Macromolecular structure solution by charge flipping.
The recently discovered charge-flipping phasing algorithm has received growing interest in small-molecule crystallography and powder diffraction. This computational methodology differs from classical direct methods as it does not require a priori knowledge of either space-group symmetry or chemical composition and does not rely on probabilistic phase relations. Here, it is shown that the charge-flipping algorithm is capable of solving large macromolecular structures with up to approximately 6000 atoms in the asymmetric unit using suitable normalized intensity data at atomic resolution ( approximately 1.0 A). Moreover, it is demonstrated that this algorithm also provides an efficient tool for the experimental phasing of highly complex heavy-atom or anomalous scattering substructures at medium to low resolution ( approximately 2-6 A) that are frequently difficult to determine using Patterson techniques or direct methods. With the present extension to macromolecular crystallography, charge flipping has proved to be a very well performing and general phase-recovery algorithm in all fields of kinematical diffraction.
Dumas
Christian
C
Centre de Biochimie Structurale, CNRS, UMR5048, INSERM U554, Université Montpellier-1, F-34090 Montpellier, France. christian.dumas@cbs.cnrs.fr
van der Lee
Arie
A
D000465:Algorithms; D019295:Computational Biology / Q000379:methods; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry
D009113:Muramidase