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How do proteins regulate the driving force of excitation transfer in a photosynthetic marine algae?

This contribution presents a detalied theoretical study on how proteins regulate the electronic couplings responsible for exciton delocalization and electronic energy transfer (EET) in photosynthetic pigmentprotein complexes. Understanding environment effects, which cause line broadening and screen electronic interactions, is fundamentally important because of its central role in the control of EET dynamics. Recent work has furthermore shown that simple models for solvation may not be sufficient to explain effects that go beyond Förster theory, such as coherent contribution to energy transfer. Here, we focus on the phycobiliprotein PE545 from the unicellular photosynthetic cryptophyte algae Rhodomonas CS24,3 and apply a novel combined quantum mechanics/molecular mechanics (QM/MM) method4 that explicitly incorporates environment polarization (protein and solvent) at the atomic level on the calculation of site energies and electronic couplings, thus going beyond the continuum dielectric approximation. In addition, we run molecular dynamics (MD) simulations of the PE545 complex in order to explore the effect of protein structural motions on the predicted properties. Our results unveil strong variations in the effective dielectric properties experienced by the different pigmet pairs in the PE545 system. In addition, our results provide insights into the limitations of structure-based methods based on the crystal structure, as opposed to the averaged-structure picture obtained from MD simulations

Universitat de Girona. Departament de Química

Universitat de Girona. Institut de Química Computacional

Author: Curutchet, Carles
Date: 2010 July 5
Abstract: This contribution presents a detalied theoretical study on how proteins regulate the electronic couplings responsible for exciton delocalization and electronic energy transfer (EET) in photosynthetic pigmentprotein complexes. Understanding environment effects, which cause line broadening and screen electronic interactions, is fundamentally important because of its central role in the control of EET dynamics. Recent work has furthermore shown that simple models for solvation may not be sufficient to explain effects that go beyond Förster theory, such as coherent contribution to energy transfer. Here, we focus on the phycobiliprotein PE545 from the unicellular photosynthetic cryptophyte algae Rhodomonas CS24,3 and apply a novel combined quantum mechanics/molecular mechanics (QM/MM) method4 that explicitly incorporates environment polarization (protein and solvent) at the atomic level on the calculation of site energies and electronic couplings, thus going beyond the continuum dielectric approximation. In addition, we run molecular dynamics (MD) simulations of the PE545 complex in order to explore the effect of protein structural motions on the predicted properties. Our results unveil strong variations in the effective dielectric properties experienced by the different pigmet pairs in the PE545 system. In addition, our results provide insights into the limitations of structure-based methods based on the crystal structure, as opposed to the averaged-structure picture obtained from MD simulations
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Citation: Curutchet, C. (2010). How do proteins regulate the driving force of excitation transfer in a photosynthetic marine algae?. A ’IX Girona Seminar’. Girona: Universitat. [Consulta 3 setembre 2010]. Disponible a: http://hdl.handle.net/10256.1/1676
Document access: http://hdl.handle.net/10256.1/1676
Language: eng
Publisher: Universitat de Girona. Departament de Química
Universitat de Girona. Institut de Química Computacional
Collection: IX Girona Seminar
Rights: Aquest document està subjecte a una llicència Creative Commons: Reconeixement - No comercial - Compartir igual (by-nc-sa)
Rights URI: http://creativecommons.org/licenses/by-nc-sa/3.0/es/deed.ca
Subject: Química quàntica -- Congressos
Quantum chemistry -- Congresses
Title: How do proteins regulate the driving force of excitation transfer in a photosynthetic marine algae?
Type: info:eu-repo/semantics/lecture
Repository: DUGiMedia

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