Figure 2.

Simple illustration of our physical picture of thermal denaturation of proteins. The wild type (a) and two mutants, (b) and (c), are considered here. ΔS_VH is the water-entropy gain and ΔS_C is the conformational- entropy loss upon folding. T_m, N_r, and k_B are the denaturation temperature, number of residues, and Boltzmann constant, respectively. The subscripts, “a”, “b”, and “c”, denote the values for the wild type (a) and two mutants, (b) and (c), respectively. ΔS_VH does not necessarily change linearly with the temperature T. The three solid lines of ΔS_VH/(k_BN_r) are not necessarily parallel.