A study has been carried out of the interactions with proteins of solvent systems which are commonly used to stabilize proteins in solution or to crystallize proteins out of solution. The first class consisted of water-sucrose and water-glycerol, which are frequently added to enzyme solutions in order to maintain their activity; the second class contained sodium and ammonium sulfates and 2-methyl-2,4-pentanediol (MPD) as solvent components. Densimetry and differential refractometry experiments with the application of multicomponent thermodynamic theory, showed that, in all four systems, proteins are preferentially hydrated, i.e., addition of these cosolvents results in an unfavorable free energy change. Detailed analysis of the thermodynamics of protein transitions in the presence of sucrose showed that its stabilizing action can be accounted for to a great extent in terms of the surface energy of this solvent system.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Colloid and Surface Chemistry