help button home button Biophys. J.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Originally published as Biophys J. BioFAST on January 20, 2006.
doi:10.1529/biophysj.105.069286
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
biophysj.105.069286v1
90/7/2486    most recent
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Polli, D.
Right arrow Articles by Cogdell, R. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Polli, D.
Right arrow Articles by Cogdell, R. J.
Biophysical Journal 90:2486-2497 (2006)
© 2006 The Biophysical Society

Carotenoid-Bacteriochlorophyll Energy Transfer in LH2 Complexes Studied with 10-fs Time Resolution

Dario Polli *, Giulio Cerullo *, Guglielmo Lanzani *, Sandro De Silvestri *, Hideki Hashimoto {dagger} and Richard J. Cogdell {ddagger}

* ULTRAS-INFM, Dipartimento di Fisica, Politecnico di Milano, Milan, Italy; {dagger} "Light and Control", PRESTO/JST, Department of Physics, Osaka City University, Osaka, Japan; and {ddagger} Division of Biochemistry and Molecular Biology, Institute of Biological and Life Sciences, University of Glasgow, Glasgow, United Kingdom

Correspondence: Address reprint requests to D. Polli, Tel.: 39-02-23-99-60-86; E-mail: dario.polli{at}polimi.it.

In this report, we present a study of carotenoid-bacteriochlorophyll energy transfer processes in two peripheral light-harvesting complexes (known as LH2) from purple bacteria. We use transient absorption spectroscopy with {approx}10 fs temporal resolution, which is necessary to observe the very fast energy relaxation processes. By comparing excited-state dynamics of the carotenoids in organic solvents and inside the LH2 complexes, it has been possible to directly evaluate their energy transfer efficiency to the bacteriochlorophylls. In the case of okenone in the LH2 complex from Chromatium purpuratum, we obtained an energy transfer efficiency of {eta}ET2 = 63 ± 2.5% from the optically active excited state (S2) and {eta}ET1 = 61 ± 2% from the optically dark state (S1); for rhodopin glucoside contained in the LH2 complex from Rhodopseudomonas acidophila these values become {eta}ET2 = 49.5 ± 3.5% and {eta}ET1 = 5.1 ± 1%. The measurements also enabled us to observe vibrational energy relaxation in the carotenoids' S1 state and real-time collective vibrational coherence initiated by the ultrashort pump pulses. Our results are important for understanding the dynamics of early events of photosynthesis and relating it to the structural arrangement of the chromophores.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2006 by the Biophysical Society.