International
Tables for
Crystallography
Volume F
Crystallography of biological macromolecules
Edited by M. G. Rossmann and E. Arnold

International Tables for Crystallography (2006). Vol. F. ch. 21.1, p. 501   | 1 | 2 |

Section 21.1.7.1.6. Unit-cell parameters

G. J. Kleywegta*

aDepartment of Cell and Molecular Biology, Uppsala University, Biomedical Centre, Box 596, SE-751 24 Uppsala, Sweden
Correspondence e-mail: gerard@xray.bmc.uu.se

21.1.7.1.6. Unit-cell parameters

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The accuracy of unit-cell parameters has been shown to be grossly overestimated for small-molecule crystal structures (Taylor & Kennard, 1986[link]). Not intimidated by this observation, some macromolecular crystallographers routinely quote unit-cell axes of 100–200 Å with a precision of 0.01 Å. An analysis of several high-resolution protein crystal structures has revealed that surprisingly large errors in the unit-cell parameters appear to be quite common (at least if synchrotron sources are used for data collection; EU 3-D Validation Network, 1998[link]). Such errors can be detected a posteriori by checking if the bond lengths in a model show any systematic, perhaps direction-dependent, variations from their target values.

References

First citationEU 3-D Validation Network (1998). Who checks the checkers? Four validation tools applied to eight atomic resolution structures. J. Mol. Biol. 276, 417–436.Google Scholar
First citation Taylor, R. & Kennard, O. (1986). Accuracy of crystal structure error estimates. Acta Cryst. B42, 112–120.Google Scholar








































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