Table 1.

Kinetics of peptidyl substrate cleavage

Shown are kinetic constants obtained from initial velocity studies conducted with varying concentrations of PF-3688 either in the absence or presence of different fixed concentrations of 4-aminobenzamidine. Each data set was composed of 11 different concentrations of PF-3668 (0–400 μm). Inhibition studies used four different concentrations of pAB fixed at 0, 75, 150, and 300 μm.

Enzymea	Inhibitor	Inhibition type	Vmaxb	Km	Ki
			ΔF/min	µm	µm
IXa	None	NAc	0.212 ± 0.006	267 ± 16	NA
IXa	None	NA	0.205 ± 0.008	213 ± 17	NA
IXa	pAB	Competitive	0.199 ± 0.008	200 ± 17	39 ± 2.2
IXa-VIIIa-PCPS	None	NA	0.369 ± 0.039	762 ± 111	NA
IXa-VIIIa-PCPS	None	NA	0.321 ± 0.031	652 ± 92	NA
IXa-VIIIa-PCPS	pAB	Competitive	0.343 ± 0.028	687 ± 79	111 ± 5
IXa-VIIIa-PCPS	pAB	Competitive	0.325 ± 0.021	669 ± 63	117 ± 5

^aStudies done with 75 nm IXa or with 75 nm IXa, 90 nm VIIIa, and 100 μm PCPS.

^bKinetic constants are reported ± 95% confidence limits.

^cNA, not applicable.