Shape determination from solution scattering of biopolymers

Practical aspects of low-resolution shape determination in small-angle scattering studies of biological macromolecules in solution are considered. The shape restoration method using spherical harmonics [Svergun, Volkov, Kozin & Stuhrmann (1996). Acta Cryst. A52, 419-426] is extended to account for deviations from the idealized model and to work directly on raw experimental data sets. An algorithm to restore the structure of homodimeric particles in terms of the shape of the monomer and the separation between the monomers is implemented. Applications of the program to the shape restoration of several proteins, with known and unknown crystal structures, from X-ray solution-scattering data are presented.