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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1987 Mar;84(6):1532–1536. doi: 10.1073/pnas.84.6.1532

Antenna size dependence of fluorescence decay in the core antenna of photosystem I: estimates of charge separation and energy transfer rates.

T G Owens, S P Webb, L Mets, R S Alberte, G R Fleming
PMCID: PMC304469  PMID: 3550793

Abstract

We have examined the photophysics of energy migration and trapping in photosystem I by investigating the spectral and temporal properties of the fluorescence from the core antenna chlorophylls as a function of the antenna size. Time-correlated single photon counting was used to determine the fluorescence lifetimes in the isolated P700 chlorophyll a-protein complex and in a mutant of Chlamydomonas reinhardtii that lacks the photosystem II reaction center complex. The fluorescence decay in both types of sample is dominated by a fast (15-45 psec) component that is attributed to the lifetime of excitations in the photosystem I core antenna. These excitations decay primarily by an efficient photochemical quenching on P700. The measured lifetimes show a linear relationship to the core antenna size. A linear dependence of the excitation lifetime on antenna size was predicted previously in a lattice model for excitation migration and trapping in arrays of photosynthetic pigments [Pearlstein, R.M. (1982) Photochem. Photobiol. 35, 835-844]. Based on this model, our data predict a time constant for photochemical charge separation in the photosystem I reaction center of 2.8 +/- 0.7 or 3.4 +/- 0.7 psec, assuming monomeric or dimeric P700, respectively. The predicted average single-step transfer time for excitation transfer between core antenna pigments is 0.21 +/- 0.04 psec. Under these conditions, excitation migration in photosystem I is near the diffusion limit, with each excitation making an average of 2.4 visits to the reaction center before photoconversion.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. BRODY S. S., RABINOWITCH E. Excitation lifetime of photosynthetic pigments in vitro and in vivo. Science. 1957 Mar 22;125(3247):555–555. doi: 10.1126/science.125.3247.555. [DOI] [PubMed] [Google Scholar]
  2. Breton J., Martin J. L., Migus A., Antonetti A., Orszag A. Femtosecond spectroscopy of excitation energy transfer and initial charge separation in the reaction center of the photosynthetic bacterium Rhodopseudomonas viridis. Proc Natl Acad Sci U S A. 1986 Jul;83(14):5121–5125. doi: 10.1073/pnas.83.14.5121. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Gulotty R. J., Mets L., Alberte R. S., Fleming G. R. Picosecond fluorescence study of photosynthetic mutants of Chlamydomonas reinhardii: origin of the fluorescence decay kinetics of chloroplasts. Photochem Photobiol. 1985 Apr;41(4):487–496. doi: 10.1111/j.1751-1097.1985.tb03516.x. [DOI] [PubMed] [Google Scholar]
  4. Martin J. L., Breton J., Hoff A. J., Migus A., Antonetti A. Femtosecond spectroscopy of electron transfer in the reaction center of the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26: Direct electron transfer from the dimeric bacteriochlorophyll primary donor to the bacteriopheophytin acceptor with a time constant of 2.8 +/- 0.2 psec. Proc Natl Acad Sci U S A. 1986 Feb;83(4):957–961. doi: 10.1073/pnas.83.4.957. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Mullet J. E., Burke J. J., Arntzen C. J. Chlorophyll proteins of photosystem I. Plant Physiol. 1980 May;65(5):814–822. doi: 10.1104/pp.65.5.814. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Shiozawa J. A., Alberte R. S., Thornber J. P. The P700-chlorophyll a-protein. Isolation and some characteristics of the complex in higher plants. Arch Biochem Biophys. 1974 Nov;165(1):388–397. doi: 10.1016/0003-9861(74)90177-5. [DOI] [PubMed] [Google Scholar]
  7. Shubin V. V., Vashchenko R. G., Karapetian N. V. Vzaimodeistvie reaktsionnogo tsentra fotosistemy 1 s antennym khlorofillom v pigment-belkovom komplekse, vydelennom iz khloroplastov gorokha. Mol Biol (Mosk) 1985 May-Jun;19(3):841–850. [PubMed] [Google Scholar]
  8. Vierling E., Alberte R. S. P(700) Chlorophyll a-Protein : Purification, Characterization, and Antibody Preparation. Plant Physiol. 1983 Jul;72(3):625–633. doi: 10.1104/pp.72.3.625. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Woodbury N. W., Becker M., Middendorf D., Parson W. W. Picosecond kinetics of the initial photochemical electron-transfer reaction in bacterial photosynthetic reaction centers. Biochemistry. 1985 Dec 17;24(26):7516–7521. doi: 10.1021/bi00347a002. [DOI] [PubMed] [Google Scholar]

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