TABLE 1.

Summary of thermodynamic data for the binding of sB7-1 and B7-2v to CTLA-4Fc

Temperature	Kda	ΔGcalcb	ΔHobsc	TΔScalcd	ne
°C	μm		kcal/mol
sB7-1/CTLA-4Fc
15	0.08	−9.33	−10.40 ± 0.08	−1.07	0.93
25	0.12	−9.41	−13.35 ± 0.06	−3.94	1.08
30	0.14	−9.48	−14.57 ± 0.06	−5.09	1.1
35	0.23	−9.37	−15.57 ± 0.09	−6.20	0.99
B7-2v/CTLA-4Fc
15	0.45	−8.36	−8.73 ± 0.08	−0.37	1.13
25	0.56	−8.52	−11.70 ± 0.09	−3.18	1.08
30	1.10	−8.26	−13.57 ± 0.11	−5.31	1.13
35	0.83	−8.57	−14.27 ± 0.14	−5.70	1.11

^a K_d = 1/K_a.

^b ΔG_calc = −RT × ln(K_a).

^c Errors for fits of ΔH_obs are shown, for titrations done 2–3 times each. The fitting errors on the K_d values are of the order of <10% of the values shown. All experiments have “C values” between 10 and 250.

^d TΔS_calc = ΔH_obs − ΔG_calc.

^e Stoichiometry calculated using [CTLA-4 monomer].