Combining direct methods with isomorphous replacement or anomalous scattering data. I
نویسندگان
چکیده
منابع مشابه
Enantiomorphous phase doublets from isomorphous replacement or anomalous scattering
A direct-methods procedure has been proposed for separating the phase doublet resulting from the use of either isomorphous replacement or anomalous scattering techniques. The phase doublet is expressed as ~#u= ~h±lA~.l. Formulae combining the structure-factor relationships with the phase-doublet information are given. Problems concerning the practical applications are also discussed. A test cal...
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Substantial highly correlated differences sometimes exist between a series of heavy-atom derivatives of a macromolecule and the native structure. Use of such a series of derivatives for phase determination by multiple isomorphous replacement (MIR) has been difficult because MIR analysis has treated errors as independent. A simple Bayesian approach has been used to derive probability distributio...
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Information on the preparation and characterization of heavy-atom derivatives of protein crystals has been collected, either from the literature or directly from protein crystallographers, and assembled in the form of a heavy-atom data bank (HAD). The data bank contains coordinate data for the heavy-atom positions in a form that is compatible with the crystallographic data in the Brookhaven Pro...
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The electron density function, Q(r), in a crystal determines its diffraction pattern, i.e. both the magnitudes and phases of its x-ray diffraction maxima, and conversely. If, however, as is always the case, only magnitudes are available from the diffraction experiment, then the density function ρ(r) cannot be recovered. If one invokes prior structural knowledge, usually that the crystal is comp...
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and refinement was usually complete after ten to fifteen cycles. The refined values of the parameters compared well with the Rossmann programme values, except for the effective atomic numbers, which were uniformly smaller than indicated by the Rossmann programme. The Hart hO1 values were used in the 2 /~. Fourier synthesis, although there may be some question remaining about the proper Z values...
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ژورنال
عنوان ژورنال: Acta Crystallographica Section A Foundations of Crystallography
سال: 1984
ISSN: 0108-7673
DOI: 10.1107/s0108767384001045