A potent platelet aggregation inhibitor purified from Agkistrodon halys (mamushi) snake venom

By means of gel filtration on Sephadex G-75, DEAE-Sephadex A-50 column chromatography and three gel filtrations on Sephadex G-75, a potent platelet aggregation inhibitor was purified from Agkistrodon halys snake venom and shown to be a single peptide chain, as judged by SDS-polyacrylamide gel electrophoresis. The purified platelet aggregation inhibitor was an acidic protein with a molecular weight of 14,000 and possessed phospholipase A 2 activity. Its inhibitory activity on platelet aggregation was heat stable (at 96°C, 30 min) in an acidic medium (pH 5.5), while its phospholipase A enzymatic activity was heat labile under the same conditions. Its inhibitory activity on platelet aggregation induced by thrombin, sodium arachidonate, collagen or ionophore A-23187 was non-competitive and dose-dependent with a similar id 50 (∼ 11 μg/ml). It exerted its inhibitory action without pre-incubation with platelet suspension, however, its inhibitory effect could be moderately increased after longer incubation (30 min).