The orientation of the primary donor in bacterial photosynthesis

Harry A. Frank, Richard Friesner, John A. Nairn, G. Charles Dismukes, Kenneth Sauer

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)


The triplet state EPR spectra of magnetically aligned whole cells of Rhodopseudomonas viridis and Rhodopseudomonas palustris display a marked dependence on the orientation of the static EPR field with respect to the alignment field direction. This observation implies that the primary donor species on which the triplets are localized are ordered within the membranes. We have developed a theoretical model for the system to enable calculation of the orientation of the magnetic axes of the primary donor species with respect to the membranes in which they reside. The triplet state spectra are generated by an ensemble of partially ordered magnetic systems and a computer simulation of the experimental results. The triplet orientation is very similar for the two organisms studied, where one axis lies predominantly in the plane of the membrane and the other two axes have approximately equal projections onto the normal to the membrane.

Original languageEnglish
Pages (from-to)484-501
Number of pages18
JournalBBA - Bioenergetics
Issue number3
Publication statusPublished - Sep 11 1979


  • (EPR)
  • Bacterial photosynthesis
  • Reaction center
  • Triplet state

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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