Generation of models of protein structure from solution scattering experiments

Analytical expressions for the radius of gyration and maximum dimension of compound bodies formed from simple geometric elements are derived. Using principles of symmetry and of commonly observed features of globular protein structures, it is shown how a priori reasonable tertiary and quaternary structures can be distinguished. The formulae, which are simple to apply, permit a rapid comparison of relatively complex shapes, so reducing the amount of computation necessary for a detailed analysis of small angle scattering data. In conjunction with other biophysical data, the morphological parameters derived from scattering curves can be used to generate quite complex biologically reasonable models of protein structures.