ISSN:
1399-0047
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
Two types of pseudo-translation symmetry, pseudo-twofold translational symmetry and pseudo-body-centered symmetry, have been found in protein crystals of chorismate mutase and cyclophilin C. Statistics on diffraction intensity from these two crystals showed that the presence of pseudo-translations in atomic space yielded a distribution of systematically strong and weak reflections at low resolution. The diffraction pattern resulting from pseudo-translational symmetry was apparently similar to that from true crystallographic symmetry at 4 Å resolution, but was distinct at high resolution. Pseudo-translation can be detected by comparing the average magnitudes of certain parity groups of reflections in three-dimensional hkl space. Based on the structures of chorismate mutase and cyclophilin C, the ratio of 〉1.2 for the average magnitudes of parity groups is sufficient to indicate the existence of pseudo-translation. Although pseudo-translation often makes structure determination more difficult, the additional information of pseudo-translation has been used successfully in the structure determination of chorismate mutase by multiple isomorphous replacement and of cyclophilin C by molecular replacement. Thus, examination of pseudo-translation is recommended at an early stage of structure determination.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0907444997020064
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