TABLE 1.

Kinetics and dissociation constants for the interaction between human and pneumococcal GAPDHs and C1q or its isolated GR

Soluble analyte, GAPDHa	Immobilized ligand
	C1q	GR
Pneumococcal
KD (m)	0.34 × 10−9 ± 0.04 × 10−9	0.73 × 10−9 ± 0.21 × 10−9
χ2	0.59 ± 0.28	0.33 ± 0.15
ka (1/m s)	6.51 × 105 ± 4.42 × 104	7.92 × 105 ± 1.32 × 104
kd (1/s)	2.23 × 10−4 ± 4.29 × 10−5	5.47 × 10−4 ± 8.62 × 10−5
Human
KD (m)	2.17 × 10−9 ± 0.14 × 10−9	4.40 × 10−9 ± 1.32 × 10−9
χ2	1.48 ± 0.19	0.79 ± 0.01
ka (1/m s)	3.16 × 105 ± 3.42 × 104	3.22 × 105 ± 9.29 × 104
kd (1/s)	6.80 × 10−4 ± 2.67 × 10−5	1.25 × 10−3 ± 2.22 × 10−5

^a Binding of pneumococcal (1–10 nm) and human (5–50 nm) GAPDH was measured as described under “Experimental Procedures.” The association (k_a) and dissociation (k_d) rate constants were determined using a 1:1 Langmuir binding model. The values shown are the means of at least three separate experiments ±S.D.