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

Abstract

The authors 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 the lattice model for excitation migration and trapping in arrays of photosynthetic pigments. Based on this model, the 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 )700, respectively. The predicted average single-step transfer time for excitation transfer between core antenna pigments is 0.21 +/-more » 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.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Univ. of Chicago, IL (United States)
OSTI Identifier:
6061597
Resource Type:
Journal Article
Journal Name:
Proc. Natl. Acad. Sci. U.S.A.; (United States)
Additional Journal Information:
Journal Volume: 84:6
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; PHOTOSYNTHETIC REACTION CENTERS; ELECTRON TRANSFER; FLUORESCENCE; CHLAMYDOMONAS; CHLOROPHYLL; EXCITATION; PHOTOSYNTHESIS; ALGAE; CARBOXYLIC ACIDS; CHEMICAL REACTIONS; ENERGY-LEVEL TRANSITIONS; HETEROCYCLIC ACIDS; HETEROCYCLIC COMPOUNDS; LUMINESCENCE; MICROORGANISMS; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; PHOTOCHEMICAL REACTIONS; PHYTOCHROMES; PIGMENTS; PLANTS; PORPHYRINS; PROTEINS; SYNTHESIS; UNICELLULAR ALGAE; 140505* - Solar Energy Conversion- Photochemical, Photobiological, & Thermochemical Conversion- (1980-)

Citation Formats

Owens, T G, Webb, S P, Mets, L, Alberte, R S, and Fleming, G R. Antenna size dependence of fluorescence decay in the core antenna of photosystem I: estimates of charge separation and energy transfer rates. United States: N. p., 1987. Web. doi:10.1073/pnas.84.6.1532.
Owens, T G, Webb, S P, Mets, L, Alberte, R S, & Fleming, G R. Antenna size dependence of fluorescence decay in the core antenna of photosystem I: estimates of charge separation and energy transfer rates. United States. https://doi.org/10.1073/pnas.84.6.1532
Owens, T G, Webb, S P, Mets, L, Alberte, R S, and Fleming, G R. 1987. "Antenna size dependence of fluorescence decay in the core antenna of photosystem I: estimates of charge separation and energy transfer rates". United States. https://doi.org/10.1073/pnas.84.6.1532.
@article{osti_6061597,
title = {Antenna size dependence of fluorescence decay in the core antenna of photosystem I: estimates of charge separation and energy transfer rates},
author = {Owens, T G and Webb, S P and Mets, L and Alberte, R S and Fleming, G R},
abstractNote = {The authors 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 the lattice model for excitation migration and trapping in arrays of photosynthetic pigments. Based on this model, the 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 )700, 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.},
doi = {10.1073/pnas.84.6.1532},
url = {https://www.osti.gov/biblio/6061597}, journal = {Proc. Natl. Acad. Sci. U.S.A.; (United States)},
number = ,
volume = 84:6,
place = {United States},
year = {Sun Mar 01 00:00:00 EST 1987},
month = {Sun Mar 01 00:00:00 EST 1987}
}