Calculation of the Macromolecular Size of Bovine Serum Albumin from the Viscosity of Its Aqueous Solutions

Abstract

On the basis of experimental data for the shear viscosity of aqueous bovine serum albumin (BSA) solutions and in the framework of the Malomuzh–Orlov cellular approach, the surface of effective radii of BSA macromolecules has been plotted for the constant pH = 5.2 in the concentration interval of 2.0–27.2 wt% and the temperature interval 278–318 K. A rapid nonlinear increase in the effective radii of BSA macromolecules is shown to take place up to BSA concentrations of about 5 wt% in the whole examined temperature interval. The maxima of the effective radii of BSA macromolecules are observed at a BSA concentration of 5 wt%, and their position is temperature-independent. In the concentration interval 5.0–27.2 wt%, the effective radii of BSA macromolecules decrease, and this reduction is linear at BSA concentrations higher than 10 wt%. A comparison of the calculation results with literature data on the self-diffusion coefficient of macromolecules in solutions testifies to the efficiency of the Malomuzh–Orlov formula for calculating the macromolecular radii of globular proteins on the basis of shear viscosity data for their aqueous solutions.