Summary
Purified Vipera palestinae hemorrhagin (VPH) impairs thrombin formation, fibrinogen
clottability, FSF activity, platelet clot retracting activity, ADP- and connective
tissue-induced platelet aggregation and connective tissue - induced platelet ADP release.
The effects of VPH became manifest or increased in intensity on incubation with the
respective substrates prior to measurement of their activities. Inactivation of the
VPH protease by DFP resulted in complete abolishment of the first four and partial
inhibition of the last two of the above VPH activities.
Administration of VPH to guinea pigs caused widespread hemorrhages, associated with
moderate hypofibrinogenemia but normal platelet count, clotting time and clot retraction.
DFP-treated VPH caused hemorrhage without hypofibrinogenemia.