Protein Aggregation Reactions: Surface Free Energy Model

The energetics of protein reactions can be evaluated in terms of the surface free-energy model, an approach that estimates changes in the surface free energy of proteins from changes in the area and the charge density of the protein-water interface. This approach has given insight into the reactions of proteins in solution as well as in membranes (receptors and voltage-gated channels). The model highlights the importance of pH and thermal changes in aggregation reactions. It also enables a correct interpretation of the Hill equation describing co-operative reactions, since the Hill coefficient is related to a Gibbs surface excess that varies with the degree of reaction.