ENTHALPY CONVERGENCE TEMPERATURES - PROTEINS AND MODEL COMPOUNDS

It is suggested that the classical model of non-polar hydration in proteins does not take into account a large negative enthalpy due to the solvation of polar surface, mostly represented by the peptide group. Analysis of the dissolution thermodynamics of several organic compounds, containing functional groups typical of proteins, clarifies that the penalty associated with the burial of polar surface in proteins shifts the temperature at which the water transfer enthalpy of non-polar moieties goes to zero, from room temperature to approx. 376 K. This seems to be the clue for reconciling opposing views on the role played by non-polar hydration in proteins.