Estimation of steric exclusion and differential interaction contributions to protein transfer free energies in aqueous cosolvent solutions

The thermal stability, conformation and aggregation of globular proteins de pend on the concentration and type of cosolvents present in the surrounding aqueous phase. The transfer free energy of proteins into cosolvent solutio ns provides a quantitative description of the influence of cosolvents on pr otein transitions between different states, e.g. folded vs. unfolded or agg regated vs. non-aggregated. An improved understanding of the physiochemical processes contributing to transfer free energies would facilitate the rati onal utilization of proteins as functional ingredients in compositionally c omplex foods. This paper describes a thermodynamic model for predicting ste ric exclusion and differential interaction (protein-dependent and protein-i ndependent) contributions to protein transfer free energies in cosolvent so lutions. The usefulness and limitations of the model are demonstrated by an alyzing published protein transfer free energies. (C) 2001 Elsevier Science Ltd. All rights reserved.