TABLE 1.

Analyses of pro-convertase complexes

All kinetic analyses were performed using a two-state conformational change model.

Analyte	Bound ligand	kon1	koff1	KD	kon2	koff2	Error
		m−1 s−1	s−1	m	s−1	s−1	χ2
Recombinant fBa	C3b	1.8 106	0.135	7.3 10−8	1.1 10−2	2.8 10−3	0.23
E446V	C3b	1.0 106	0.016	1.6 10−8	4.4 10−3	4.5 10−3	0.90
E207A	C3b	1.9 106	0.090	4.6 10−8	5.4 10−3	7.2 10−3	0.84
Recombinant fB	CVF	0.8 106	0.038	4.6 10−8	1.8 10−3	3.3 10−3	0.83
E446V	CVF	0.7 106	0.020	2.9 10−8	2.9 10−3	2.7 10−5	0.74
Plasma fB This investigation	C3b	7.9 104	0.111	1.4 10−6	4.7 10−3	6.2 10−3	2.9
Plasma fB (Ref. 10)	C3b	1.4 104	0.12	8.5 10−6	5.5 10−3	1.8 10−3	4.2
Plasma fB (Ref. 11)	C3b	2.9 104	0.11	3.8 10−6	1.1 10−2	2.6 10−3	2.9b
Plasma fD	C3bBc	1.9 105	0.11	5.6 10−7	7.6 10−3	1.0 10−2	2.3

^a The disparity in K_D between plasma fB and recombinant fB is due predominantly to the difference in their k_on1 values (K_D = k_off1/k_on1). This could be the result of differential glycosylation and/or greater homogeneity of the recombinant protein versus the plasma protein. Importantly, the conclusions of this study are critically dependent on k_off1 values, and the k_off1 values obtained for recombinant fB and plasma fB are in agreement and consistent with the published values (above). Thus, the differences in k_on1 between plasma fB and recombinant fB, while of note, do not affect the major findings of this study.

^b Error determined by alternative method.

^c C3bB(Mg²⁺) complex incorporating the factor B^{D254G, N260D, 233AAA} mutation.