Difference structure-factor normalization for heavy-atom or anomalous-scattering substructure determinations

• Published in: Journal of applied crystallography Vol. 32; no. 4; pp. 664 - 670
• Main Authors: Blessing, Robert H., Smith, G. David
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01-08-1999; Blackwell
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Physics; Single-crystal and powder diffraction; Structure of solids and liquids; crystallography; X-ray diffraction and scattering; Probabilistic approach; Structure factors; Structure resolution; Standardization; Theoretical study; XRD; Heavy atom method; Substructure; Selenium Organic compounds; Direct method; Proteins; Anomalous scattering; Amplitude phase
• ISSN: 1600-5767; 0021-8898; 1600-5767
• DOI: 10.1107/S0021889899003416

Procedures are described for normalizing structure‐factor difference magnitudes, |Δ|F||SIR = ||FDer| − |FNat|| ≤ |FHeavy| or |Δ|F||SAS = ||F+h| − |F−h|| ≤ 2|F′′|, to prepare data for probabilistic direct methods phasing to determine heavy‐atom or anomalous‐scattering substructures in SIR (single‐derivative isomorphous replacement) or SAS (single‐wavelength anomalous scattering) cases. Applications of the procedures in several recent determinations of multi‐selenium substructures in selenomethionyl proteins viaSnB direct‐methods phasing are briefly summarized.