Charge-density study on cyclosporine A

S. K.J. Johnas, B. Dittrich, A. Meents, M. Messerschmidt, E. F. Weckert

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Two single-crystal X-ray diffraction data sets of cyclosporine A were measured to high resolution using synchrotron radiation at temperatures of 5 and 90 K. They allowed an accurate determination of its molecular and electronic structure. Three electron-density models based on pseudoatom scattering factors were compared in terms of derived bond topological properties and in terms of electron-density differences on a grid. In one model multipole parameters were freely refined, whereas in the other two models the density was built up from fixed database parameters from the invariom database and University at Buffalo Databank. The data quality not only allowed benchmarking of the quality of both databases with the refined density, but also judgement of the feasibility of a multipole refinement of a larger oligo-peptide structure such as cyclosporine A. Both databases performed equally well and reproduced the experimentally determined charge density satisfactorily.

Original languageEnglish (US)
Pages (from-to)284-293
Number of pages10
JournalActa Crystallographica Section D: Biological Crystallography
Issue number3
StatePublished - 2009
Externally publishedYes


  • Charge-density studies
  • Cyclosporine A

ASJC Scopus subject areas

  • Structural Biology


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