Isolation, characterization and amino acid sequence of echicetin beta subunit, a specific inhibitor of von Willebrand factor and thrombin interaction with glycoprotein Ib.

Echicetin is a dimeric protein isolated from the venom of Echis carinatus that is a potent inhibitor of von Willebrand Factor and thrombin binding to glycoprotein Ib. Here, we report isolation and amino acid sequence of the beta subunit of echicetin that contains 123 amino acids, including 7 cysteines, and shows similarity with amino acid sequences of botrocetin and Factor IXa/Xa binding protein. We provide evidence that biological activity of echicetin which resides in this beta subunit is relatively resistant to reduction of the molecule.