibitor was also tested for neutralization of the lethality induced by the venom of B. jararaca and B. jararacussu. The inhibitor markedly reduced the total blood clotting activity (95%) and the prothrombin activating factor (98%), and partially decreased the thrombin-like activity of B. jararaca venom. The proteinase inhibitor failed to neutralize the myotoxic activity of B. jararacussu. Lethality induced by the venom of B. jararaca in mice was inhibited by the proteinase inhibitor, whereas the protection on B. jararacussu venom was only partial. These results show that the proteinase inhibitor purified from the plasma of B. jararaca inhibits different proteinases but not myotoxins of Bothrops venoms, and consequently neutralizes the toxic effect due to these proteins.