Degree of linear polarization method for determination of intrinsic optical anisotropy of southern bean mosaic virus

Southern bean mosaic virus (SBMV) is a spherical plant virus. It possesses an intrinsic (structural) anisotropy due to the orientation of valence bonds of the amino acid and/or nucleic acid residues. According to the light scattering theory of Rayleigh and Gans for optically anisotropic spheres, the degree of linear polarization of the scattered light depends on the intrinsic anisotropy, the relative refractive index of the sphere to the solvent, the scattering angle, and the inclination angle of linearly polarized incident light to the scattering plane. By using the theoretical expression of the degree of linear polarization, the intrinsic anisotropy parameter of southern bean mosaic virus in the compact spherical state was calculated with the appropriate experimental values. This novel method should be useful in elucidating the internal structure of spherical viruses and other spherical complexes of macromolecules. © 1993 John Wiley & Sons, Inc.