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Title: Spectral variability in phycocyanin cryptophyte antenna complexes is controlled by changes in the α‐polypeptide chains
Author: Corbella Morató, Marina
Cupellini, Lorenzo
Lipparini, Filippo
Scholes, Gregory D.
Curutchet Barat, Carles E.
Keywords: Pèptids
Compostos complexos
Complex compounds
Issue Date: 3-Jun-2019
Publisher: Wiley-VCH Verlag
Abstract: Quantitative models of light harvesting in photosynthetic antenna complexes depend sensitively on the challenging determination of the relative site energies of the pigments. Here we analyze the basis of the light harvesting properties of four antennae from cryptophyte algae, phycocyanines PC577, PC612, PC630 and PC645, by comparing two alternative theoretical strategies to derive the excitonic Hamiltonian. The first is based on molecular dynamics simulations and subsequent polarizable quantum/molecular mechanics (QM/MMPol) calculations, whereas the second is based on three-layer QM/MMPol/ddCOSMO calculations performed on optimized geometries of the pigments, where the water solvent is described using the ddCOSMO continuum model. We find the latter approach to be remarkably accurate, suggesting that these four phycobiliproteins share a common energetic ordering PCB82 < PCB158 < DBV51/61 for pigments located in the highly-conserved β chains, whereas bilins in the more divergent α chains originate their spectral differences. In addition, we predict a strong screening of the coupling among central DBVs in 'open' form complexes PC577 and PC612 compared to 'closed' form ones, which together with the increased interpigment separation explains the attenuation of coherence beatings observed for these complexes.
Note: Versió postprint del document publicat a:
It is part of: ChemPhotoChem, 2019, vol. 3, num. 9, p. 945-956
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ISSN: 2367-0932
Appears in Collections:Articles publicats en revistes (Institut de Química Teòrica i Computacional (IQTCUB))
Articles publicats en revistes (Institut de Recerca Biomèdica (IRB Barcelona))
Articles publicats en revistes (Farmàcia, Tecnologia Farmacèutica i Fisicoquímica)

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