Weak data do not make a free lunch, only a cheap meal. (1st February 2014)

• Record Type: Journal Article
• Authors: Luo, Zhipu; Rajashankar, Kanagalaghatta; Dauter, Zbigniew
• Is Part Of: Acta crystallographica. Volume 70:Part 2(2014:Feb.)
• Page Start: 253
• Page End: 260
• Publication Date: 2014-02-01
• Subjects: Biomolecules -- Structure -- Periodicals; Physical biochemistry -- Periodicals; X-ray crystallography -- Periodicals; Crystallography -- Periodicals; 572
• DOI: 10.1107/S1399004713026680
• Languages: English
• ISSNs: 0907-4449

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Four data sets were processed at resolutions significantly exceeding the criteria traditionally used for estimating the diffraction data resolution limit. The analysis of these data and the corresponding model‐quality indicators suggests that the criteria of resolution limits widely adopted in the past may be somewhat conservative. Various parameters, such as <italic>R</italic><sub>merge</sub> and <italic>I</italic>/σ(<italic>I</italic>), optical resolution and the correlation coefficients CC<sub>1/2</sub> and CC*, can be used for judging the internal data quality, whereas the reliability factors <italic>R</italic> and <italic>R</italic><sub>free</sub> as well as the maximum‐likelihood target values and real‐space map correlation coefficients can be used to estimate the agreement between the data and the refined model. However, none of these criteria provide a reliable estimate of the data resolution cutoff limit. The analysis suggests that extension of the maximum resolution by about 0.2 Å beyond the currently adopted limit where the <italic>I</italic>/σ(<italic>I</italic>) value drops to 2.0 does not degrade the quality of the refined structural models, but may sometimes be advantageous. Such an extension may be particularly beneficial for significantly anisotropic diffraction. Extension of the maximum resolution at the stage of data collection and structure refinement is cheap in terms of the required effort and is definitely more advisable than accepting a too conservative resolution cutoff, which is unfortunately quite frequent among the crystal structures deposited in the Protein Data Bank.</p> </abstract>