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Magnetic interactions between the triplet state of the primary donor and the prereduced ubiquinone acceptor in reaction centers of the photosynthetic bacteriumRhodopseudomonas sphaeroides2.4.1

Authors
Journal
Biochimica et Biophysica Acta (BBA) - Bioenergetics
0005-2728
Publisher
Elsevier
Publication Date
Volume
808
Issue
1
Identifiers
DOI: 10.1016/0005-2728(85)90022-2
Keywords
  • Electron Spin Polarization
  • Quinone
  • Esr
  • Bacterial Photosynthesis
  • Reaction Center
  • (Rps. Sphaeroides)

Abstract

Abstract The lineshape of the polarized prereduced primary quinone acceptor of Rhodopseudomonas sphaeroides after a laser flash was studied using time-resolved continuous wave EPR and electron spin echo techniques. The EPR as well as the electron spin echo experiments show that the lineshape of the ubiquinone shortly after a laser flash is time-dependent. This is attributed to magnetic interactions between the ubiquinone and the triplet state of the primary donor. Taking into account both dipolar and exchange interactions, a simulation of the EPR lineshape of the ubiquinone at 50 μs after the laser flash is performed, yielding a distance of 1.85 nm between the primary donor and the primary acceptor. From the simulation it is also concluded that the plane of the ubiquinone is approximately parallel to the surface of the membrane.

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