Table 3.

Thermodynamic parameters obtained for the VcCBP/(GlcNAc)_n (n = 2, 3, and 4) interactions by means of ITC.

		N	Ka (108 M−1)	ΔH° (kcal·mol−1)	− TΔS° (kcal·mol−1)	ΔG° (kcal·mol−1)
VcCBP	(GlcNAc)2	0.9 ± 0.0	4.08 ± 1.03	− 2.40 ± 0.03	− 6.45 ± 0.11	− 8.85 ± 0.14
VcCBP	(GlcNAc)3	1.1 ± 0.01	0.64 ± 0.14	2.02 ± 0.09	− 9.56 ± 0.03	− 7.54 ± 0.12
VcCBP	(GlcNAc)4	1.0 ± 0.05	1.70 ± 0.04	5.47 ± 0.19	− 13.8 ± 0.16	− 8.36 ± 0.02
VcCBP_R27A	(GlcNAc)3	0.7 ± 0.18	0.083 ± 0.061	0.92 ± 0.30	− 7.30 ± 0.55	− 6.38 ± 0.55

The individual ligands (1.0 mM) were titrated into the VcCBP or VcCBP_R27A solution (50 µM) in 20 mM Tris–HCl buffer, pH 8.0, in the sample cell (0.2028 mL). The experiments were performed at 25 °C using an iTC200 system (Microcal Northampton, MA, USA). Three repeated experiments were conducted to obtain individual sets of the thermodynamic parameters.