Thermodynamic parameters for the binding reactions as determined by ITCa.

aAll titrations were conducted in Mes and Mops buffers 10 mM (pH 7.0) at 25°C. bKD is the dissociation constant; cKD, for HPrbs dilution, is the self-dissociation constant. Typical relative errors are 15% for KD, 5% for ΔG0 and 10% for ΔH0, −TΔS and nH. Experiments were performed in duplicate. dΔH0 is the buffer independent enthalpy for the binding reaction; its value was determined by conducting experiments in Mes and Mops buffers, 10 mM (pH 7.0) at 25°C, and by using Eq 5. eΔG0 is the binding free energy at 25°C, determined as ΔG0 = RT ln KD. f−TΔS0 is the value of the entropic contribution of the binding reaction at 25°C, determined as −TΔS0 = ΔG0 – ΔH0. gnH is the number of exchanged protons, determined by conducting experiments in Mes and Mops buffers, 10 mM (pH 7.0) at 25°C, by using the Eq. 5.