Thermodynamics of globular proteins

The analysis of temperature-induced unfolding of proteins in aqueous solutions was performed. Based on the data of thermodynamic parameters of protein unfolding and using the method of semi-empirical calculations of hydration parameters at reference temperature 298 K, we obtained numerical values of enthalpy, free energy, and entropy which characterize the unfolding of proteins in the 'gas phase'. It was shown that specific values of the energy of weak intramolecular bonds (∆H^int), conformational free energy (∆G^conf) and entropy (∆S^conf) are the same for proteins with molecular weight 7-25 kDa. Using the energy value (∆H^int) and the proposed approach for estimation of the conformational entropy of native protein (S^NC), numerical values of the absolute free energy (G^NC) were obtained.