Correlations between the enzymatic activities and the factors active on blood coagulation and platelet aggregation from the venom of Vipera aspis

Abstract

The relations existing between the factors active on platelet aggregation and blood clotting and the enzymatic activities from the venom of Vipera aspis have been studied during purification procedures combining ion-exchange chromatography and gel filtration. 1. 1. The inhibition of ADP-induced platelet aggregation by the venom was explained by different mechanisms and could be ascribed to several well-defined enzymatic activities. A component displaying ADPase/5′ nucleotidase activity was the most potent inhibitor of aggregation. The fibrinolytic enzyme of the venom also decreased aggregation as did a component showing phospholipase A2 activity. K +-dependent ATPase activity was able to restore platelet aggregation obtained by the ADPase/5′ nucleotidase. These two enzymes appear to interact with ADP receptors of the platelet membrane. The venom phosphodiesterase did not seem to interfere on platelet aggregation. 2. 2.A fibrinolytic enzyme hydrolysing fibrin, fibrinogen and casein was found to be responsible for the fibrinolytic (plasma-like) activity of the crude venom. This enzyme did not show other proteolytic activity and was inactive on all the amino acid derivatives tested. 3. 3. Procoagulant factors similar to those observed in Russell's viper venom were found in V. aspis venom. An activator specific for Factor V has been separated from the arginine and tyrosine esterases and from the phospholipases A2 of the venom. Component of high molecular weight exhibited a procoagulant activity similar to that of the Factor X activator of Russell's viper venom. The V. aspis Factor X activator did not display tyrosine esterase or arginine esterase activity and could not be related to other enzymatic activities. 4. 4. A clotting inhibitor, not detectable in the crude venom appeared after the removal of procoagulant factors. It inhibited coagulation by forming a complex with phospholipids. No enzymatic activity, especially phospholipase A2 activity could be detected in this inhibitor.