Document Detail

Changes in the structure of chlorophyll-protein complexes and excitation energy transfer during photoinhibitory treatment of isolated photosystem I submembrane particles.
MedLine Citation:
PMID:  12167319     Owner:  NLM     Status:  MEDLINE    
The activity of light-induced oxygen consumption, absorption spectra, low temperature (77 K) chlorophyll fluorescence emission and excitation spectra were studied in suspensions of photosystem (PS) I submembrane particles illuminated by 2000 microE m(-2) s(-1) strong white light (WL) at 4 degrees C. A significant stimulation of oxygen uptake was observed during the first 1-4 h of photoinhibitory treatment, which rapidly decreased during further light exposure. Chlorophyll (Chl) content gradually declined during the exposure of isolated PSI particles to strong light. In addition to the Chl photobleaching, pronounced changes were found in Chl absorption and fluorescence spectra. The position of the major peak in the red part of the absorption spectrum shifted from 680 nm towards shorter wavelengths in the course of strong light exposure. A 6-nm blue shift of that peak was observed after 5-h illumination. Even more pronounced changes were found in the characteristics of Chl fluorescence. The magnitude of the dominating long-wavelength emission band at 736 nm located in untreated particles was five times reduced after 2-h exposure, whereas the loss in absolute Chl contents did not exceed 10% of its initial value. The major peak in low-temperature Chl fluorescence emission spectra shifted from 736 to 721 nm after 6-h WL treatment. Individual Chl-protein complexes differed in the response of their absorption spectra to strong WL. Unlike light-harvesting complexes (LHC), LHCI-680 and LHC-730, which did not exhibit changes in the major peak position, its maximum was shifted from 678 to 671 nm in CPIa complex after PSI submembrane particles were irradiated with strong light for 6 h. The results demonstrated that excitation energy transfer represents the stage of photosynthetic utilization of absorbed quanta which is most sensitive to strong light in isolated PSI particles.
S Rajagopal; N Bukhov; R Carpentier
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of photochemistry and photobiology. B, Biology     Volume:  67     ISSN:  1011-1344     ISO Abbreviation:  J. Photochem. Photobiol. B, Biol.     Publication Date:  2002 Jul 
Date Detail:
Created Date:  2002-08-08     Completed Date:  2003-03-04     Revised Date:  2007-07-23    
Medline Journal Info:
Nlm Unique ID:  8804966     Medline TA:  J Photochem Photobiol B     Country:  Switzerland    
Other Details:
Languages:  eng     Pagination:  194-200     Citation Subset:  IM    
Groupe de Recherche en Energie et Information Biomoléculaires, Université du Québec à Trois-Rivières, CP 500 Trois-Rivières, Quebec, Canada G9A 5H7.
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MeSH Terms
Chlorophyll / chemistry*,  metabolism
Electrophoresis, Polyacrylamide Gel
Energy Transfer
Light-Harvesting Protein Complexes
Molecular Structure
Photosynthetic Reaction Center Complex Proteins / antagonists & inhibitors,  metabolism*
Photosystem I Protein Complex
Plant Proteins / chemistry*,  metabolism
Spectrometry, Fluorescence
Reg. No./Substance:
0/Light-Harvesting Protein Complexes; 0/Photosynthetic Reaction Center Complex Proteins; 0/Photosystem I Protein Complex; 0/Plant Proteins; 1406-65-1/Chlorophyll

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