FIGURE 4.
Kinetics of ProT activation. A, initial rates of thrombin generation divided by the total enzyme concentration (vobs/[E]o; nm thrombin per min per nm Eo) for 8.5 pm NotD (●) or 1 pm FXa (○), 20 nm FVa, and 30 μm PC/PS LUVs as a function of total ProT concentration ([ProT]o). B, initial rates of thrombin generation as in A for 50 pm NotD and 20 nm FVa as a function of total ProT concentration ([ProT]o). C, initial rates as in A of 1 μm ProTR271Q activation by 10 pm NotD (●) or 10 pm FXa (○) in the presence of 30 μm PC/PS LUVs as a function of total FVa concentration ([FVa]o). NotD analysis includes FVa concentrations from 0 to 2 nm. D, initial rates as in A of 1 μm native ProT activation by 50 pm NotD as a function of total FVa concentration ([FVa]o). NotD analysis includes FVa concentrations from 0 to 20 nm. Solid lines represent the nonlinear least squares fits of the quadratic binding equation. Reactions were performed and analyzed as described under “Experimental Procedures.”