Species difference in the fibrinogenolytic effects of alpha- and beta-fibrinogenases from Trimeresurus mucrosquamatus snake venom.

Alpha- and beta-fibrinogenases prepared from Trimeresurus mucrosquamatus venom digested specifically the alpha(A) and beta(B) chains of the fibrinogen molecule, respectively. alpha-Fibrinogenase digested bovine fibrinogen more markedly than human fibrinogen, while beta-fibrinogenase digested human fibrinogen more markedly than bovine fibrinogen. Human fibrin was also digested by both enzymes. Plasma fibrinogens of 4 animal species were digested by alpha-fibrinogenase to the same degree, while those by beta-fibrinogenase in the following order: human greater than dog greater than guinea-pig greater than rabbit. The fibrinogenolytic effects of alpha-fibrinogenase on human fibrinogen were strongly inhibited by sera of the 4 animal species, while those of beta-fibrinogenase were inhibited in the following order: rabbit greater than guinea-pig greater than dog greater than human. It was concluded that the different activities of the protease inhibitors in the plasma of animal species are mainly responsible for the sensitivity differences.