Macromolecular phasing using diffraction from multiple crystal forms

A phasing algorithm for macromolecular crystallography is proposed that utilizes diffraction data from multiple crystal forms - crystals of the same molecule with different unit-cell packings (different unit-cell parameters or space-group symmetries). The approach is based on the method of iterated projections, starting with no initial phase information. The practicality of the method is demonstrated by simulation using known structures that exist in multiple crystal forms, assuming some information on the molecular envelope and positional relationships between the molecules in the different unit cells. With incorporation of new or existing methods for determination of these parameters, the approach has potential as a method for ab initio phasing.

Automated summary

The proposed phasing algorithm for macromolecular crystallography utilizes diffraction data from multiple crystal forms to iteratively determine phase information without initial data. Demonstrated through simulation with known structures in multiple crystal forms, the method shows practicality with the potential for ab initio phasing when combined with other methods.