Solvation of biomolecules in aqueous kosmotrope solutions - The energetics of the glycerol interaction with amino acids in water

This paper focuses on the energetics of glycine, L-alanine, L-phenylalanine and benzene interaction with glycerol (GI) which is one of the most important stabilizing agents of globular proteins in water. The solute-glycerol parameters of pair and triplet interactions have been determined from calorimetric data at 298 and 313 K using standard thermodynamic procedures and compared with previously reported values for ethylene glycol (Eg). The biomolecule interaction with both kosmotropes is found to be enthalpically unfavourable (h(Gl-s) >> 0). The larger hydrophobicity of the solute the larger is the enthalpy of pair interaction. The total interaction is also slightly repulsive in cold water (g(Gl-s) > 0) but reveal a tendency to become attractive at elevated temperatures due to a favourable entropic term (-TsGl-s < 0). The existence of a rather good linear relationship between enthalpic parameters for Eg and Gl solutions has been found. This allows predicting the behavior of different amino acids in aqueous kosmotrope solutions at different temperatures. (C) 2017 Elsevier B.V. All rights reserved.