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Jan Hála - One of the best experts on this subject based on the ideXlab platform.
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Spectral hole burning study of photosynthetic Antenna Pigment-protein complexes
Journal of Molecular Structure, 1993Co-Authors: Martin Vacha, F. Adamec, M. Ambrož, Juraj Dian, Jakub Pšenčík, Jan HálaAbstract:Abstract Results of persistent spectral hole burning in fluorescence spectra of photosystem II core Antenna complexes CP 43 and CP 47 are presented. The holewidths (extrapolated to zero burning fluence) yield the excited state population decay times T 1 which are influenced by fast energy transfer within the Antenna complexes. The obtained T 1 values range between 6.6 and 10 ps. The holewidths are independent on temperature within the studied temperature interval 1.5-4.2 K. The observed phenomenon of laser-induced hole filling in the spectra of CP 43 is explained in terms of energy transfer within the CP 43 Pigment-protein complex.
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spectral properties of Antenna Pigment protein complexes studied by hole burning spectroscopy
Journal of Luminescence, 1992Co-Authors: Martin Vacha, F. Adamec, M. Ambrož, Juraj Dian, Jan HálaAbstract:Abstract Persistent spectral hole-burning fluorescence spectra of photosystem II core Antenna at 4.2 were measured. The obtained hole widths were interpreted in terms of fast excited energy transfer within Pigment-protein complexes. The energy transfer efficiency, the inhomogeneous distribution function and hole-burning mechanism are discussed with respect to the role of the surrounding protein environment (polymer, glass). The observed light induced hole filling is also interpreted as a result of efficient energy transfer.
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Spectral properties of Antenna Pigment—protein complexes studied by hole-burning spectroscopy
Journal of Luminescence, 1992Co-Authors: Martin Vacha, F. Adamec, M. Ambrož, Juraj Dian, Jan HálaAbstract:Abstract Persistent spectral hole-burning fluorescence spectra of photosystem II core Antenna at 4.2 were measured. The obtained hole widths were interpreted in terms of fast excited energy transfer within Pigment-protein complexes. The energy transfer efficiency, the inhomogeneous distribution function and hole-burning mechanism are discussed with respect to the role of the surrounding protein environment (polymer, glass). The observed light induced hole filling is also interpreted as a result of efficient energy transfer.
Zbigniew Krupa - One of the best experts on this subject based on the ideXlab platform.
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Temperature-induced isomerization of violaxanthin in organic solvents and in light-harvesting complex II.
Journal of photochemistry and photobiology. B Biology, 2005Co-Authors: Dariusz M. Niedzwiedzki, Zbigniew Krupa, Wiesław I. GruszeckiAbstract:Abstract Three main xanthophyll Pigments are bound to the major photosynthetic Pigment-protein complex of Photosystem II (LHCII): lutein, neoxanthin and violaxanthin. Chromatographic analysis of the xanthophyll fraction of LHCII reveals that lutein appears mainly in the all-trans conformation, neoxanthin in the 9′-cis conformation and major fraction of violaxanthin in the all-trans conformation. Nevertheless, a small fraction of violaxanthin appears always in a cis conformation: 9-cis and 13-cis (approximately 4% and 2% in the darkness, respectively). Illumination of the isolated complex (5 min, 445 nm, 250 μmol m−2 s−1) results in the substantial increase in the concentration of the cis steric conformers of violaxanthin: up to 6% of 9-cis and 4% of 13-cis. Similar effect can be obtained by dark incubation of the same preparation for 30 min at 60 °C. Heating-induced isomerization of the all-trans violaxanthin can also be obtained in the organic solvent system but the formation of the 9-cis stereoisomer has not been observed under such conditions. The fact that the appearance of the 9-cis form of violaxanthin is specific for the protein environment suggests that violaxanthin may replace neoxanthin in LHCII in the N1 xanthophyll binding pocket and that the protein stabilizes this particular conformation. The analysis of the electronic absorption spectra of LHCII and the FTIR spectra of the protein in the Amid I band spectral region indicates that violaxanthin isomerization is associated with the disaggregation of the complex. It is postulated that this reorganization of LHCII provides conditions for desorption of violaxanthin from the Pigment protein complexes, its diffusion within the thylakoid membrane and therefore, availability to the enzymatic deepoxidation within the xanthophyll cycle. It is also possible that violaxanthin isomerization plays the role of a security valve, by consuming an energy of excessive excitations in the Antenna Pigment network (in particular, exchanged at the triplet state levels).
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spectral analysis of Pigment photobleaching in photosynthetic Antenna complex lhciib
Journal of Photochemistry and Photobiology B-biology, 2003Co-Authors: Dorota Olszowka, Zbigniew Krupa, Waldemar Maksymiec, Stanislaw KrawczykAbstract:Abstract Light-induced photooxidation of chlorophyll (Chl) a, b and xanthophylls was investigated in LHCIIb, the Antenna Pigment–protein complex of photosystem II. Absorption difference spectra at normal and low temperatures show initially (at less than 25% Chl a decay) a selective bleaching of a red-shifted Chl b with absorption bands at 487 and 655 nm, Chl b (460/650 nm) and Chl a (433/670 nm), which changes to a less selective photooxidation pattern at deeper bleaching stages. Difference absorption spectra and HPLC analyses indicate different photooxidation rates of Pigments in the order neoxanthin>Chl a>lutein≈Chl b. Despite significant Pigment loss as monitored with absorption spectra, CD spectra indicate an essentially complete persistence of the protein secondary structure. Fluorescence excitation spectra suggest the conversion of a small fraction of Chl a into pheophytin a which acts as a fluorescence quencher, possibly through temporary charge separation process. The strong features in the electroabsorption (Stark effect) spectra due to chlorophyll b at 655 nm and a xanthophyll at 510 nm, and the spectral changes mentioned above are assigned to Chl molecules located at several binding sites in LHCIIb protein and are discussed in the context of spatial configuration and interactions of Pigment molecules.
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Cis-trans-isomerization of violaxanthin in LHC II: violaxanthin isomerization cycle within the violaxanthin cycle
Biochimica et Biophysica Acta, 1997Co-Authors: Wiesław I. Gruszecki, Magdalena Matuła, Naomi Ko-chi, Yasushi Koyama, Zbigniew KrupaAbstract:Chlorophyll fluorescence excitation and emission spectroscopy, electron absorption spectroscopy and resonance Raman spectrometry of light-harvesting Pigment-protein complex of Photosystem II (LHC II), isolated and incorporated to liposomes, indicate that a carotenoid Pigment violaxanthin is present in this complex in conformation 15, 15′-cis. Light-induced cis-trans-isomerization of violaxanthin is combined with an energetic uncoupling of this Antenna Pigment from chlorophyll and is interpreted in terms of detachment of this carotenoid from protein — the process of making violaxanthin available for de-epoxidation within the lipid phase of the thylakoid membrane. It is also demonstrated that the process of heat-induced detachment of violaxanthin from LHC II is not combined with a cis-trans- isomerization.
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Stark spectra of chlorophylls and carotenoids in Antenna Pigment-proteins LHC-II and CP-II
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 1993Co-Authors: Krawczyk, Zbigniew Krupa, Waldemar MaksymiecAbstract:Abstract The band structure of low-temperature absorption and Stark spectra of light-harvesting chlorophyll a/b protein complexes LHC-II and CP-II is analysed. In the red spectral region, the Stark spectrum serves as an independent experimental reference allowing for the resolution of eight bands at 639, 642–3, 649, 656, 662, 665 671 and 678 nm, consistently with the gaussian deconvolution of the absorption spectrum. Different parts of the Stark spectrum are fitted with combinations of the derivatives of either the total absorption spectrum or of individual gaussian components. Two electronic transitions at 671 nm and 678 nm and two others at 639 nm and 642–3 nm are found to excite, respectively, localized chlorophyll a and chlorophyll b states. Increased changes in permanent dipole moment, Δμ ≅ 2.2 Debye units, corresponding to the transitions at 656 nm and at 665 nm, and an increase in polarizability ≅ 70 A3 corresponding to the first of them indicate that these transitions originate from strong exciton coupling. In the violet, the Stark spectra are dominated by the contribution from xanthophylls. A value of Δμ ≥ 10 D was estimated for xanthophyll bands at 484 nm and at 511–513 nm. The mechanism of the Stark effect in xanthophylls is briefly discussed.
Martin Vacha - One of the best experts on this subject based on the ideXlab platform.
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Spectral hole burning study of photosynthetic Antenna Pigment-protein complexes
Journal of Molecular Structure, 1993Co-Authors: Martin Vacha, F. Adamec, M. Ambrož, Juraj Dian, Jakub Pšenčík, Jan HálaAbstract:Abstract Results of persistent spectral hole burning in fluorescence spectra of photosystem II core Antenna complexes CP 43 and CP 47 are presented. The holewidths (extrapolated to zero burning fluence) yield the excited state population decay times T 1 which are influenced by fast energy transfer within the Antenna complexes. The obtained T 1 values range between 6.6 and 10 ps. The holewidths are independent on temperature within the studied temperature interval 1.5-4.2 K. The observed phenomenon of laser-induced hole filling in the spectra of CP 43 is explained in terms of energy transfer within the CP 43 Pigment-protein complex.
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spectral properties of Antenna Pigment protein complexes studied by hole burning spectroscopy
Journal of Luminescence, 1992Co-Authors: Martin Vacha, F. Adamec, M. Ambrož, Juraj Dian, Jan HálaAbstract:Abstract Persistent spectral hole-burning fluorescence spectra of photosystem II core Antenna at 4.2 were measured. The obtained hole widths were interpreted in terms of fast excited energy transfer within Pigment-protein complexes. The energy transfer efficiency, the inhomogeneous distribution function and hole-burning mechanism are discussed with respect to the role of the surrounding protein environment (polymer, glass). The observed light induced hole filling is also interpreted as a result of efficient energy transfer.
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Spectral properties of Antenna Pigment—protein complexes studied by hole-burning spectroscopy
Journal of Luminescence, 1992Co-Authors: Martin Vacha, F. Adamec, M. Ambrož, Juraj Dian, Jan HálaAbstract:Abstract Persistent spectral hole-burning fluorescence spectra of photosystem II core Antenna at 4.2 were measured. The obtained hole widths were interpreted in terms of fast excited energy transfer within Pigment-protein complexes. The energy transfer efficiency, the inhomogeneous distribution function and hole-burning mechanism are discussed with respect to the role of the surrounding protein environment (polymer, glass). The observed light induced hole filling is also interpreted as a result of efficient energy transfer.
Richard J. Cogdell - One of the best experts on this subject based on the ideXlab platform.
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photoprotective mechanisms in the core lh1 Antenna Pigment protein complex from the purple photosynthetic bacterium rhodospirillum rubrum
Journal of Photochemistry and Photobiology A-chemistry, 2020Co-Authors: Chiasa Uragami, Richard J. Cogdell, Hiroki Sato, Nao Yukihira, Masazumi Fujiwara, Daisuke Kosumi, Alastair T Gardiner, Hideki HashimotoAbstract:Abstract Time-resolved absorption spectra from the femtoscecond to sub-millisecond time regimes were recorded in order to eluciate the photoprotective mechanisms of carotenoid (spirilloxanthin) in core LH1 light-harvesting Pigment-protein complexes from a purple photosynthetic bacterium, Rhodospirillum (Rsp.) rubrum. Carotenoids can prevent the production of singlet oxygen by rapidly quenching the Bchl a triplet state. Through this triplet-triplet energy-transfer reaction the carotenoid is believed to protect the biological system from exposure to excess light. We set out to investigate this paricular function in the purple bacterium, Rsp. rubrum strain S1. We also investigated Rsp. rubrum strain G9+, which is the carotenoidless mutant of Rsp. rubrum, to make sure that the carotenoid is truly playing this important role. As a result, we could demonstrate that strain S1 realizes nearly 100% excitation energy transfer from triplet Bchl a to carotenoid. In addition, we found another major excited state deactivation channel of carotenoids, which takes away excess energy directly from the singlet excited state of Bchl a and so prevents the production of triplet excited Bchl a.
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Spectral heterogeneity and carotenoid-to-bacteriochlorophyll energy transfer in LH2 light-harvesting complexes from Allochromatium vinosum
Photosynthesis Research, 2016Co-Authors: Nikki M. Magdaong, Dariusz M. Niedzwiedzki, Richard J. Cogdell, Amy M. Lafountain, Kirsty Hacking, George N. Gibson, Harry A FrankAbstract:Photosynthetic organisms produce a vast array of spectral forms of Antenna Pigment-protein complexes to harvest solar energy and also to adapt to growth under the variable environmental conditions of light intensity, temperature, and nutrient availability. This behavior is exemplified by Allochromatium ( Alc. ) vinosum , a photosynthetic purple sulfur bacterium that produces different types of LH2 light-harvesting complexes in response to variations in growth conditions. In the present work, three different spectral forms of LH2 from Alc. vinosum , B800-820, B800-840, and B800-850, were isolated, purified, and examined using steady-state absorption and fluorescence spectroscopy, and ultrafast time-resolved absorption spectroscopy. The Pigment composition of the LH2 complexes was analyzed by high-performance liquid chromatography, and all were found to contain five carotenoids: lycopene, anhydrorhodovibrin, spirilloxanthin, rhodopin, and rhodovibrin. Spectral reconstructions of the absorption and fluorescence excitation spectra based on the Pigment composition revealed significantly more spectral heterogeneity in these systems compared to LH2 complexes isolated from other species of purple bacteria. The data also revealed the individual carotenoid-to-bacteriochlorophyll energy transfer efficiencies which were correlated with the kinetic data from the ultrafast transient absorption spectroscopic experiments. This series of LH2 complexes allows a systematic exploration of the factors that determine the spectral properties of the bound Pigments and control the rate and efficiency of carotenoid-to-bacteriochlorophyll energy transfer.
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Pigment Pigment interactions and energy transfer in the Antenna complex of the photosynthetic bacterium rhodopseudomonas acidophila
Structure, 1996Co-Authors: Andrew A Freer, Richard J. Cogdell, Steve M Prince, Ken Sauer, M Z Papiz, Anna Hawthornthwaite Lawless, Gerry Mcdermott, Neil W IsaacsAbstract:Abstract Background: Photosynthesis starts with the absorption of solar radiation by Antenna Pigment molecules. In purple bacteria these chromophores, (bacteriochlorophyll a and carotenoid) are embedded in the membrane; they are non-covalently bound to apoproteins which have the ability to modulate the chromophores' absorbing characteristics. The first structure of the bacterial Antenna complex from Rhodopseudomonas acidophila , strain 10050, shows a ring of nonameric symmetry. Two concentric cylinders of apoproteins enclose the Pigment molecules. The current resolution of the structure, to 2.5 a, allows us to begin to explore the mechanism of energy transfer among these Pigments. Results The mechanism of energy transfer, from the short- to long-wavelength-absorbing Pigments, is largely determined by the relative distances and orientations of the chromophores. In this paper we provide evidence that energy transfer between the B800 and B850 bacteriochlorophylls is largely via Forster induced dipole–dipole resonance. Strong Coulombic (exciton) coupling among the 18 short distanced chromophores in the B850 macrocycle is promoted by good alignment of the Qy dipoles. Singlet–singlet energy transfer from carotenoid to the B800 macrocycle appears to be minimal, with most of the energy transfer going to B850. The higher energy state of both chromophores dominates in more complex situations. Conclusion The structure of the Antenna complex not only shows Nature at its most aesthetic but also illustrates how clever and efficient the energy transfer mechanism has become, with singlet–singlet excitation being passed smoothly down the spectral gradient to the reaction centre.
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Antenna Pigment-Protein Complexes of Higher Plants and Purple Bacteria
Molecular Processes of Photosynthesis, 1994Co-Authors: J. Philip Thornber, Richard J. Cogdell, Parag R. Chitnis, Daryl T. Morishige, Gary F. Peter, Stephen M. Gómez, Shivanthi Anandan, Susanne Preiss, Beth W. Dreyfuss, Angela LeeAbstract:Publisher Summary This chapter focuses on the cellular biochemistry of the light-harvesting components of the higher plant photosystems and of the photosystem in purple bacteria. Common features are readily apparent among the reaction center (RC) complexes of the various groups of photosynthetic organisms. They are far less apparent between their Antenna complexes. This is perhaps to be expected because the organisms carry out the same energy conversion process but are required to be diverse in their light-capturing abilities so that they can occupy a specific niche in the biosphere. Thus, the smallest unit of photosynthetic RCs is composed of two homologous but not identical proteins in all organisms: the L and M subunits of purple bacteria, the D 1 and D2 proteins of photosystem II in green plants, and the two slightly different 68 kDa subunits of CC I in photosystem I. High-resolution crystallography has revealed that the site of the primary photochemical event in the purple bacterial RC is between the L-and M-subunits. The P680 driven reaction in photosystem II will probably be similarly located as will the primary event driven by P700 in photosystem I.
Juraj Dian - One of the best experts on this subject based on the ideXlab platform.
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Spectral hole burning study of photosynthetic Antenna Pigment-protein complexes
Journal of Molecular Structure, 1993Co-Authors: Martin Vacha, F. Adamec, M. Ambrož, Juraj Dian, Jakub Pšenčík, Jan HálaAbstract:Abstract Results of persistent spectral hole burning in fluorescence spectra of photosystem II core Antenna complexes CP 43 and CP 47 are presented. The holewidths (extrapolated to zero burning fluence) yield the excited state population decay times T 1 which are influenced by fast energy transfer within the Antenna complexes. The obtained T 1 values range between 6.6 and 10 ps. The holewidths are independent on temperature within the studied temperature interval 1.5-4.2 K. The observed phenomenon of laser-induced hole filling in the spectra of CP 43 is explained in terms of energy transfer within the CP 43 Pigment-protein complex.
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spectral properties of Antenna Pigment protein complexes studied by hole burning spectroscopy
Journal of Luminescence, 1992Co-Authors: Martin Vacha, F. Adamec, M. Ambrož, Juraj Dian, Jan HálaAbstract:Abstract Persistent spectral hole-burning fluorescence spectra of photosystem II core Antenna at 4.2 were measured. The obtained hole widths were interpreted in terms of fast excited energy transfer within Pigment-protein complexes. The energy transfer efficiency, the inhomogeneous distribution function and hole-burning mechanism are discussed with respect to the role of the surrounding protein environment (polymer, glass). The observed light induced hole filling is also interpreted as a result of efficient energy transfer.
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Spectral properties of Antenna Pigment—protein complexes studied by hole-burning spectroscopy
Journal of Luminescence, 1992Co-Authors: Martin Vacha, F. Adamec, M. Ambrož, Juraj Dian, Jan HálaAbstract:Abstract Persistent spectral hole-burning fluorescence spectra of photosystem II core Antenna at 4.2 were measured. The obtained hole widths were interpreted in terms of fast excited energy transfer within Pigment-protein complexes. The energy transfer efficiency, the inhomogeneous distribution function and hole-burning mechanism are discussed with respect to the role of the surrounding protein environment (polymer, glass). The observed light induced hole filling is also interpreted as a result of efficient energy transfer.