Parameters of the Protein Energy Landscapes of Several Light-Harvesting Complexes Probed via Spectral Hole Growth Kinetics Measurements

Herascu, Nicoleta; Najafi, Mehdi; Amunts, Alexey; Pieper, Jörg; Irrgang, Klaus−Dieter; Picorel, Rafael; Seibert, Michael; Zazubovich, Valter

doi:10.1021/jp108775y

Cited by 16 publications

(48 citation statements)

References 77 publications

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“…[391]). This is in agreement with theoretical calculations locating the sink at a610, [91] but a604 has also been suggested as a possible sink in LHC-II, [406] in particular at low temperatures. [407] The latter fits to electrostatic calculations assuming a different (less likely) environment conformation for a604.…”

Section: Energy Transfer Along the Chlorophyll Networksupporting

confidence: 92%

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Quantum Chemical Description of Absorption Properties and Excited‐State Processes in Photosynthetic Systems

2011

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The theoretical description of the initial steps in photosynthesis has gained increasing importance over the past few years. This is caused by more and more structural data becoming available for light-harvesting complexes and reaction centers which form the basis for atomistic calculations and by the progress made in the development of first-principles methods for excited electronic states of large molecules. In this Review, we discuss the advantages and pitfalls of theoretical methods applicable to photosynthetic pigments. Besides methodological aspects of excited-state electronic-structure methods, studies on chlorophyll-type and carotenoid-like molecules are discussed. We also address the concepts of exciton coupling and excitation-energy transfer (EET) and compare the different theoretical methods for the calculation of EET coupling constants. Applications to photosynthetic light-harvesting complexes and reaction centers based on such models are also analyzed.

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Section: Energy Transfer Along the Chlorophyll Networksupporting

confidence: 92%

“…[397,401] According to refs. [397,401,406], this sink is localized in the Chl a trimer a610-a611-a612, mostly at the a610 site [397] (nomenclature according to ref. [391]).…”

Section: Energy Transfer Along the Chlorophyll Networkmentioning

confidence: 99%

Quantum Chemical Description of Absorption Properties and Excited‐State Processes in Photosynthetic Systems

2011

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“…The high-resolution experiments have been performed in fluorescence excitation mode with the apparatus described in 38 . Here we point out that the Spectra-Physics / Sirah Matisse-DS dye laser employed in this work is capable of seamless high-resolution scans of ~45 GHz, and can be stabilized to less than 30 MHz for hours in HGK measurements.…”

Section: Methodsmentioning

confidence: 99%

“…Several classes of SHB experiments probe different aspects of the protein energy landscapes. Experiments on hole evolution during the burning process, in particular hole growth kinetics (HGK) [15][16][17][18][19]37,38 measurements, probe the distribution of barriers in the excited electronic state of a pigment-protein system. It has been demonstrated that HGK results for a variety of glassy [15][16][17][18][19] and protein 37,38 systems are in good agreement with this model, employing Gaussian distributions of the tunneling parameter,  20,39 .…”

Section: Introductionmentioning

confidence: 99%

Spectral Hole Burning, Recovery, and Thermocycling in Chlorophyll–Protein Complexes: Distributions of Barriers on the Protein Energy Landscape

et al. 2012

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Chlorophyll-protein complexes are ideal model systems for protein energy landscape research. Here pigments, used in optical spectroscopy experiments as sensitive probes to local dynamics, are built into protein by Nature (in a large variety of local environments; without extraneous chemical manipulations or genetic engineering). Distributions of the tunneling parameter, λ, and/or protein energy landscape barrier heights, V, have been determined for (the lowest energy state of) the CP43 core antenna complex of photosystem II. We demonstrate that spectral hole burning (SHB) and hole recovery (HR) measurements are capable of delivering important information on protein energy landscape properties and spectral diffusion mechanism details. In particular, we show that tunneling rather than barrier hopping is responsible for both persistent SHB and subsequent HR at 5-12 K, which allows us to estimate the md(2) parameter of the tunneling entities as ~1.0 × 10(-46) kg·m(2). The subdistributions of λ actually contributing to the nonsaturated spectral holes (and affecting their recovery) differ from the respective full true distributions. In the case of the full λ-distribution being uniform (or the barrier height distribution ~1/√V, a model which has been widely employed in theories of amorphous solids at low temperatures and in HR analysis), the difference is qualitative, with λ subdistributions probed in the HR experiments being highly asymmetrical, and barrier V subdistributions deviating significantly from ~1/√V. Thus, the distribution of λ for the protein energy landscape tier directly probed by SHB is likely Gaussian and not uniform. Additionally, a Gaussian distribution of barriers, with parameters incompatible with those of the landscape tier directly probed by SHB, contributes to the thermocycling results.

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“…The EET rates shown in Figure 11 have been calculated based on the F€ orster mechanism using realistic spectral overlap integrals between Chl 37 and Chl 44. 51 The overlap integral dependence on the donorÀacceptor ZPL gap is calculated numerically based on the actual shape of the single-site spectra with the experimentally determined phonon sideband (PSB) and local mode parameters. All parameters in these calculations are the same as in our previous CP43 study, 6 except that to achieve good fits of various optical spectra for the CP43 0 ring we used the slightly larger S value of 0.6 as discussed above.…”

Section: Absorptionmentioning

confidence: 99%

Spectroscopic Study of the CP43′ Complex and the PSI–CP43′ Supercomplex of the Cyanobacterium Synechocystis PCC 6803

et al. 2011

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The PSI-CP43 supercomplex of the cyanobacterium Synechocystis PCC 6803, grown under iron-starvation conditions, consists of a trimeric core Photosystem I (PSI) complex and an outer ring of 18 CP43 light-harvesting complexes. We have investigated the electronic structure and excitation energy transfer (EET) pathways within the CP43 (also known as the isiA gene product) ring using low-temperature absorption, fluorescence, fluorescence excitation, and holeburning (HB) spectroscopies. Analysis of the absorption spectra of PSI, CP43, and PSI-CP43 complexes suggests that there are 13 chlorophylls (Chls) per CP43 monomer, i.e., a number that was observed in the CP43 complex of Photosystem II (PSII) (Umena, Y. et al. Nature 2011, 473, 55-60). This is in contrast with the recent modeling studies of Zhang, Y. et al. (Biochim. Biophys. Acta 2010, 1797, which suggested that IsiA likely contains 15 Chls. Modeling studies of various optical spectra of the CP43 ring using the uncorrelated EET model (Zazubovich, V.; Jankowiak, R. J. Lumin. 2007, 127, 245-250), suggest that CP43 monomers (in analogy to the CP43 complexes of PSII core) also possess two quasi-degenerate low-energy states, A and B. The site distribution functions of state A and B maxima/full width at half maximum (FWHM) are at 684 nm/180 cm , respectively. Our analysis shows that pigments mostly contributing to the lowest-energy A and B states must be located on the side of the CP43 complex facing the PSI core, a finding that contradicts the model of Zhang et al., but is in agreement with the model suggested by Nield et al. (Biochemistry 2003, 42, 3180-3188). We demonstrate that the A-A and B-B EET between different monomers is possible, though with a slower rate than intra-monomer A-B and/or B-A energy transfer.

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Parameters of the Protein Energy Landscapes of Several Light-Harvesting Complexes Probed via Spectral Hole Growth Kinetics Measurements

Cited by 16 publications

References 77 publications

Quantum Chemical Description of Absorption Properties and Excited‐State Processes in Photosynthetic Systems

Quantum Chemical Description of Absorption Properties and Excited‐State Processes in Photosynthetic Systems

Spectral Hole Burning, Recovery, and Thermocycling in Chlorophyll–Protein Complexes: Distributions of Barriers on the Protein Energy Landscape

Spectroscopic Study of the CP43′ Complex and the PSI–CP43′ Supercomplex of the Cyanobacterium Synechocystis PCC 6803

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