OVIONE: a new vector-search rotation-function program for macromolecular crystallography

A computer program (OVIONE) that uses a new vector-search rotation function for crystal-structure determination by the molecular-replacement method has been developed. Image-seeking functions have proved to be useful rotation functions in macromolecular crystallography, provided that some conditions on the statistical parameters of both the crystal and the model Patterson maps are fulfilled. An appropriate selection of the vectors involved in the calculation of the image-seeking functions is crucial for the success of the proposed procedure. This selection relies on certain parameters, a careful analysis of which has been performed in order to establish optimal ranges in which the discrimination of the rotation function is enhanced. Finally, the refinement of the highest peaks of the rotation function is carried out by making use of a simple and quick minimization algorithm.