Lysozyme solubility in H₂O and D₂O solutions as a function of sodium chloride concentration

Some spectroscopic methods require solubilization or crystallization of proteins in heavy water because of the large difference in neutron scattering properties between protons and deuterons. In order to quantify the impact of slightly different physical properties of D₂O and H₂O, lysozyme solubility curves have been measured for these solvents, using 0.2 to 3.0 M sodium chloride in 0.050 M sodium acetate buffer (pH 4.5) at 291 K. After four months of crystallization, solubility data were measured within 9% error and showed that the lysozyme solubility in H₂O is 1.3 times that in D₂O.