Improved Statistics for Determining the Patterson Symmetry fromUnmerged Diffraction Intensities
We examine procedures for detecting the point-group symmetryof macromolecular datasets and propose enhancements. To validate apoint-group, it is sufficient to compare pairs of Bragg reflections thatare related by each of the group's component symmetry operators.Correlation is commonly expressed in the form of a single statisticalquantity (such as Rmerge) that incorporates information from all of theobserved reflections. However, the usual practice of weighting all pairsof symmetry-related intensities equally can obscure the fact that thevarious symmetry operators of the point-group contribute differingfractions of the total set. In some cases where particular symmetryelements are significantly under-represented, statistics calculatedglobally over all observations do not permit conclusions about thepoint-group and Patterson symmetry. The problem can be avoided byrepartitioning the data in a way that explicitly takes note of individualoperators. The new analysis methods, incorporated into the programLABELIT (cci.lbl.gov/labelit), can be performed early enough during dataacquisition, and are quick enough, that it is feasible to pause tooptimize the data collection strategy.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE; National Institutes of Health. National Institute ofGeneral Medical Sciences Grant 1P50GM62412
- DOE Contract Number:
- DE-AC02-05CH11231; NIH1P50GM62412
- OSTI ID:
- 881408
- Report Number(s):
- LBNL-58714; R&D Project: 864D6C
- Journal Information:
- Journal of Applied Crystallography, Vol. 39, Issue pt2; Related Information: Journal Publication Date: 04/2006
- Country of Publication:
- United States
- Language:
- English
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