Acta Crystallographica Section D

Biological Crystallography

Volume 64, Part 2 (February 2008)

research papers

Acta Cryst. (2008). D64, 172-177 [ doi:10.1107/S0907444907058659 ]

Rapid and automated substructure solution by Shake-and-Bake

H. Xu and C. M. Weeks

Abstract: Direct methods of phase determination have played an important role in determining heavy-atom substructures from difference amplitudes of native-derivative crystal pairs or crystals containing anomalously scattering atoms. The minimal principle-based Shake-and-Bake procedure is one of the most successful direct methods for heavy-atom substructure determination. The computer program SnB, which implements the Shake-and-Bake procedure and is part of the protein structure-determination package BnP, has recently been optimized for rapid and automated substructure determination. Specifically, SnB has been upgraded with (i) a newly developed statistical minimal function for higher success rates, (ii) an optimal FFT grid size for dramatic cost-effectiveness improvement, (iii) a dynamic figure of merit for automatic substructure-solution detection and (iv) a strategy of alternation of anomalous differences with isomorphous dispersive differences for virtually guaranteed substructure solution.

Keywords: Shake-and-Bake; substructure solution; direct methods.