A group refinement procedure in protein crystallography using Fourier transforms

A rigid-body refinement method and program for crystallography of macromolecules is described. Orientational and translational parameters are refined by fitting the molecular Fourier transforms to the observed structure-factor amplitudes. The range of convergence of the method has been tested on four examples with known crystal structure: PTI, chymotrypsinogen and two forms of α1 anti-trypsin. It was successfully applied in the structure solution of two unknown crystal structures: a third form of α1 anti-trypsin and C-phycocyanin.