Fibrinogenolytic enzymes of Trimeresurus mucrosquamatus venom.

By means of CM-Sephadex C-50 column chromatography, Trimeresurus mucrosquamatus venom was separated into twenty fractions. The fibrinogenolytic activity was concentrated in Fractions 8, 10, 12, 13 and 14. Fractions 8 adn 13 had the highest ratio of fibrinogenolytic and caseinolytic activities. Fraction 8 possessed tosyl-L-arginine methyl esterase activity, while the others did not. The caseinolytic activities of Fractions 10, 12, 13 and 14 were inhibited by EDTA, while that of Fraction 8 was not. Fractions 8 and 13 were further purified by CM-cellulose and gel filtration and were homogeneous as judged by electrophoresis on polyacrylamide gel and cellulose acetate membrane. The molecular weights of the purified Fractions 8 and 13 were 26 000 and 22 400, respectively. Both were single peptide chains. The specific fibrinogenolytic activity of Fraction 8 was 17 mg fibrinogen/min/mg protein, while that of Fraction 13was 100 mg fibrinogen/min/mg protein. Fraction 13 digested specifically the alpha(A) chain of monomeric fibrinogen to yield two cleavage products. Fraction 8 digested the beta(B) chain first to yield four cleavage products. When the incubation time was prolonged, the alpha(A) chain was also partially digested by Fraction 8 to yield two cleavage products.