Multichannel Flash Spectroscopy of the Reaction Centers of Wild-type and Mutant Rhodobacter Sphaeroides: BacteriochlorophyllB-mediated Interaction Between the Carotenoid Triplet and the Special Pair

Multichannel flash spectroscopy (with microsecond time resolution) has been applied to carotenoid (Car)-containing and Car-less reaction centers (RC) of Rhodobacter sphaeroides with a view to investigate the interaction between the Car and its neighboring pigments at room temperature. Under neutral...

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Autores: Arellano, Juan B., Melo, Thor Bernt, Fyfe, Paul K., Cogdell, Richard J., Naqvi, K. Razi
Tipo de recurso: artículo
Fecha de publicación:2004
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/3628
Acceso en línea:http://hdl.handle.net/10261/3628
Access Level:acceso abierto
Palabra clave:Reaction center
Rhodobacter sphaeroides
Carotenoids
Bacteriochlorophyll
Triplet energy transfer
P870
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spelling Multichannel Flash Spectroscopy of the Reaction Centers of Wild-type and Mutant Rhodobacter Sphaeroides: BacteriochlorophyllB-mediated Interaction Between the Carotenoid Triplet and the Special PairArellano, Juan B.Melo, Thor BerntFyfe, Paul K.Cogdell, Richard J.Naqvi, K. RaziReaction centerRhodobacter sphaeroidesCarotenoidsBacteriochlorophyllTriplet energy transferP870Multichannel flash spectroscopy (with microsecond time resolution) has been applied to carotenoid (Car)-containing and Car-less reaction centers (RC) of Rhodobacter sphaeroides with a view to investigate the interaction between the Car and its neighboring pigments at room temperature. Under neutral redox potential conditions, where the primary quinone acceptor (QA) is oxidized, the light-induced spectral changes in the 350-1000 nm region are attributed to the photochemical oxidation of the special pair (denoted here as P870), the generation of P870(+)QA(-), and the attendant electrochromism of adjacent chromophores. A bathochromic shift of <1 nm in the visible absorption region of Car reveals the sensitivity of Car to the P870 photooxidation. Under low redox potential conditions, where QA is reduced, P870 triplets (P870(+)) are formed. The time-resolved triplet-minus-singlet (TmS) spectrum of Car-less RC shows a deep bleaching at 870 nm, which belongs to P870(+), and additional (but smaller) bleaching at 800 nm; the entire spectrum decays at the same rate (with a lifetime of about 50 micros). The bleaching at 800 nm arises from the pigment interaction between P870(+) and the accessory bacteriochlorophylls on A and B branches (BA,B). In Car-containing RC, the TmS spectra of Car are accompanied by two smaller, negative signals--a sharp peak at 809 +/- 2 nm and a broad band at 870 nm--which decay at the same rate as the TmS spectrum of Car (ca 10 micros). The former is ascribed to the perturbation, by Car(+), of the absorption spectrum of BB; the latter, to the TmS spectrum of P870(+), a species that appears to be in approximate thermal equilibrium with Car(+). These assignments are consistent with the absorption-detected magnetic resonance spectra obtained by other workers at low temperatures.RJC thanks the Biotechnology and Biological Sciences Research Council for financial support. JBA is very grateful to the European Science Foundation and the Spanish Ministry of Science and Technology for awarding him a travel grant for his visit to Trondheim and Glasgow. Support from the Research Council of Norway (NFR) is also gratefully acknowledged.Peer reviewedAmerican Society for Photobiology200820082004info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501492290 bytesapplication/pdfhttp://hdl.handle.net/10261/3628reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Ingléshttp://www.bioone.org/doi/abs/10.1562/0031-8655%282004%2979%3C68%3AMFSOTR%3E2.0.CO%3B2info:eu-repo/semantics/openAccessoai:digital.csic.es:10261/36282026-05-22T06:33:51Z
dc.title.none.fl_str_mv Multichannel Flash Spectroscopy of the Reaction Centers of Wild-type and Mutant Rhodobacter Sphaeroides: BacteriochlorophyllB-mediated Interaction Between the Carotenoid Triplet and the Special Pair
title Multichannel Flash Spectroscopy of the Reaction Centers of Wild-type and Mutant Rhodobacter Sphaeroides: BacteriochlorophyllB-mediated Interaction Between the Carotenoid Triplet and the Special Pair
spellingShingle Multichannel Flash Spectroscopy of the Reaction Centers of Wild-type and Mutant Rhodobacter Sphaeroides: BacteriochlorophyllB-mediated Interaction Between the Carotenoid Triplet and the Special Pair
Arellano, Juan B.
Reaction center
Rhodobacter sphaeroides
Carotenoids
Bacteriochlorophyll
Triplet energy transfer
P870
title_short Multichannel Flash Spectroscopy of the Reaction Centers of Wild-type and Mutant Rhodobacter Sphaeroides: BacteriochlorophyllB-mediated Interaction Between the Carotenoid Triplet and the Special Pair
title_full Multichannel Flash Spectroscopy of the Reaction Centers of Wild-type and Mutant Rhodobacter Sphaeroides: BacteriochlorophyllB-mediated Interaction Between the Carotenoid Triplet and the Special Pair
title_fullStr Multichannel Flash Spectroscopy of the Reaction Centers of Wild-type and Mutant Rhodobacter Sphaeroides: BacteriochlorophyllB-mediated Interaction Between the Carotenoid Triplet and the Special Pair
title_full_unstemmed Multichannel Flash Spectroscopy of the Reaction Centers of Wild-type and Mutant Rhodobacter Sphaeroides: BacteriochlorophyllB-mediated Interaction Between the Carotenoid Triplet and the Special Pair
title_sort Multichannel Flash Spectroscopy of the Reaction Centers of Wild-type and Mutant Rhodobacter Sphaeroides: BacteriochlorophyllB-mediated Interaction Between the Carotenoid Triplet and the Special Pair
dc.creator.none.fl_str_mv Arellano, Juan B.
Melo, Thor Bernt
Fyfe, Paul K.
Cogdell, Richard J.
Naqvi, K. Razi
author Arellano, Juan B.
author_facet Arellano, Juan B.
Melo, Thor Bernt
Fyfe, Paul K.
Cogdell, Richard J.
Naqvi, K. Razi
author_role author
author2 Melo, Thor Bernt
Fyfe, Paul K.
Cogdell, Richard J.
Naqvi, K. Razi
author2_role author
author
author
author
dc.subject.none.fl_str_mv Reaction center
Rhodobacter sphaeroides
Carotenoids
Bacteriochlorophyll
Triplet energy transfer
P870
topic Reaction center
Rhodobacter sphaeroides
Carotenoids
Bacteriochlorophyll
Triplet energy transfer
P870
description Multichannel flash spectroscopy (with microsecond time resolution) has been applied to carotenoid (Car)-containing and Car-less reaction centers (RC) of Rhodobacter sphaeroides with a view to investigate the interaction between the Car and its neighboring pigments at room temperature. Under neutral redox potential conditions, where the primary quinone acceptor (QA) is oxidized, the light-induced spectral changes in the 350-1000 nm region are attributed to the photochemical oxidation of the special pair (denoted here as P870), the generation of P870(+)QA(-), and the attendant electrochromism of adjacent chromophores. A bathochromic shift of <1 nm in the visible absorption region of Car reveals the sensitivity of Car to the P870 photooxidation. Under low redox potential conditions, where QA is reduced, P870 triplets (P870(+)) are formed. The time-resolved triplet-minus-singlet (TmS) spectrum of Car-less RC shows a deep bleaching at 870 nm, which belongs to P870(+), and additional (but smaller) bleaching at 800 nm; the entire spectrum decays at the same rate (with a lifetime of about 50 micros). The bleaching at 800 nm arises from the pigment interaction between P870(+) and the accessory bacteriochlorophylls on A and B branches (BA,B). In Car-containing RC, the TmS spectra of Car are accompanied by two smaller, negative signals--a sharp peak at 809 +/- 2 nm and a broad band at 870 nm--which decay at the same rate as the TmS spectrum of Car (ca 10 micros). The former is ascribed to the perturbation, by Car(+), of the absorption spectrum of BB; the latter, to the TmS spectrum of P870(+), a species that appears to be in approximate thermal equilibrium with Car(+). These assignments are consistent with the absorption-detected magnetic resonance spectra obtained by other workers at low temperatures.
publishDate 2004
dc.date.none.fl_str_mv 2004
2008
2008
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
format article
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/3628
url http://hdl.handle.net/10261/3628
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv http://www.bioone.org/doi/abs/10.1562/0031-8655%282004%2979%3C68%3AMFSOTR%3E2.0.CO%3B2
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv 492290 bytes
application/pdf
dc.publisher.none.fl_str_mv American Society for Photobiology
publisher.none.fl_str_mv American Society for Photobiology
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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