Influence of solvent on dynamics and stability of a protein

Proteins are often dissolved in viscous glass-forming solvents to provide thermal stability and preserve biochemical activity. However, the mechanisms by which this preservation is achieved are unclear. This issue of biopreservation is undoubtedly affected by both thermodynamic and dynamic parameters. The latter parameters will control the rate of conformational transitions of the protein that accompany biological activity. In the present communication we observe variations of local conformational motions of lysozyme in different solvents by using low-frequency Raman spectroscopy. We demonstrate that at low temperatures liquid glycerol provides a stronger suppression of the fast conformational motions of the protein than glassy trehalose. This demonstrates that solvent viscosity is not the only parameter that controls protein dynamics, and details of the protein-solvent interactions might be important in the biopreservation process.