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Circular dichroism of carotenoids in bacterial light-harvesting complexes : experiments and modeling

Georgakopoulou, S. and van Grondelle, R. and van der Zwan, G.. (2004) Circular dichroism of carotenoids in bacterial light-harvesting complexes : experiments and modeling. Biophysical journal, Vol. 87, H. 5. pp. 3010-3022.

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Official URL: http://edoc.unibas.ch/dok/A5249170

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Abstract

In this work we investigate the origin and characteristics of the circular dichroism (CD) spectrum of rhodopin glucoside and lycopene in the light-harvesting 2 complex of Rhodopseudomonas acidophila and Rhodospirillum molischianum, respectively. We successfully model their absorption and CD spectra based on the high-resolution structures. We assume that these spectra originate from seven interacting transition dipole moments: the first corresponds to the 0-0 transition of the carotenoid, whereas the remaining six represent higher vibronic components of the S-2 state. From the absorption spectra we get an estimate of the Franck-Condon factors of these transitions. Furthermore, we investigate the broadening mechanisms that lead to the final shape of the spectra and get an insight into the interaction energy between carotenoids. Finally, we examine the consequences of rotations of the carotenoid transition dipole moment and of deformations in the light-harvesting 2 complex rings. Comparison of the modeled carotenoid spectra with modeled spectra of the bacteriochlorophyll Q(Y) region leads to a refinement of the modeling procedure and an improvement of all calculated results. We therefore propose that the combined carotenoid and bacteriochlorophyll CD can be used as an accurate reflection of the overall structure of the light-harvesting complexes.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Structural Biology (Aebi)
UniBasel Contributors:Georgakopoulou, Sofia
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:Biophysical Society
ISSN:0006-3495
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:22 Mar 2012 14:19
Deposited On:22 Mar 2012 13:16

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