The Combination of Phase Information

  • Jan Drenth
Part of the Springer Advanced Texts in Chemistry book series (SATC)


In the multiple isomorphous replacement method the phase information from the various heavy atom derivatives and from anomalous scattering is combined by multiplying the individual phase probability curves. If the electron density map, which results from isomorphous replacement, can be fully interpreted, the crystallographer immediately starts with model refinement and the isomorphous phase information is left behind. However, if the electron density map is inadequate for complete interpretation, map improvement (= phase refinement) should precede model refinement. Solvent flattening and the inclusion of molecular averaging are examples of map improvement techniques (Chapter 8) . Another way to improve the existing model is by combining the isomorphous replacement phase information with phase information from the known part of the structure. It is clear that a general and convenient way of combining phase information from these various sources would be most useful. Such a method has been proposed by Hendrickson and Lattman (1970) and has been based on previous studies by Rossmann and Blow (1961).


Partial Structure Phase Information Model Refinement Phase Probability Anomalous Scattering 
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Copyright information

© Springer Science+Business Media New York 1999

Authors and Affiliations

  • Jan Drenth
    • 1
  1. 1.Laboratory of Biophysical ChemistryGroningenThe Netherlands

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