Detection and use of pseudo-translation in determination of protein structures

Yuh Min Chook, William N. Lipscomb, K. E. Hengming

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21 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)822-827
Number of pages6
JournalActa Crystallographica Section D: Biological Crystallography
Issue number5
StatePublished - Sep 1 1998

ASJC Scopus subject areas

  • Structural Biology


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