FIBRINOPEPTIDE-B AND AGGREGATION OF FIBRINOGEN

Removal of fibrinopeptide B from human fibrinogen by reaction with the procoagulant enzyme from copperhead snake venom below 25°C resulted in tight aggregation of the fibrinogen, which, in turn, progressively blocked a concomitant but sluggish release of fibrinopeptide A by the enzyme. When the clots obtained at < 25°C were warmed, they dissociated into soluble aggregates and monomers. Release of fibrinopeptide A then resumed, and a secondary coagulation followed. The aggregation induced by release of fibrinopeptide B itself involves a plasmin-susceptible segment located just distal to B in the Bβ chain of fibrinogen, a segment previously shown to be of little importance in the aggregation induced by release of fibrinopeptide A. Copyright © 1979 AAAS.