Investigation of hydration effect of the proteins by phenomenological thermostatistical methods

In this study variations with respect to temperature of entropy increment ΔS, arising in the dissolution of proteins in water, have been investigated by the methods of statistical thermodynamics. In this formalism, effective electric field E and total dipole moment M are taken as thermodynamical variables. The partition function given by Bakk et al. [Physica A 304 (2002) 355-361] has been used in a modified form while obtaining the free energy. In the constructed phenomenological theory, experimental data are taken from the study of Privalov [J. Chem. Thermodyn. 29 (1997) 447-474; J. Mol. Biol. 213 (1990) 385; T.E. Creighton, Protein Folding, W.H. Freeman and Company, New York, 1995, pp. 83-151] and relevant parameters have been found by fitting to experimental curves. The variations of entropy increments ΔS have been investigated in the temperature range 265-350K.