Table 1.

Comparison of DX-2507 Fab and IgG binding affinities to FcRn

	DX-2507 IgG			DX-2507 Fab
	ka	kd	KDapp	ka	kd	KDapp
	m−1 s−1	s−1	nm	m−1 s−1	s−1	nm
pH 7.5b
Averagec	1.42E + 05	2.78E-04	1.95	1.71E + 05	3.08E-04	1.81
S.D.c	2.00E + 03	5.00E-07	0.03	2.50E + 03	1.50E-06	0.04
pH 6.0
Average	2.10E + 05	2.92E-04	1.39	2.41E + 05	3.30E-04	1.37
S.D.	2.00E + 03	1.00E-06	0.01	4.00E + 03	1.50E-06	0.01
pH 5.5
Average	2.64E + 05	3.36E-04	1.28	2.93E + 05	3.87E-04	1.33
S.D.	6.00E + 03	2.00E-06	0.03	8.00E + 03	5.00E-07	0.04

^a Kinetic values K_D^app, k_a, and k_d were determined by fits to SPR sensorgrams like those shown in Fig. 1 (A and B).

^b pH was established by varying running and dilution buffers as follows: pH 7.5 = 20 mm HEPES, pH 7.5, 150 mm NaCl, and 0.005% surfactant P20 (HBS-P buffer); pH 6.0 = 20 mm HEPES, pH 7.5, 150 mm NaCl, and 0.005% surfactant P20; pH 5.5 = 20 mm acetate, pH 5.5, 150 mm NaCl, and 0.005% surfactant P20.

^c Average and S.D. values were calculated for at least two replicate data sets.