Table 2.

Binding and kinetic constants for prothrombinase complex

	Factor Xa	Prothrombin
	K1/2Xa,pMa	Km,app, μMb	kcat,app, sec−1
2183A FVa	3.5 ± 1.4	0.11 ± .03	41 ± 2
2183A FVai	NDc	ND	ND
A2-SS-A3-FVa	8.0 ± 1.9	0.15 ± .01	38 ± 3
A2-SS-A3-FVai	549 ± 93	0.14 ± .01	4.1 ± 0.9
Q506-A2-SS-A3-FVa	6.1 ± 1.5	0.11 ± .01	42 ± 1
Q506-A2-SS-A3-FVai	47 ± 10	0.14 ± .01	31 ± 1
Q506/Q679-A2-SS-A3-FVa	9.5 ± 2.8	0.12 ± .03	43 ± 5
Q506/Q679-A2-SS-A3-FVai	53 ± 12	0.12 ± .03	39 ± 3

^a K_1/2Xa values (± S.E.) are averages of values calculated by fit to a standard hyperbolic curve of original data sets.

^b K_m,app and k_cat,app values (± S.E.) were similarly obtained.

^c ND = not detectable (≤2%).