Exciton interactions in the light-harvesting antenna of photosynthetic bacteria studied with triplet-singlet spectroscopy and singlet-triplet annihilation on the B820 subunit form of Rhodospirillum rubrum

Frank van Mourik, Cornelis J.R. van der Oord, Kees J. Visscher, Pamela S. Parkes-Loach, Paul A. Loach, Ronald W. Visschers, Rienk van Grondelle*

*Corresponding author for this work

Research output: Contribution to journalArticle

78 Scopus citations

Abstract

The pigment-protein complex, B820, isolated from the long-wavelength antenna (LH-1) of the photosynthetic purple bacterium Rhodospirillum rubrum was studied with polarized nanosecond laser spectroscopy. The polarized triplet (T)-singlet (S) spectrum was obtained at 77 K. The spectrum is significantly different from the T-S spectrum of monomeric BChl a, and can be explained by assuming that upon excitation the absorption band at 825 nm, which is due to a dimeric pair of BChl a molecules, disappears from the absorption spectrum, and is replaced by a monomer absorption band peaking at 809 nm. From the energy-dependence of the triplet yield, the high polarization of the bleaching, and the absence of singlet-triplet quenching we conclude that the B820 complex contains only one dimer of interacting BChl a molecules.

Original languageEnglish (US)
Pages (from-to)111-119
Number of pages9
JournalBBA - Bioenergetics
Volume1059
Issue number1
DOIs
StatePublished - Aug 2 1991

Keywords

  • Bacteriochlorophyll
  • Exciton interaction
  • Photosynthesis

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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