Diffusion of bovine serum albumin in a neutral polymer solution

The diffusion coefficient D of bovine serum albumin through various solutions (pH 7.0, 0.5 M NaCl) of polythylene oxide ( M w ∼ 1 × 10 5 , 3 × 10 5 ) was studied with quasielastic light scattering. In solutions of the 1 × 10 5 polymer solution at polymer concentrations above 0.5 g/L, D is considerably greater than would have been expected from the viscosity of water:polymer mixtures, the deviations being larger at low protein concentration that at high protein concentration. With either polymer, D falls with increasing protein concentration.