Recursive direct phasing with reference-beam diffraction.
The reference-beam diffraction technique provides a practical way to measure a large number of triplet phases in a standard oscillating-crystal diffraction experiment for protein crystals. The triplet-phase data set from such reference-beam measurements contains a unique phase-occurrence pattern that leads to a new recursive phasing algorithm for the individual structure-factor phases. Application of the new algorithm is demonstrated for tetragonal lysozyme using 7360 triplet phases measured in a reference-beam experiment with a median phase discrepancy of 45 degrees. An electron-density map obtained using this phasing algorithm and the measured triplet phases shows good agreement with the known protein structure.
Shen
Qun
Q
Cornell High Energy Synchrotron Souce (CHESS) and Department of Materials Science and Engineering, Cornell University, USA. qs11@cornell.edu
Wang
Jun
J
D000465:Algorithms; D009113:Muramidase / Q000737:chemistry; D055672:Static Electricity; D014961:X-Ray Diffraction / Q000379:methods*
D009113:Muramidase