Figure 4
From: Modeling of human factor Va inactivation by activated protein C
Effect of Factor Xa on Activated Protein C Inactivation of Factor Va. Empircal time courses of FVa inactivation measured by activity analysis (Panels A and B) or by monitoring proteolytic cleavages (Panel C) are presented along with corresponding simulated time courses. All data points are presented as averages ± S.D. of 4–6 experiments. (A,B) Empirical time courses of APC (0.5 nM – black circles; 2.0 nM – red circles) inactivation of preformed prothrombinase (200 pM FVa and 100 pM FXa). Corresponding simulated time courses for 0.5 nM (black) or 2.0 nM (red) APC are presented with three potential KD values for the formation of the prothrombinase complex (100 pM – dotted lines; 500 pM – dashed lines; 750 pM – solid line): in Panel A each equilibrium process was described using a kon (4.0 x 108 M-1 s-1) and adjusting the koff constant; in Panel B each equilibrium process was described using a kon (1.5 x 108 M-1 s-1) and adjusting the koff constant. (C) Empirical time course of 2.0 nM APC inactivation of preformed prothrombinase (20 nM FVa and 30 nM FXa*) anaylzed by Western blotting. FVaHC densitometric data are expressed as relative to its value at time 0 (red circles). Corresponding simulated time courses for 2.0 nM (red) APC are presented using three potential KD values for the formation of the prothrombinase complex with each equilibrium process described by using a kon (1.5 x 108 M-1 s-1) and adjusting the koff constant (100 pM – dotted lines; 500 pM – dashed lines; 750 pM – solid line).