Quantitative Characterization of the Interaction Between Sucrose and Native Proteins via Static Light Scattering

The composition-dependent static light scattering of binary mixtures of each of four dilute globular proteins and sucrose were measured over a broad range of sucrose concentrations. A conventional analysis of the dependence of excess scattering of a single macrosolute in a continuum solvent yields unphysical results. The data are reanalyzed in the context of multicomponent light scattering theory to yield the dependence of the free energy of solvation of each protein upon the concentration of sucrose. The results could be satisfactorily accounted for by an effective hard particle model that indicates the nature of the underlying interactions between sucrose and each protein.