Crystallography Research Today is a free monthly online journal that collates and summarizes the latest research about Crystallography, including details on x-ray crystals, techniques, analyses, structures.

Three-dimensional model-free experimental error correction of protein crystal diffraction data with free-R test.

Fu ZQ

Department of Biochemistry and Molecular Biology, The University Of Georgia, Athens, 30602, USA. fuzq@uga.edu

Experimental error correction and scaling is the last step in X-ray diffraction data processing. It is also critical in obtaining good-quality data. In this study, an algorithm is proposed to more generally and efficiently correct experimental error in X-ray crystal diffraction data. With this algorithm, the experimental error is represented by a symbolic three-dimensional function C(xi, eta, t) in the detecting space. Here, (xi, eta) are the coordinates of the diffraction spots on the image and t represents the data-collection time. While the theoretical form of C(xi, eta, t) is not known, it will be determined from the data through computer-aided analysis. The free R(merge) is introduced to check the validity of the solution. The three-dimensional symbolic function does not carry any assumptions and thus can generally account for experimental errors in various X-ray crystal diffraction experiments that are normally too complicated to be described by any fixed formula. Tests will be given to compare the results from different algorithms.

Published 22 November 2005 in Acta Crystallogr D Biol Crystallogr, 61: 1643-8.
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