Volumetric measurements in binary solvents: theory to experiment

Interactions of proteins and protein groups with water-soluble cosolvents have been studied for the last 50 years with a variety of theoretical and experimental methods. The contribution of volumetric techniques to these studies is relatively modest, although volumetric properties of solutes are sensitive to the entire spectrum of solute-solvent and solute-cosolvent interactions. This deficiency is partly related to formidable experimental difficulties related to conducting volumetric measurements at high cosolvent concentrations and partly to the lack of the theoretical framework within which volumetric results can be rationalized in terms of solute-solvent and solute-cosolvent interactions. However, recent years have witnessed a revival of interest in application of the volumetric approach to characterization of solute-solvent interactions in protein solutions in binary mixtures. This review presents an overview of recent advances in the field, focusing on both the theoretical and the experimental developments. While presenting the current state of the art, it also outlines the strategy for future volumetric studies that will result in new insights into the old problem of interactions of proteins with protecting and denaturing osmolytes.