Figure 3.

Probability distribution of the excess chemical potential due to the interactions between the water molecule and the protein as calculated via the Gaussian approximation. Each panel refers to a different pair of thermophilic/mesophilic homologues. Data for the mesophiles are in green, data for the thermophiles are in orange.The average value $\langle {\mu }_{ex}^{pw}\rangle$ are indicated by the vertical lines. All averages are lower than the bulk estimate for ${\mu }_{ex}^{bulk}=-9kcal/mol$ reporting an average favourable internal hydration.