Table 2.

Results of Binding Analysis

targeting molecule	KD,Sips (nM)a	KD,low[Fab′] (nM) b	KD,Sat[Fab′] (nM) c	Bmax,Sips (nM) d	Bmax,scat (nM) e	af	valence g	valence h
mAb	19 ± 1	NA	NA	0.72 ± 0.13	0.72	1	-	-
Fab′	58 ± 4	NA	NA	0.72 ± 0.09	0.72	1	-	-
P-7Fab′1.4	85 ± 11	47	109	0.98 ± 0.04	1.01	0.99 ± 0.08	1.4	1.4
P-3Fab′1.5	86 ± 14	32	190	1.09 ± 0.05	1.14	0.78 ± 0.06	1.6	1.5
P-3Fab′2.9	182 ± 35	34	226	2.04 ± 0.01	2.01	0.81 ± 0.07	2.8	2.9
P-3Fab′3.2	115 ± 25	27	204	2.18 ± 0.10	2.21	0.93 ± 0.09	3.1	3.2
P-3Fab′8.9	439 ± 165	15	257	7.5 ± 1.10	6	0.78 ± 0.16	8.2	8.9

^aAffinity binding constant determined by a least-squares fit of binding isotherm data.

^bAffinity binding constant derived from the inverse slope of Scatchard curves at low concentrations of Fab′.

^cAffinity binding constant derived from the inverse slope of Scatchard curves at saturating concentrations of Fab′.

^dTheoretical limit of bound ligand determined by a least-squares fit of the single-site binding equation.

^eTheoretical limit of bound ligand determined by graphical extrapolation of Scatchard plots to the x-axis.

^fHeterogeneity factor determined by the Sips equation.

^gValence of conjugates determined with modified amino acid analysis.

^hValence of conjugates determined by the ratio of B_max of the conjugate over B_max of the Fab′