The inhibition of crotalase, a thrombin-like snake venom enzyme, by several peptide chloromethyl ketone derivatives

Characterization of snake venom components acting on blood coagulation and platelet function

Snake venoms can affect blood coagulation and platelet function in various ways. The physicochemical properties and the mechanisms of actions of the snake venom components affecting blood coagulation and platelet function are discussed.

Action of crotalase, an enzyme with thrombin-like and kallikrein-like specificities, on tripeptide nitroanilide derivatives

Since crotalase has thrombin-like and kallikrein-like functional and structural properties, we compared the actions of crotalase, thrombin and plasma kallikrein on 13 tripeptide nitroanilide substrates. Initial rates of hydrolysis were determined at 27 degrees C, pH 8.3, and used to construct Lineweaver-Burk plots from which Km and Vmax were determined. The ratio of kcat/Km was taken as a measure of enzymatic specificity. Crotalase yielded kcat/Km values for the following nitroanilide substrates in descending order of magnitude: H-D-NLeu-CHA-Arg, H-D-Pro-HHT-Arg, Tos-Gly-Pro-Arg, H-D-PhGly-Phe-Arg, Cbo-Glu(BuO)-Gly-Arg, H-D-But-CHA-Lys, H-D-CHG-But-Arg, H-D-NLeu-HHT-Lys, H-D-HHT-Ala-Arg, Bz-Pro-Phe-Arg, Tos-Gly-Pro-Lys, MeS-Leu-Gly-Arg, MeO-CO-CHG-Gly-Arg. This pattern of specificity correlated only roughly with those of thrombin and kallikrein.