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Improved R-factors for diffraction data analysis in macromolecular crystallography

1997; Nature Portfolio; Volume: 4; Issue: 4 Linguagem: Inglês

10.1038/nsb0497-269

1545-9993

Kay Diederichs, P. Andrew Karplus,

Protein Structure and Dynamics

The quantity Rsym (also called Rmerge) is almost universally used for describing X-ray diffraction data quality. Here, we prove that Rsym is seriously flawed, because it has an implicit dependence on the redundance of the data. A corrected R-factor, Rmeas, is introduced as the equivalent robust indicator of data consistency. In addition, we introduce Rmrgd an R-factor that reflects the gain in accuracy upon averaging of equivalent reflections, as a useful indicator of the quality of reduced data. These new data quality indicators better reveal the benefits of highly redundant data and should stimulate improvements in data quality through increased merging of data from multiple crystals.