Time-resolved tryptophan fluorescence in photosynthetic reaction centers from Rhodobacter sphaeroides

Valentina I. Godik, Robert E. Blankenship, Timothy P. Causgrove, Neal Woodbury

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Tryptophan fluorescence of reaction centers isolated from Rhodobacter sphaeroides, both stationary and time-resolved, was studied. Fluorescence kinetics were found to fit best a sum of four discrete exponential components. Half of the initial amplitude was due to a component with a lifetime of ≅ 60 ps, belonging to Trp residues, capable of efficient transfer of excitation energy to bacteriochlorophyll molecules of the reaction center. The three other components seem to be emitted by Trp ground-state conformers, unable to participate in such a transfer. Under the influence of intense actinic light, photooxidizing the reaction centers, the yield of stationary fluorescence diminished by {reversed tilde equals}1.5 times, while the number of the kinetic components and their life times remained practically unchanged. Possible implications of the observed effects for the primary photosynthesis events are considered.

Original languageEnglish (US)
Pages (from-to)229-232
Number of pages4
JournalFEBS Letters
Issue number2-3
StatePublished - Apr 26 1993


  • Protein conformation
  • Reaction center
  • Rhodobacter sphaeroides
  • Stationary and time-resolved fluorescence
  • Tryptophan

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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