Use of the minimal function for partial structure development in direct methods

Abstract

The shake-and-bake procedure, which is based on the minimal function, has been tested and shown to be extremely effective in molecular-fragment recycling applications. Correctly positioned fragments as small as 5% of the scattering power of the structure typically have a 50% chance of producing a solution in a single recycling trial. While starting models for tangent-formula recycling methods normally require an average r.m.s, displacement error of less than -0.25 A from the refined structure to ensure an adequate chance of success, the shakeand-bake method often tolerates r.m.s, model errors well in excess of 0.5 A. Tests indicate that the new method can outperform traditional tangent-formula procedures in difficult structural applications involving multiple copies of pseudosymmetrically related molecules or low-resolution data.

The high-resolution crystal structure of the molybdate-dependent transcriptional regulator (ModE) from Escherichia coli: a novel combination of domain folds

“…The homodimer that constitutes the asymmetric unit contains six selenomethionines. Anomalous difference Pattersons were analysed with RSPS (Knight, 1989) and in addition, FA values extracted using REVISE (Fan et al ., 1993) and input to the direct methods program RANTAN (Langs et al ., 1995). The independent methods yielded three common Se sites.…”