Figure 4.

Comparison of binding enthalpies obtained by three different methods. The ΔH° value (gray bar) was calculated from a van’t Hoff plot using Eq. 11 and the ΔG° values in Table 2. The ΔH^vH values (black bars) were calculated from a van’t Hoff plot using the traditional free energy relationship, ΔG° = −RTlnK, and the K_i values obtained at a single starting concentration. The ΔH^ITC values (white bars) were obtained from the calorimeter output at 25 °C after subtracting the corresponding control run at each concentration; the ΔH^ITC values were weakly dependent on temperature and nearly constant with concentration (Table S1). The numbers on the graph above each pair of bars denote the starting concentrations of EDTA in mM.