International Tables for Crystallography

Structure quality and target parameters
R. A. Engh and R. Huber. International Tables for Crystallography (2006). Vol. F, ch. 18.3, pp. 382-392  [ doi:10.1107/97809553602060000695 ]


Because protein crystals typically diffract to resolutions of 2–3 Å for structures of interest, diffraction data must be supplemented by additional information to be used as parameters for modelling the crystal content. Which information to use, and for what kind of model, depends on the questions to be resolved by the modelled structure. The most obvious choice for target parameters are bond lengths and angles derived from atomic resolution structures. This article describes a set of bond and angle target parameters derived from small-molecule structures in the Cambridge Structural Database and their application to the refinement of protein structure models. Other potential sources of target parameters are also briefly discussed.

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About International Tables for Crystallography

International Tables for Crystallography is the definitive resource and reference work for crystallography. The series consists of nine volumes and comprises articles and tables of data relevant to crystallographic research and to applications of crystallographic methods in all sciences concerned with the structure and properties of materials.