# Improved Statistics for Determining the Patterson Symmetry fromUnmerged Diffraction Intensities

## Abstract

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.

- Authors:

- Publication Date:

- Research Org.:
- Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)

- Sponsoring Org.:
- USDOE; National Institutes of Health. National Institute ofGeneral Medical Sciences Grant 1P50GM62412

- OSTI Identifier:
- 881408

- Report Number(s):
- LBNL-58714

R&D Project: 864D6C

- DOE Contract Number:
- DE-AC02-05CH11231; NIH1P50GM62412

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Applied Crystallography; Journal Volume: 39; Journal Issue: pt2; Related Information: Journal Publication Date: 04/2006

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 59; automation macromolecular LABELIT

### Citation Formats

```
Sauter, Nicholas K., Grosse-Kunstleve, Ralf W., and Adams, Paul D.
```*Improved Statistics for Determining the Patterson Symmetry fromUnmerged Diffraction Intensities*. United States: N. p., 2006.
Web.

```
Sauter, Nicholas K., Grosse-Kunstleve, Ralf W., & Adams, Paul D.
```*Improved Statistics for Determining the Patterson Symmetry fromUnmerged Diffraction Intensities*. United States.

```
Sauter, Nicholas K., Grosse-Kunstleve, Ralf W., and Adams, Paul D. Mon .
"Improved Statistics for Determining the Patterson Symmetry fromUnmerged Diffraction Intensities". United States.
doi:. https://www.osti.gov/servlets/purl/881408.
```

```
@article{osti_881408,
```

title = {Improved Statistics for Determining the Patterson Symmetry fromUnmerged Diffraction Intensities},

author = {Sauter, Nicholas K. and Grosse-Kunstleve, Ralf W. and Adams, Paul D.},

abstractNote = {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.},

doi = {},

journal = {Journal of Applied Crystallography},

number = pt2,

volume = 39,

place = {United States},

year = {Mon Jan 09 00:00:00 EST 2006},

month = {Mon Jan 09 00:00:00 EST 2006}

}