Maximum-likelihood determination of anomalous substructures.

Randy J Read, Airlie J McCoy

OAI: oai:www.repository.cam.ac.uk:1810/275503 • DOI: 10.17863/CAM.22738

A fast Fourier transform (FFT) method is described for determining the substructure of anomalously scattering atoms in macromolecular crystals that allows successful structure determination by X-ray single-wavelength anomalous diffraction (SAD). This method is based on the maximum-likelihood SAD phasing function, which accounts for measurement errors and for correlations between the observed and calculated Bijvoet mates. Proof of principle is shown that this method can improve determination of the anomalously scattering substructure in challenging cases where the anomalous scattering from the substructure is weak but the substructure also constitutes a significant fraction of the real scattering. The method is deterministic and can be fast compared with existing multi-trial dual-space methods for SAD substructure determination.

likelihood single-wavelength anomalous diffraction substructure determination Animals Bacterial Proteins Carbamoyl-Phosphate Synthase (Ammonia) Chick Embryo Crystallography X-Ray Ferredoxins Fourier Analysis Likelihood Functions Macromolecular Substances Muramidase Protein Conformation Thioredoxins