Transient intermediates in the thrombin activation of fibrinogen. Evidence for only the desAA species

The structure of a fibrin gel depends on the nature of the fibrinogen activation products produced by thrombin and the physical condition under which assembly occurs. Two different structures of the intermediate fibrin protofibril have been proposed, the production of which requires different extents of fibrinopeptide A (FpA) cleavage from fibrinogen. The fibrin activation intermediates must be stable since time is required for the intermediates to diffuse to growing protofibrils. The classic Hall-Slayter model requires cleavage of both FpAs to form a desAA intermediate. The Hunziker model requires cleavage of only one FpA to form an AdesA intermediate. Electrophoretic quasi elastic light scattering has been used to show the time-dependent production of the relevant fibrinogen activation intermediates that includes desAA but not AdesA.