Ab initio protein phasing at 1.4 A resolution

All the techniques today available for the ab initio crystal structure solution of proteins require that the atomicity condition is satisfied. Accordingly, diffraction data at resolution equal or better than 1.2 Angstrom are necessary. This condition reduces the role of the ab initio techniques in macromolecular crystallography. The computer program SIR2002 has been modified in such a way that it may succeed also with 1.4 Angstrom resolution diffraction data. The modifications concern all the modules of the program: the modified program also benefits by the efficiency of a figure of merit.