Fibrinogenolytic properties of natrahagin (a proteinase from cobra venom) and its effect on human platelet aggregation.

AIM: To study the fibrinogenolytic properties of natrahagin and its effect on platelet aggregation.

METHOD: SDS-PAGE, fibrinogenolytic activity assay, platelet aggregation.

RESULTS

Upon incubation of fibrinogen with natrahagin at the ratio of 50:1 (w/w), A alpha-chains of fibrinogen were almost completely hydrolyzed in 5 min; however, at least 6 h was needed for the complete degradation of gamma-chains. Fibrinogenolytic activity of natrahagin was 0.349 +/- 0.044 g.min-1.g-1 as determined by its ability to reduce the clottable fibrinogen. On the other hand, natrahagin concentration-dependently inhibited platelet aggregation induced by ristocetin in platelet-rich plasma and thrombin (80 U.L-1) in washed platelets with IC50 (95% confidence limit) of 56 (40-79) and 3.3 (1.4-8.0) mg.L-1. No inhibitory effect was found on collagen- and ADP-induced platelet aggregation even when the dose of natrahagin reached 200 mg.L-1.

CONCLUSION

Natrahagin is an alpha, gamma-fibrinogenase with an inhibitory effect on platelet membrane glycoprotein Ib (GPIb)-dependent platelet aggregation.