Figure 5.

Reaction profiles for the activation of prothrombin by prothrombinase. Progress curves for products and reactants for the activation of prothrombin by prothrombinase assembled with factor Va^Wt (A) or factor Va^Δ680−709 (B) were obtained by quantitative scanning densitometry of gels shown in panels A and B of Figure 4, as described in . The graphs illustrate the disappearance of prothrombin (◼), the transient formation of meizothrombin (○), and the accumulation of the B chain of α-thrombin (●). There is a 3-fold difference in the x-axis between the two panels, because prothrombinase assembled with factor Va^Δ680−709 consumes prothrombin with an ∼3-fold slower rate than prothrombinase assembled with factor Va^Wt. The lines for the disappearance of prothrombin were drawn according to the equation of a one-phase exponential decay (for factor Va^Wt, R² = 0.985; and for factor Va^Δ680−709, R² = 0.968). The lines depicting the formation of meizothrombin and the accumulation of the B chain of α-thrombin were arbitrarily drawn. Additional data points extending to incubation for 1 h (shown in Figure 4) have been omitted for clarity.