Progress curves of fibrinopeptide release. Thrombin-catalyzed release of fibrinopeptides from plasma fibrinogen, dashed lines, FpA (□) and FpB (○); and recombinant fibrinogen, dotted line, FpA (▪) and FpB (•), was monitored by HPLC. The data were fitted to first-order rate equations, assuming FpA is released before FpB, as described.9 24