Moderate pressure has no distinct impact on hydrophobic hydration of proteins

• Δcp is the heat capacity increment of any protein under denaturation.
• We studied the effect of pressure on Δcp using a high pressure calorimeter.
• Pressure has no impact on Δcp up to 178 MPa.
• There is no noticeable pressure effect on hydration of unfolded proteins.

The effect of high pressure on the change in the heat capacity (Δcp) of ribonuclease A and lysozyme upon denaturation has been studied using scanning microcalorimetry techniques. It has been shown that the pressure has no impact on Δcp up to 178 MPa, although appreciably varies the denaturation enthalpy. This result confirms the thermodynamic similarity of the denaturation process and the hydration degree of polypeptide chain in the denatured state at ambient and elevated pressure. Our findings are in conflict with some hypotheses concerning the high pressure effect on the structure stability of proteins.