FIGURE 4.

Fluorescence (F) measurements of prothrombinase assembly. Reaction mixtures containing 10 nm OG₄₈₈-FXa, 10 nm FVa, and 50 μm PCPS in assay buffer were titrated with increasing concentrations of rFX (•), rFXa^S195A (▪), or rFXa^I16L (▴) for panel A, or EGR-rFXa (□) or EGR-rFXa^I16L (▵) for panel B. Fluorescence intensity was measured at 25 °C. The lines are drawn following analysis to independent, non-interacting sites, and the fitted values are given in Table 2. The data are representative of two to three similar experiments.