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Carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in LH2 from Phaeosprillum molischianum

The peripheral light-harvesting antenna complex (LH2) of purple photosynthetic bacteria is an ideal testing ground for models of structure–function relationships due to its well-determined molecular structure and ultrafast energy deactivation. It has been the target for numerous studies in both theo...

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Autores principales: Thyrhaug, Erling, Lincoln, Craig N., Branchi, Federico, Cerullo, Giulio, Perlík, Václav, Šanda, František, Lokstein, Heiko, Hauer, Jürgen
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer Netherlands 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5783993/
https://www.ncbi.nlm.nih.gov/pubmed/28523607
http://dx.doi.org/10.1007/s11120-017-0398-3
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author Thyrhaug, Erling
Lincoln, Craig N.
Branchi, Federico
Cerullo, Giulio
Perlík, Václav
Šanda, František
Lokstein, Heiko
Hauer, Jürgen
author_facet Thyrhaug, Erling
Lincoln, Craig N.
Branchi, Federico
Cerullo, Giulio
Perlík, Václav
Šanda, František
Lokstein, Heiko
Hauer, Jürgen
author_sort Thyrhaug, Erling
collection PubMed
description The peripheral light-harvesting antenna complex (LH2) of purple photosynthetic bacteria is an ideal testing ground for models of structure–function relationships due to its well-determined molecular structure and ultrafast energy deactivation. It has been the target for numerous studies in both theory and ultrafast spectroscopy; nevertheless, certain aspects of the convoluted relaxation network of LH2 lack a satisfactory explanation by conventional theories. For example, the initial carotenoid-to-bacteriochlorophyll energy transfer step necessary on visible light excitation was long considered to follow the Förster mechanism, even though transfer times as short as 40 femtoseconds (fs) have been observed. Such transfer times are hard to accommodate by Förster theory, as the moderate coupling strengths found in LH2 suggest much slower transfer within this framework. In this study, we investigate LH2 from Phaeospirillum (Ph.) molischianum in two types of transient absorption experiments—with narrowband pump and white-light probe resulting in 100 fs time resolution, and with degenerate broadband 10 fs pump and probe pulses. With regard to the split Q(x) band in this system, we show that vibronically mediated transfer explains both the ultrafast carotenoid-to-B850 transfer, and the almost complete lack of transfer to B800. These results are beyond Förster theory, which predicts an almost equal partition between the two channels. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11120-017-0398-3) contains supplementary material, which is available to authorized users.
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spelling pubmed-57839932018-02-01 Carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in LH2 from Phaeosprillum molischianum Thyrhaug, Erling Lincoln, Craig N. Branchi, Federico Cerullo, Giulio Perlík, Václav Šanda, František Lokstein, Heiko Hauer, Jürgen Photosynth Res Original Article The peripheral light-harvesting antenna complex (LH2) of purple photosynthetic bacteria is an ideal testing ground for models of structure–function relationships due to its well-determined molecular structure and ultrafast energy deactivation. It has been the target for numerous studies in both theory and ultrafast spectroscopy; nevertheless, certain aspects of the convoluted relaxation network of LH2 lack a satisfactory explanation by conventional theories. For example, the initial carotenoid-to-bacteriochlorophyll energy transfer step necessary on visible light excitation was long considered to follow the Förster mechanism, even though transfer times as short as 40 femtoseconds (fs) have been observed. Such transfer times are hard to accommodate by Förster theory, as the moderate coupling strengths found in LH2 suggest much slower transfer within this framework. In this study, we investigate LH2 from Phaeospirillum (Ph.) molischianum in two types of transient absorption experiments—with narrowband pump and white-light probe resulting in 100 fs time resolution, and with degenerate broadband 10 fs pump and probe pulses. With regard to the split Q(x) band in this system, we show that vibronically mediated transfer explains both the ultrafast carotenoid-to-B850 transfer, and the almost complete lack of transfer to B800. These results are beyond Förster theory, which predicts an almost equal partition between the two channels. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11120-017-0398-3) contains supplementary material, which is available to authorized users. Springer Netherlands 2017-05-18 2018 /pmc/articles/PMC5783993/ /pubmed/28523607 http://dx.doi.org/10.1007/s11120-017-0398-3 Text en © The Author(s) 2017 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
spellingShingle Original Article
Thyrhaug, Erling
Lincoln, Craig N.
Branchi, Federico
Cerullo, Giulio
Perlík, Václav
Šanda, František
Lokstein, Heiko
Hauer, Jürgen
Carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in LH2 from Phaeosprillum molischianum
title Carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in LH2 from Phaeosprillum molischianum
title_full Carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in LH2 from Phaeosprillum molischianum
title_fullStr Carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in LH2 from Phaeosprillum molischianum
title_full_unstemmed Carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in LH2 from Phaeosprillum molischianum
title_short Carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in LH2 from Phaeosprillum molischianum
title_sort carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in lh2 from phaeosprillum molischianum
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5783993/
https://www.ncbi.nlm.nih.gov/pubmed/28523607
http://dx.doi.org/10.1007/s11120-017-0398-3
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