Persistent/transient spectral hole burning (HB) and computer simulations are used to provide new insight into the excitonic structure excitation energy transfer of widely studied bacterial reaction center (bRC) Rhodobacter (Rb.) sphaeroides. We focus on site energies its cofactors electrochromic shifts induced in chemically oxidized (P(+)) charge-separated (P(+)QM(-)) states. Theoretical models lead two alternative interpretations H-band. On basis our experimental simulation data, we suggest...

We provide an analysis of the pigment composition reconstituted wild type CP29 complexes. The obtained stoichiometry 9 ± 0.6 Chls a and 3 b per complex, with some possible heterogeneity in carotenoid binding, is agreement 3.5 revealed by modeling low-temperature optical spectra. find that ∼50% Chl b614 lost during reconstitution/purification procedure, whereas are almost fully retained. excitonic structure nature low-energy (low-E) state(s) addressed via simulations (using Redfield theory) 5...

In the photosynthetic green sulfur bacterium Chlorobaculum tepidum, baseplate mediates excitation energy transfer from light-harvesting chlorosome to Fenna–Matthews–Olson (FMO) complex and subsequently toward reaction center (RC). Literature data suggest that is a 2D lattice of BChl a–CsmA dimers. However, recently, it has been proposed, using electronic spectroscopy (2DES) at 77 K, least four excitonically coupled are in close contact within structure [Dostál, J.; et al., J. Phys. Chem....

Identification of the lowest energy pigments in photosynthetic CP47 antenna protein complex Photosystem II (PSII) is essential for understanding its excitonic structure, as well excitation pathways PSII core complex. Unfortunately, there no consensus concerning nature low-energy state(s), nor chlorophyll (Chl) site energies this important antenna. Although we raised concerns regarding estimations Chl obtained from modeling studies various types optical spectra [Reinot, T; et al., Anal. Chem....

This work discusses the protein conformational complexity of B800–850 LH2 complexes from purple sulfur bacterium Allochromatium vinosum, focusing on spectral characteristics B850 chromophores. Low-temperature absorption and split B800 band shift blue red, respectively, at elevated temperatures, revealing isosbestic points. The latter indicates presence two (unresolved) conformations bacteriochlorophylls (BChls), referred to as 1 2, BChls, denoted B800R B800B. energy differences between...

Significant protein rearrangement upon excitation and energy transfer in Fenna–Matthews–Olson of Prosthecochloris aestuarii results a modified landscape, which induces more changes pigment site energies than predicted by the "standard" hole-burning theory. The are elucidated simulations while investigating effects site-dependent disorder, both static (site-energy distribution widths) dynamic (spectral density shapes). resulting optimized their fluctuations consistent with relative...

The B800-850 LH2 antenna from the photosynthetic purple sulfur bacterium Allochromatium vinosum exhibits an unusual spectral splitting of B800 absorption band; i.e., two bands are well-resolved at 5 K with maxima 805 nm (B800R) and 792 (B800B). To provide more insight into nature bacteriochlorophyll (BChl) a molecules, high-resolution hole-burning (HB) spectroscopy is employed. Both white light illumination selective laser excitations B800R or B800B lead to → phototransformation. Selective...

The LH2 antenna complex of the purple bacterium Allochromatium vinosum has a distinct double peak structure 800 nm band (B800). Several hypotheses were proposed to explain its origin. Recent 77 K two-dimensional electronic spectroscopy data suggested that excitonic coupling dimerized bacteriochlorophylls (BChls) within B800 ring is largely responsible for split [M. Schröter et al., J. Phys. Chem. Lett. 2018, 9, 1340]. Here we argue interactions between BChls in ring, though present, are weak...

Recently, a hybrid approach combining solid-state NMR spectroscopy and cryo-electron microscopy showed that the baseplate in green sulfur bacterium Chlorobaculum tepidum is 2D lattice of BChl a–CsmA dimers [Nielsen, J. T.; et al., Nat. Commun. 2016, 7, 12454–12465]. While existence subunit was previously known, proposed orientations pigments had only been elucidated from spectral data up to this point. Regarding electronic structure baseplate, two models have proposed. were interpreted as...

To provide more insight into the excitonic structure and exciton lifetimes of wild type (WT) CP29 complex photosystem II, we measured high-resolution (low temperature) absorption, emission, hole burned spectra for A2 B3 mutants, which lack chlorophylls a612 b614 (Chls), respectively. Experimental modeling results obtained WT A2/B3 mutants new on mutation-induced changes at molecular level shed light energy transfer dynamics. Simulations optical spectra, using second-order non-Markovian...