Shell model calculations of translational and rotational frictional coefficients

Abstract

Previous work has shown that it is possible to calculate the translational and rotational frictional coefficients of complex structures by modeling them by a surface shell of spherical elements. The basic equations of this shell model method and its application to spheres, prolate ellipsoids of revolution, proteins, and viruses, are reviewed here. Several new results are also presented. It is demonstrated analytically that the rotational frictional coefficient for a sphere, calculated according to the shell model, agrees with the Stokes‐Kirchoff law. The rotational frictional coefficients of right circular cylinders have been calculated by digital computation; end effects are less marked than they are according to a theory of Broersma. Finally, the sedimentation behavior of various geometrical arrays of oligomeric aggregates of spherical subunits has been tabulated, to facilitate application to multichain protein systems.