Predictive First-Principles Modeling of a Photosynthetic Antenna Protein: The Fenna–Matthews–Olson Complex

Abstract

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Towards a quantitative description of excitonic couplings in photosynthetic pigment–protein complexes: quantum chemistry driven multiscale approaches

“…the |l k | 2 of the absorption spectrum (eqn (24)) is replaced by the rotational strength expression is used for the lineshape function, as described earlier. 59,76 This lineshape function includes the low-frequency continuous intermolecular part of the spectral density of the exciton-vibrational coupling.…”

“…An alternative to this brute force approach is to compute individual chromophores at a high level and the interactions between them using a simplified model. 12,13 Chromophores can be treated as fragments in fragment-based approaches, [14][15][16][17][18][19][20][21][22] for some of which the excitonic coupling 23,24 and delocalized excitations 25 can be calculated. The excitonic couplings are responsible for energy transfer, and the delocalization of excited states results in a shift of optical transition energies and a redistribution of oscillator strength measured in optical spectroscopy on molecular aggregates.…”

Analysis of Photosynthetic Systems and Their Applications with Mathematical and Computational Models

“…The multiple excited states observed in the FMO complex are also due to the presence of different BChls in different local environments of the protein. While still debated, the possibility of existence of the long-lived quantum coherence also motivates to intensify the computational studies in different directions including the study of the excitation properties using different types of computational techniques [4,11,13,20,71,94,[132][133][134][135][136][137][138][139][140][141][142].…”

“…Experimentally, the eighth BChl pigment has also been newly resolved in the FMO protein that lies perpendicular to the plane of the other seven BChls [17,18]. Notably, FMO complex is a homotrimer of three ≈ 40 kDa monomer that possesses C3 symmetry whereby three copies of each subunit of seven BChl a chromophores bind together to the eighth BChl a pigment [16,19,20]. Due to close packing of BChl a pigments in each monomer subunit, the excited electronic states of FMO complexes are delocalized over multiple pigments.…”

“…Due to close packing of BChl a pigments in each monomer subunit, the excited electronic states of FMO complexes are delocalized over multiple pigments. The previous research in this field is mainly focused on developing and testing new computational and experimental methods for a better understanding of the delocalization of excited states over multiple pigments and the unfolding of the relationship between atomic structure and absorbance along with the fluorescence spectra [19,20]. Owing to the rotational symmetric of the monomer subunit of FMO trimer around the symmetry axis, there are two types of FMO complex structures widely analyzed in the literature.…”