Single-protein study of photoresistance of pigment–protein complex in lipid bilayer

Uchiyama, Daisuke; Hoshino, Hiromitsu; Otomo, Kohei; Kato, Takuya; Onda, Kenichi; Watanabe, Akira; Oikawa, Hiroyuki; Fujiyoshi, Satoru; Matsushita, Michio M.; Nango, Mamoru; Watanabe, Natsuko; Sumino, Ayumi; Dewa, Takehisa

doi:10.1016/j.cplett.2011.06.019

Cited by 5 publications

(8 citation statements)

References 19 publications

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“…From those spectra we determined the spectral peak positions of the absorption bands, and assigned these bands from red to blue to the k ¼ 0, the k ¼ 51, and to higher exciton states, respectively. To check whether the restriction to those 28 complexes could lead to conclusions about the excitonic energy manifold that might not be representative for the ensemble of LH2 complexes, we compared the energetic separations between the spectral peak positions of the exciton states with those obtained in previous work (30,59,(62)(63)(64), see Table 1.…”

Section: The Influence Of Spectral Diffusionmentioning

confidence: 99%

Single-Molecule Spectroscopy Unmasks the Lowest Exciton State of the B850 Assembly in LH2 from Rps. acidophila

Kunz

Timpmann

Southall

et al. 2014

Biophysical Journal

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We have recorded fluorescence-excitation and emission spectra from single LH2 complexes from Rhodopseudomonas (Rps.) acidophila. Both types of spectra show strong temporal spectral fluctuations that can be visualized as spectral diffusion plots. Comparison of the excitation and emission spectra reveals that for most of the complexes the lowest exciton transition is not observable in the excitation spectra due to the cutoff of the detection filter characteristics. However, from the spectral diffusion plots we have the full spectral and temporal information at hand and can select those complexes for which the excitation spectra are complete. Correlating the red most spectral feature of the excitation spectrum with the blue most spectral feature of the emission spectrum allows an unambiguous assignment of the lowest exciton state. Hence, application of fluorescence-excitation and emission spectroscopy on the same individual LH2 complex allows us to decipher spectral subtleties that are usually hidden in traditional ensemble spectroscopy.

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Section: The Influence Of Spectral Diffusionmentioning

confidence: 99%

Single-Molecule Spectroscopy Unmasks the Lowest Exciton State of the B850 Assembly in LH2 from Rps. acidophila

Kunz

Timpmann

Southall

et al. 2014

Biophysical Journal

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“…This has been made possible by considerable progress in the development of experimental techniques such as nonlinear 2D electronic spectroscopy (2DES) and broad-band pump–probe spectroscopy − that can probe the average ultrafast dynamics of an initially prepared ensemble of electronically and vibrationally excited superposition states. − These experimental techniques can now explore the fundamental quantum dynamics responsible for the core steps of these processes and have revealed a remarkable richness in this underlying early time evolution. − Understanding how nature optimizes the short time nonequilibrium dissipation and dephasing processes to control the ultimate charge separation efficiency is a key design concept that these experiments can now begin to address, but generally only in the inhomogeneously broadened, ensemble-averaged limit. Detailed knowledge of the underlying molecular design criteria that make these natural systems so efficient will be transformative, potentially enabling significant advances in solar energy technologies. − Unfortunately, exploring how particular instantaneous inherent structures − sampled by fluctuations might do much better (or much worse) than the average as far as efficiency is concerned is not possible with these current experimental techniques …”

Section: Introductionmentioning

confidence: 99%

First-Principles Models for Biological Light-Harvesting: Phycobiliprotein Complexes from Cryptophyte Algae

2017

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There have been numerous efforts, both experimental and theoretical, that have attempted to parametrize model Hamiltonians to describe excited state energy transfer in photosynthetic light harvesting systems. The Frenkel exciton model, with its set of electronically coupled two level chromophores that are each linearly coupled to dissipative baths of harmonic oscillators, has become the workhorse of this field. The challenges to parametrizing such Hamiltonians have been their uniqueness, and physical interpretation. Here we present a computational approach that uses accurate first-principles electronic structure methods to compute unique model parameters for a collection of local minima that are sampled with molecular dynamics and QM geometry optimization enabling the construction of an ensemble of local models that captures fluctuations as these systems move between local basins of inherent structure. The accuracy, robustness, and reliability of the approach is demonstrated in an application to the phycobiliprotein light harvesting complexes from cryptophyte algae. Our computed Hamiltonian ensemble provides a first-principles description of inhomogeneous broadening processes, and a standard approximate non-Markovian reduced density matrix dynamics description is used to estimate lifetime broadening contributions to the spectral line shape arising from electronic-vibrational coupling. Despite the overbroadening arising from this approximate line shape theory, we demonstrate that our model Hamiltonian ensemble approach is able to provide a reliable fully first-principles method for computation of spectra and can distinguish the influence of different chromophore protonation states in experimental results. A key feature in the dynamics of these systems is the excitation of intrachromophore vibrations upon electronic excitation and energy transfer. We demonstrate that the Hamiltonian ensemble approach provides a reliable first-principles description of these contributions that have been detailed in recent broad-band pump-probe and two-dimensional electronic spectroscopy experiments.

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“…These perturbations have been shown to alter other emissive properties. For example, the photobleaching quantum yield of LH2 increases in detergent micelles relative to a phosopholipid bilayer environment composed of dimyristoylphosphatidylcholine (DMPC) . Conversely, LH2 complexes in a bilayer of dioleoylphosphatidylcholine (DOPC) showed almost the same spectral properties for the B850 band as that in a micelle .…”

Section: Energetic Heterogeneity: Characterization Of the Excited Sta...mentioning

confidence: 99%

“…Conversely, LH2 complexes in a bilayer of dioleoylphosphatidylcholine (DOPC) showed almost the same spectral properties for the B850 band as that in a micelle . This discrepancy was thought to originate from the difference between the phase-transition temperatures of the two phospholipid bilayers . Additionally, the use of different detergents, n -octyl-β- d -glucopyranoside (OG) and lauryldimethylamine N -oxide (LDAO), may create different micelles that also contribute to the conflicting results.…”

Section: Energetic Heterogeneity: Characterization Of the Excited Sta...mentioning

confidence: 99%

“…For example, the photobleaching quantum yield of LH2 increases in detergent micelles relative to a phosopholipid bilayer environment composed of dimyristoylphosphatidylcholine (DMPC). 261 Conversely, LH2 complexes in a bilayer of dioleoylphosphatidylcholine (DOPC) showed almost the same spectral properties for the B850 band as that in a micelle. 13 This discrepancy was thought to originate from the difference between the phase-transition temperatures of the two phospholipid bilayers.…”

Section: Chemical Reviewsmentioning

confidence: 99%

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Single-Molecule Fluorescence Spectroscopy of Photosynthetic Systems

2017

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Photosynthesis begins when a network of pigment-protein complexes captures solar energy and transports it to the reaction center, where charge separation occurs. When necessary (under low light conditions), photosynthetic organisms perform this energy transport and charge separation with near unity quantum efficiency. Remarkably, this high efficiency is maintained under physiological conditions, which include thermal fluctuations of the pigment-protein complexes and changing local environments. These conditions introduce multiple types of heterogeneity in the pigment-protein complexes, including structural heterogeneity, energetic heterogeneity, and functional heterogeneity. Understanding how photosynthetic light-harvesting functions in the face of these fluctuations requires understanding this heterogeneity, which, in turn, requires characterization of individual pigment-protein complexes. Single-molecule spectroscopy has the power to probe individual complexes. In this review, we present an overview of the common techniques for single-molecule fluorescence spectroscopy applied to photosynthetic systems and describe selected experiments on these systems. We discuss how these experiments provide a new understanding of the impact of heterogeneity on light harvesting and thus how these systems are optimized to capture sunlight under physiological conditions.

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Single-protein study of photoresistance of pigment–protein complex in lipid bilayer

Cited by 5 publications

References 19 publications

Single-Molecule Spectroscopy Unmasks the Lowest Exciton State of the B850 Assembly in LH2 from Rps. acidophila

Single-Molecule Spectroscopy Unmasks the Lowest Exciton State of the B850 Assembly in LH2 from Rps. acidophila

First-Principles Models for Biological Light-Harvesting: Phycobiliprotein Complexes from Cryptophyte Algae

Single-Molecule Fluorescence Spectroscopy of Photosynthetic Systems

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