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Literatura académica sobre el tema "Monomeric antennae"

Autor: Grafiati

Publicado: 11 de marzo de 2023

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Artículos de revistas sobre el tema "Monomeric antennae"

Crepin, Aurélie, Erica Belgio, Barbora Šedivá, Eliška Kuthanová Trsková, Edel Cunill-Semanat y Radek Kaňa. "Size and Fluorescence Properties of Algal Photosynthetic Antenna Proteins Estimated by Microscopy". International Journal of Molecular Sciences 23, n.º 2 (11 de enero de 2022): 778. http://dx.doi.org/10.3390/ijms23020778.

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Antenna proteins play a major role in the regulation of light-harvesting in photosynthesis. However, less is known about a possible link between their sizes (oligomerization state) and fluorescence intensity (number of photons emitted). Here, we used a microscopy-based method, Fluorescence Correlation Spectroscopy (FCS), to analyze different antenna proteins at the particle level. The direct comparison indicated that Chromera Light Harvesting (CLH) antenna particles (isolated from Chromera velia) behaved as the monomeric Light Harvesting Complex II (LHCII) (from higher plants), in terms of their radius (based on the diffusion time) and fluorescence yields. FCS data thus indicated a monomeric oligomerization state of algal CLH antenna (at our experimental conditions) that was later confirmed also by biochemical experiments. Additionally, our data provide a proof of concept that the FCS method is well suited to measure proteins sizes (oligomerization state) and fluorescence intensities (photon counts) of antenna proteins per single particle (monomers and oligomers). We proved that antenna monomers (CLH and LHCIIm) are more “quenched” than the corresponding trimers. The FCS measurement thus represents a useful experimental approach that allows studying the role of antenna oligomerization in the mechanism of photoprotection.

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Wang, Quan y W. E. Moerner. "Dissecting pigment architecture of individual photosynthetic antenna complexes in solution". Proceedings of the National Academy of Sciences 112, n.º 45 (5 de octubre de 2015): 13880–85. http://dx.doi.org/10.1073/pnas.1514027112.

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Oligomerization plays a critical role in shaping the light-harvesting properties of many photosynthetic pigment−protein complexes, but a detailed understanding of this process at the level of individual pigments is still lacking. To study the effects of oligomerization, we designed a single-molecule approach to probe the photophysical properties of individual pigment sites as a function of protein assembly state. Our method, based on the principles of anti-Brownian electrokinetic trapping of single fluorescent proteins, step-wise photobleaching, and multiparameter spectroscopy, allows pigment-specific spectroscopic information on single multipigment antennae to be recorded in a nonperturbative aqueous environment with unprecedented detail. We focus on the monomer-to-trimer transformation of allophycocyanin (APC), an important antenna protein in cyanobacteria. Our data reveal that the two chemically identical pigments in APC have different roles. One (α) is the functional pigment that red-shifts its spectral properties upon trimer formation, whereas the other (β) is a “protective” pigment that persistently quenches the excited state of α in the prefunctional, monomer state of the protein. These results show how subtleties in pigment organization give rise to functionally important aspects of energy transfer and photoprotection in antenna complexes. The method developed here should find immediate application in understanding the emergent properties of other natural and artificial light-harvesting systems.

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Wang, Zhimo, Bingbing Suo, Shiwei Yin y Wenli Zou. "Quantum Chemical Simulation of the Qy Absorption Spectrum of Zn Chlorin Aggregates for Artificial Photosynthesis". Molecules 26, n.º 4 (19 de febrero de 2021): 1086. http://dx.doi.org/10.3390/molecules26041086.

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Zn chlorin (Znchl) is easy to synthesize and has similar optical properties to those of bacteriochlorophyll c in the nature, which is expected to be used as a light-harvesting antenna system in artificial photosynthesis. In order to further explore the optical characteristics of Znchl, various sizes of a parallel layered Znchl-aggregate model and the THF-Znchl explicit solvent monomer model were constructed in this study, and their Qy excited state properties were simulated by using time-dependent density functional theory (TDDFT) and exciton theory. For the Znchl monomer, with a combination of the explicit solvent model and the implicit solvation model based on density (SMD), the calculated Qy excitation energy agreed very well with the experimental one. The Znchl aggregates may be simplified to a Zn36 model to reproduce the experimental Qy absorption spectrum by the Förster coupling theory. The proposed Znchl aggregate model provides a good foundation for the future exploration of other properties of Znchl and simulations of artificial light-harvesting antennas. The results also indicate that J-aggregrates along z-direction, due to intermolecular coordination bonds, are the dominant factor in extending the Qy band of Znchl into the near infrared region.

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Miloslavina, Yuliya, Silvia de Bianchi, Luca Dall'Osto, Roberto Bassi y Alfred R. Holzwarth. "Quenching in Arabidopsis thaliana Mutants Lacking Monomeric Antenna Proteins of Photosystem II". Journal of Biological Chemistry 286, n.º 42 (15 de agosto de 2011): 36830–40. http://dx.doi.org/10.1074/jbc.m111.273227.

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Pishchalnikov, Roman, Vladimir Shubin y Andrei Razjivin. "Single Molecule Fluorescence Spectroscopy of PSI Trimers from Arthrospira platensis: A Computational Approach". Molecules 24, n.º 4 (25 de febrero de 2019): 822. http://dx.doi.org/10.3390/molecules24040822.

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Based on single molecule spectroscopy analysis and our preliminary theoretical studies, the linear and fluorescence spectra of the PSI trimer from Arthrospira platensis with different realizations of the static disorder were modeled at cryogenic temperature. Considering the previously calculated spectral density of chlorophyll, an exciton model for the PSI monomer and trimer including the red antenna states was developed taking into account the supposed similarity of PSI antenna structures from Thermosynechococcus e., Synechocystis sp. PCC6803, and Arthrospira platensis. The red Chls in the PSI monomer were assumed to be in the nearest proximity of the reaction center. The PSI trimer model allowed the simulation of experimentally measured zero phonon line distribution of the red states considering a weak electron-phonon coupling for the antenna exciton states. However, the broad absorption and fluorescence spectra of an individual emitter at 760 nm were calculated by adjusting the Huang-Rhys factors of the chlorophyll lower phonon modes assuming strong electron-phonon coupling.

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Ballottari, Matteo, Milena Mozzo, Julien Girardon, Rainer Hienerwadel y Roberto Bassi. "Chlorophyll Triplet Quenching and Photoprotection in the Higher Plant Monomeric Antenna Protein Lhcb5". Journal of Physical Chemistry B 117, n.º 38 (8 de julio de 2013): 11337–48. http://dx.doi.org/10.1021/jp402977y.

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KUREISHI, YASUHIKO y HITOSHI TAMIAKI. "Synthesis and Self-aggregation of Zinc 20-Halogenochlorins as a Model for Bacteriochlorophylls c/d". Journal of Porphyrins and Phthalocyanines 02, n.º 02 (marzo de 1998): 159–69. http://dx.doi.org/10.1002/(sici)1099-1409(199803/04)2:2<159::aid-jpp62>3.0.co;2-q.

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Zinc 20-halogenochlorins 2(20- F ), 3(20- Cl ) and 4(20- Br ) were synthesized by halogenation of a chlorophyll a derivative at the 20-position as a model for bacteriochlorophyll ( BChl )c, which possesses a methyl group at the 20-position and 20-unsubstituted BChl d. Visible spectra in a polar tetrahydrofuran ( THF ) solution showed that 2-4 were monomeric and the planarity of the chlorin ring, was distorted with increasing bulkiness of the 20-substituent. Visible, circular dichroism and IR spectra revealed that 2-4 self-aggregated to form oligomers similarly with 20-unsubstituted 1 and BChls c/d in the heterogeneous thin film as well as in homogeneous non-polar solvents (1% (v/v) THF-hexane). Therefore, the in vitro self-aggregates of 2-4 are good structural models for in vivo BChls c/d self-aggregates, the main antenna components of photosynthetic green bacteria. Fluorescence spectra showed that monomeric 3 and 4 were less emissive than 1 and 2 due to the heavy atom effect which could not be observed in the oligomeric species, indicating that the in vitro aggregates should be promising as functional (light-harvesting) models.

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Meador, Michael A., Mary Ann Meador, Daniel S. Tyson y Faysal Ilhan. "Use of Diels-Alder Cyclopolymerizations in the Photocuring of Polymers". High Performance Polymers 19, n.º 5-6 (octubre de 2007): 665–83. http://dx.doi.org/10.1177/0954008307081210.

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Radiation curable polymers are needed for use in space rigidizable inflatable structures (antenna supports, habitats, rovers) for future NASA missions. One approach developed at NASA Glenn utilizes the Diels-Alder trapping of bisdienes (o-xylylenols) generated by the photolysis of o-methylphenyl ketones with bisdienophiles (bismaleimides and bisacrylates). A variety of polyimides and polyesters have been prepared with this chemistry and their properties evaluated. The glass transition temperatures of these resins varied from –27 to over 300°C depending upon monomer structures. Onsets of decomposition, measured by thermogravimetric analysis in air, were in the neighborhood of 300°C and did not vary much with monomer structure. Some monomer systems are liquids at room temperature and have the potential for use in solvent-free UV-cured coatings.

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Squires, Allison H. y W. E. Moerner. "Direct single-molecule measurements of phycocyanobilin photophysics in monomeric C-phycocyanin". Proceedings of the National Academy of Sciences 114, n.º 37 (28 de agosto de 2017): 9779–84. http://dx.doi.org/10.1073/pnas.1705435114.

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Phycobilisomes are highly organized pigment–protein antenna complexes found in the photosynthetic apparatus of cyanobacteria and rhodophyta that harvest solar energy and transport it to the reaction center. A detailed bottom-up model of pigment organization and energy transfer in phycobilisomes is essential to understanding photosynthesis in these organisms and informing rational design of artificial light-harvesting systems. In particular, heterogeneous photophysical behaviors of these proteins, which cannot be predicted de novo, may play an essential role in rapid light adaptation and photoprotection. Furthermore, the delicate architecture of these pigment–protein scaffolds sensitizes them to external perturbations, for example, surface attachment, which can be avoided by study in free solution or in vivo. Here, we present single-molecule characterization of C-phycocyanin (C-PC), a three-pigment biliprotein that self-assembles to form the midantenna rods of cyanobacterial phycobilisomes. Using the Anti-Brownian Electrokinetic (ABEL) trap to counteract Brownian motion of single particles in real time, we directly monitor the changing photophysical states of individual C-PC monomers from Spirulina platensis in free solution by simultaneous readout of their brightness, fluorescence anisotropy, fluorescence lifetime, and emission spectra. These include single-chromophore emission states for each of the three covalently bound phycocyanobilins, providing direct measurements of the spectra and photophysics of these chemically identical molecules in their native protein environment. We further show that a simple Förster resonant energy transfer (FRET) network model accurately predicts the observed photophysical states of C-PC and suggests highly variable quenching behavior of one of the chromophores, which should inform future studies of higher-order complexes.

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Pi, Xiong, Songhao Zhao, Wenda Wang, Desheng Liu, Caizhe Xu, Guangye Han, Tingyun Kuang, Sen-Fang Sui y Jian-Ren Shen. "The pigment-protein network of a diatom photosystem II–light-harvesting antenna supercomplex". Science 365, n.º 6452 (1 de agosto de 2019): eaax4406. http://dx.doi.org/10.1126/science.aax4406.

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Diatoms play important roles in global primary productivity and biogeochemical cycling of carbon, in part owing to the ability of their photosynthetic apparatus to adapt to rapidly changing light intensity. We report a cryo–electron microscopy structure of the photosystem II (PSII)–fucoxanthin (Fx) chlorophyll (Chl) a/c binding protein (FCPII) supercomplex from the centric diatom Chaetoceros gracilis. The supercomplex comprises two protomers, each with two tetrameric and three monomeric FCPIIs around a PSII core that contains five extrinsic oxygen-evolving proteins at the lumenal surface. The structure reveals the arrangement of a huge pigment network that contributes to efficient light energy harvesting, transfer, and dissipation processes in the diatoms.

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Actas de conferencias sobre el tema "Monomeric antennae"

Savikhin, S. y W. S. Struve. "Optical coherences in light-harvesting chlorosomes from green photosynthetic bacteria". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/up.1996.tue.21.

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Chlorosomes are light-harvesting assemblies that are found in green photosynthetic bacteria [1]. The principal antenna in a chlorosome consists of ~104 bacteriochlorophyll (BChl) c, d, or e pigments, which give rise to a broad Qy electronic absorption band centered at ~ 740 nm. Excitations in the BChl c/d/e antenna are transferred to a lower- energy BChl a antenna absorbing at ~795 nm, prior to trapping at the reaction centers [2]. BChl c/d/e antennae in chlorosomes appear to be pigment oligomers whose structure is determined by pigment-pigment rather than pigment-protein interactions, because spectroscopically similar BChl aggregates self-assemble spontaneously from the pigment monomers in solution [3]. The internal energy transfer kinetics of reconstituted BChl c aggregates from the green bacteria Chloroflexus aurantiacus and Chlorobium tepidum closely resemble those found in the BChl c antennae of the intact chlorosomes [4].

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Sharkov, A. V., E. V. Khoroshilov, I. V. Kryukov, P. G. Kryukov, T. Gillbro, R. Fischer y H. Scheer. "Femtosecond Energy Transfer Processes in C-Phycocyanin and Allophycocyanin Trimers". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/up.1992.mc2.

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Allophycocyanin and C-Phycocyanin are photosynthetic antenna pigments of the light-harvesting complexes (phycobilisomes) of blue greem bacteria and red algae. Important questions under investigations are related to transfer of excitation energy between nearby chromophores in aggregates (mainly trimers) of C-PC and APC. One has, for instance, to discuss different models for the energy transfer including Förster and excitoic mechanisms. APC monomer contains two chromophores, namely α84 and β84 ones. The optical spectrum of the APC monomer has the maximum at 620 nm. In contrast to this, the spectrum of APC trimer has a sharp peak at 650 nm and a shoulder about 620 nm. In contrast to APC, C-phycocyanin monomer contains three chromophores, α84, β84 and β155, and absorption spectrum of the C-PC trimer with maximum near 620 nm shows close resemblance to that of the C-PC monomers.

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Savikhir, S., Y. Zhu, S. Lin, R. E. Blankenship y W. S. Struve. "Femtosecond energy transfer and coherent oscillations in BChl c light-harvesting antennae of chlorosomes from the green photosynthetic bacterium Chloroflexus aurantiacus". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/up.1994.tub.3.

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Chlorosomes are the principal light-harvesting bodies in green photosynthetic bacteria. These 100×30×12 nm ellipsoidal bodies contain ~104 bacteriochlorophyll (BChl) c chromophores, as well as a BChl a pigment-protein complex that forms an interfacial baseplate between the chlorosome and the cytoplasmic membrane. The BChl c pigments in chlorosomes are organized into large oligomers, whose electronic and vibrational spectroscopy is remarkably similar to that of BChl c aggregates that form spontaneously from BChl c monomers in solution. This unique self-aggregating property has attracted wide attention because of its potential applications in artificial photosynthesis. The BChl c and BChl a antennae of chlorosomes from the green bacterium Chloroflexus aurantiacus exhibit broad Qy (S1←S0) electronic absorption bands centered at ~740 and ~790 nm, respectively. Downhill BChl c → BChl a energy transfer occurs with ~10 ps kinetics in isolated chlorosomes [1,2]. In this work, we have focussed on the femtosecond internal energy transfer events within the BChl c antenna. It is currently believed [3] that this 740 nm antenna comprises several distinct BChl c spectral forms (c727, c744, c766 etc.) Equilibration among chlorophyll and bacteriochlorophyll spectral forms requires several hundred fs in most pigment-protein antenna complexes that have been studied to date [4].

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Matro, Alexander y Jeffrey A. Cina. "Time-Resolved Fluorescence Anisotropy in Chromophore Pairs". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/up.1994.wc.25.

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Electronic excitation transfer has been the subject of numerous experimental and theoretical studies. Recent experimental measurements of time-resolved fluorescence and pump-probe anisotropy have revealed sub-picosecond excitation transfer processes, seen as decays in the anisotropy. The experiments of Xie et al.[1] on Allophycocyanin (APC) and C-Phycocyanin (C-PC) isolated from photosynthetic antenna systems in cyanobacteria, measuring time-resolved fluorescence anisotropy with ~ 100 fs time resolution, found that the ultrafast decay component in the anisotropy showed a strong dependence on excitation/detection wavelength. The sub-picosecond decay anisotropy decay was seen in trimers of APC and C-PC and not in monomers, and, therefore, this fast decay has been attributed to pairwise excitation transfer among chromophores on different monomers of APC and C-PC.

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