Glycerol decreases the volume and compressibility of protein interior

Glycerol reduces the apparent specific volume (V) and adiabatic compressibility (K) of protein interiors but enhances it for amino acids. Protein interiors in water exhibit V and K values of 0.784 plus or minus 0.026 mL/g and 12.8 plus or minus 2.5 x 10 to the power -6 mL/g atmosphere. Glycerol dehydrates the protein, decreases the thermal motion of the polypeptide chain, and increases protein stability. The decrease in V and K is probably due to a disintegration of voids in the protein core after the glycerol-stimulated depletion of lubricant water.