Measurements of Multicomponent Diffusion Coefficients for Lysozyme Chloride in Water and Aqueous Na2SO4

This paper presents a diffusion experimental study for ternary lysozymeNa2SO4-water system, from moderate precipitant concentrations into the supersaturated region and provides a complete set of four diffusion coefficients. These data are important in order to provide accurate models of protein diffusion with applications in growth of protein crystals for X-ray diffraction studies. All three-component mutualdiffusion experiments reported here were performed by Rayleigh interferometry at pH= 4.5, T= 25 C and at a mean lysozyme concentration (average of top and bottom solution concentrations) of 0.6 mM (8.6 mg/mL). Four experiments, with different combinations of protein and Na2SO4 concentration differences, were performed at each of five mean Na2SO4 concentrations (0.1, 0.25, 0.5, 0.65 and 0.8 M), for a total of 20 experiments. In addition, we have measured dynamic light-scattering diffusion coefficients of the ternary system lysozyme chloride-Na2SO4-water. Physics Department, Politehnica University, Bucharest, 77206, Romania. Department of Theoretical Physics, National Institute for Physics and Nuclear Engineering, Bucharest-Măgurele, 76900, Romania. Department of Chemistry, Texas Christian University, USA