Figure 2.

Salt-specific effects on Debye ratios KC_Lys/R and mutual diffusivities D_m of lysozyme. Plot of (top row) the Debye ratios KC_Lys/R and (bottom row) mutual diffusivities D_m of lysozyme as function of lysozyme concentration C_Lys, in the presence of MgCl₂, NaCl, or CsCl, at increasing concentrations (○, 50 mM; •, 250 mM; □, 625 mM; and ■, 1 M). The y axis intercepts of the Debye plots yields the inverse of the molecular weight M of lysozyme, whereas the sign of the slope indicates whether interactions among the lysozyme molecules are either net repulsive (positive slope) or attractive (negative slope). For the plots of mutual diffusivities, the y axis intercepts yield the free particle diffusivity D₀ at the given solution viscosity, whereas the slope indicates the magnitude and sign of the combined effects of direct and hydrodynamic interactions on mutual lysozyme diffusion. All measurements shown were taken at T = 25°C.