Studies on a procoagulant fraction of southern copperhead snake venom: the preferential release of fibrinopeptide B.

Abstract

Abstract The venom of the southern copperhead snake ( Ancistrodon contortrix contortrix ) possesses procoagulant and fibrinolytic properties. A procoagulant fraction, separated by chromatography and gel filtration, clotted fibrinogen directly and possessed proteolytic, esterolytic, and amidase activities. In its action upon fibrinogen, the fraction released fibrinopeptide B at a much faster rate than fibrinopeptide A, the reverse of the effect of thrombin. Despite the rapid release of fibrinopeptide B, visible clotting did not take place until appreciable fibrinopeptide A was also removed. These experiments support the view that visible clotting depends upon the removal of fibrinopeptide A from the fibrinogen molecule, permitting aggregation of monomeric units.