Figure 1.

Inhibition of peptidyl substrate cleavage by pAB. Initial velocities for the cleavage of PF-3688 were measured with 75 nm IXa (A) or 75 nm IXa, 90 nm VIIIa, and 100 μm PCPS (B) in the presence of 0 (open circles), 75 (filled circles), 150 (open triangles), or 300 μm (filled triangles) pAB. In both panels, the lines are drawn following analysis to the rate expression for competitive inhibition using the fitted constants K_m = 200 ± 17 μm, K_i = 39 ± 2.2 μm, and V = 0.199 ± 0.008 ΔF/min (A) or K_m = 687 ± 79 μm, K_i = 111 ± 5 μm, and V = 0.343 ± 0.028 ΔF/min (B).