title: Progress on the direct-methods solution of macromolecular structures using single-wavelength anomalous-dispersion (SAS) data.
abstract: In the past few years, a number of strategies have been outlined to resolve the SAS phase ambiguity given that unique estimates omega (h, k) of the triple invariants are available. A new least-squares method is described that can in principle resolve the phase ambiguity to determine macromolecular phases provided that omega (h, k) estimates are unbiased. Limitations of the method in practical applications are discussed. An example is given where the correct solution can be identified by use of the SAS tangent formula in the instance that traditional SAS phasing methods have lead to an incorrect heavy-atom substructure.
authors.affiliation: Hauptman-Woodward Medical Research Institute, Inc., Buffalo, NY 14203, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Langs
authors.forename: R H
authors.initials: RH
authors.lastname: Blessing
authors.forename: D
authors.initials: D
authors.lastname: Guo
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry; D018360:Crystallography, X-Ray / Q000379:methods*; D006096:Gramicidin / Q000737:chemistry; D016018:Least-Squares Analysis; D046911:Macromolecular Substances; D008432:Mathematical Computing; D010455:Peptides; D017671:Platinum Compounds / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D046911:Macromolecular Substances; D010455:Peptides; D017671:Platinum Compounds; C001666:auromomycin; D006096:Gramicidin