Identification of 50 kDa snake venom proteins which specifically inhibit platelet adhesion to collagen

Of 32 snake venoms tested, the crude venoms of four (B.atrox, B.jararaca, A.halys blomhoffi and C.basiliscus) showed strong inhibitory activity in an assay of platelet adhesion to collagen. Active 50 kDa proteins were purified to homogeneity from each venom and found to be rich in cysteine on amino acid analysis. A monoclonal antibody raised against the purified B. atrox protein crossreacted strongly with the 50 kDa proteins from B.jararaca and A.halys blomhoffi and weakly with the protein from C.basiliscus, indicating that all four proteins possess a similar epitope. The proteins inhibited platelet aggregation induced by collagen but not by other agonists.