Enthalpy–entropy compensation and determination of ΔC_p. The binding free energy change ΔG, ΔH, and entropy change −TΔS at each temperature presented in Table 2 were individually fit into a linear function. The sign and value for each ΔC_p were obtained from ΔH versus temperature fit as indicated. (a) Melibiose binding to MelB_St in the main buffer (the apo MelB_St). (b) Na⁺ binding to the apo MelB_St. (c) Melibiose binding to MelB_St preequilibrated with NaCl at 100 mM (MelB_St/Na⁺ binary complex). (d) Na⁺ binding to MelB_St preequilibrated with 50 mM melibiose (MelB_St/melibiose complex).