Rotational electrolyte friction on non-spherical polyions

Here we present an approximate theory, based on the generalized Langevin equation approach to tracer diffusion, which describes the electrolyte friction effects on the rotational diffusion coefficient of non-spherical polyions of axially symmetric (but otherwise arbitrary) shape and charge distribution. This theory is applied to a simple model polyion, a prolate ellipsoid with a linear charge distribution along the line between its foci. The results are compared with the corresponding results for the translational diffusion coefficient. Quantitative predictions are discussed for a concrete experimental system, namely, tobacco mosaic virus in aqueous solution at infinite dilution but variable ionic strength.