The Effect of Shape and Concentration on Translational Diffusion of Proteins Measured by PFG NMR

The concentration dependences of self-diffusion coefficient for irregular-shaped fibrinogen, for globular, spheroidal trypsin and alpha-chymotrypsin were studied by pulsed field gradient nuclear magnetic resonance. The experimental data were analyzed in a view of two known theoretical approaches-the hydrodynamic model of rigid spheres by Tokuyama and Oppenheim and the phenomenological approach based on the frictional formalism of non-equilibrium thermodynamics by Vink. The detailed discussion of their merits and drawbacks is presented. Our results testify that the Vink's approach is quite universal, providing a satisfactory description of experimental data for proteins of complicated structure and different shape while the model of Tokuyama and Oppenheim is applicable only to proteins of more regular shape.