Physico-chemical studies on the 11S globulin in soybean seeds: size and shape determination of the molecule.

The molecular shape of the 11S globulin, the major storage protein of soybean seeds, was estimated to be an oblate ellipsoid with a revolution axial ratio of 8.11-8.38 with or without scarce hydration according to the procedure of Simha & Perrin by measuring the partial specific volume, diffusion coefficient, molecular weight and volume fraction intrinsic viscosity. The length of the major axis of the molecule is 178-180 A and that of the minor axis 22 A. Subsequently, the shape factor beta, and the hydrodynamically effective volume, Ve, of the protein were calculated by the procedure of Scheraga & Mandelkern. Consequently, the 11S globulin molecule was also an oblate ellipsoid from beta. Ve was found to be equal to MV/N, the anhydrous volume of protein. It was therefore concluded that the protein existed in a rigid and nearly anhydrous state in solution.