Abstract
The Fenna-Matthews-Olson (FMO) light-harvesting complex is now one of the primary model systems for the study of excitation energy transfer (EET). However, the mechanism of the EET in this system is still controversial. In this work, molecular dynamics simulations and the electrostatic-embedding quantum-mechanics/molecular-mechanics single-point calculations have been employed to predict the energy transfer pathways utilizing the polarized protein-specific charge (PPC), which provides a more realistic description of Coulomb interaction potential in the protein than conventional mean-field charge scheme. The recently discovered eighth pigment has also been included in this study. Comparing with the conventional mean-field charges, more stable structures of FMO complex were found under PPC scheme during molecular dynamic simulation. Based on the electronic structure calculations, an exciton model was constructed to consider the couplings during excitation. The results show that pigments 3 and 4 dominate the lowest exciton levels whereas the highest exciton level are mainly constituted of pigments 1 and 6. This observation agrees well with the assumption based on the spatial distribution of the pigments. Moreover, the obtained spectral density in this study gives a reliable description of the diverse local environment embedding each pigment.
Highlights
In photosynthesis, sunlight is captured by light-harvesting antenna system, and the electronic excitation energy is transferred from the antenna to the reaction center (RC) and converted into a more stable chemical form
The protein is found more stable under protein-specific charge (PPC) than it is under AMBER charges
The full width at half maximum (FWHM) of these distributions are about 0.1–0.15 Å and the peak positions deviate from their corresponding crystal structure values by less than 0.05 Å
Summary
Sunlight is captured by light-harvesting antenna system, and the electronic excitation energy is transferred from the antenna to the reaction center (RC) and converted into a more stable chemical form. These studies suggested that BChl 8, which resides in the proximity of the chlorosome, has a very large transition energy It receives a significant part of excitation from chlorosome and plays an important role in energy transfer process. Note that these sets of site energies are quite different from each other due that the distinct methods were employed in these studies, leading to diverse pictures of transport dynamics. The result depicts a more reasonable energy ladder, which agrees with the experimental observation and phenomenological description based on the seven-site model[6] It can be conjectured from this study that pigment 8 may not play an important role in the excitation energy transfer (EET) through FMO complex[9,12]. The resulting kBλT / γg , a key parameter for energy transfer efficiency, is in the optimal range, enabling a nearly perfect energy transfer[28]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
