Interaction of echicetin with a high affinity thrombin binding site on platelet glycoprotein GPIb.

ABSTRACT

Echicetin, a protein isolated from Echis carinatus snake venom, inhibited platelet aggregation and secretion induced by low concentrations of thrombin ( < 0.2 U/ml), by binding to platelet glycoprotein Ib (GPIb). The inhibition was not observed when the platelets were stimulated with higher concentrations of thrombin ( > 0.2 U/ml). Echicetin competed with thrombin for binding to the high affinity site on GPIb. Thrombin also inhibited 50% of the binding of 125I-echicetin to the platelets.