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Santabarbara S, Agostini A, Petrova AA, Bortolus M, Casazza AP, Carbonera D. Chlorophyll triplet states in thylakoid membranes of Acaryochloris marina. Evidence for a triplet state sitting on the photosystem I primary donor populated by intersystem crossing. PHOTOSYNTHESIS RESEARCH 2024; 159:133-152. [PMID: 37191762 DOI: 10.1007/s11120-023-01023-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 04/27/2023] [Indexed: 05/17/2023]
Abstract
Photo-induced triplet states in the thylakoid membranes isolated from the cyanobacterium Acaryocholoris marina, that harbours Chlorophyll (Chl) d as its main chromophore, have been investigated by Optically Detected Magnetic Resonance (ODMR) and time-resolved Electron Paramagnetic Resonance (TR-EPR). Thylakoids were subjected to treatments aimed at poising the redox state of the terminal electron transfer acceptors and donors of Photosystem II (PSII) and Photosystem I (PSI), respectively. Under ambient redox conditions, four Chl d triplet populations were detectable, identifiable by their characteristic zero field splitting parameters, after deconvolution of the Fluorescence Detected Magnetic Resonance (FDMR) spectra. Illumination in the presence of the redox mediator N,N,N',N'-Tetramethyl-p-phenylenediamine (TMPD) and sodium ascorbate at room temperature led to a redistribution of the triplet populations, with T3 (|D|= 0.0245 cm-1, |E|= 0.0042 cm-1) becoming dominant and increasing in intensity with respect to untreated samples. A second triplet population (T4, |D|= 0.0248 cm-1, |E|= 0.0040 cm-1) having an intensity ratio of about 1:4 with respect to T3 was also detectable after illumination in the presence of TMPD and ascorbate. The microwave-induced Triplet-minus-Singlet spectrum acquired at the maximum of the |D|-|E| transition (610 MHz) displays a broad minimum at 740 nm, accompanied by a set of complex spectral features that overall resemble, despite showing further fine spectral structure, the previously reported Triplet-minus-Singlet spectrum attributed to the recombination triplet of PSI reaction centre,3 P 740 [Schenderlein M, Çetin M, Barber J, et al. Spectroscopic studies of the chlorophyll d containing photosystem I from the cyanobacterium Acaryochloris marina. Biochim Biophys Acta 1777:1400-1408]. However, TR-EPR experiments indicate that this triplet displays an eaeaea electron spin polarisation pattern which is characteristic of triplet sublevels populated by intersystem crossing rather than recombination, for which an aeeaae polarisation pattern is expected instead. It is proposed that the observed triplet, which leads to the bleaching of the P740 singlet state, sits on the PSI reaction centre.
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Affiliation(s)
- Stefano Santabarbara
- Photosynthesis Research Unit, Centro Studi Sulla Biologia Cellulare e Molecolare delle Piante, Consiglio Nazionale Delle Ricerche, Via Celoria 26, 20133, Milan, Italy.
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle Ricerche, Via Bassini 15a, 20133, Milan, Italy.
| | - Alessandro Agostini
- Department of Chemical Sciences, Università di Padova, Via Marzolo 1, 35131, Padua, Italy
| | - Anastasia A Petrova
- Photosynthesis Research Unit, Centro Studi Sulla Biologia Cellulare e Molecolare delle Piante, Consiglio Nazionale Delle Ricerche, Via Celoria 26, 20133, Milan, Italy
- A. N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory 1 Building 40, Moscow, Russia, 119992
| | - Marco Bortolus
- Department of Chemical Sciences, Università di Padova, Via Marzolo 1, 35131, Padua, Italy
| | - Anna Paola Casazza
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle Ricerche, Via Bassini 15a, 20133, Milan, Italy
| | - Donatella Carbonera
- Department of Chemical Sciences, Università di Padova, Via Marzolo 1, 35131, Padua, Italy.
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Cherepanov DA, Neverov KV, Obukhov YN, Maleeva YV, Gostev FE, Shelaev IV, Aybush AV, Kritsky MS, Nadtochenko VA. Femtosecond Dynamics of Excited States of Chlorophyll Tetramer in Water-Soluble Chlorophyll-Binding Protein BoWSCP. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1580-1595. [PMID: 38105026 DOI: 10.1134/s0006297923100139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 09/22/2023] [Accepted: 09/22/2023] [Indexed: 12/19/2023]
Abstract
The paper reports on the absorption dynamics of chlorophyll a in a symmetric tetrameric complex of the water-soluble chlorophyll-binding protein BoWSCP. It was measured by a broadband femtosecond laser pump-probe spectroscopy within the range from 400 to 750 nm and with a time resolution of 20 fs-200 ps. When BoWSCP was excited in the region of the Soret band at a wavelength of 430 nm, nonradiative intramolecular conversion S3→S1 was observed with a characteristic time of 83 ± 9 fs. When the complex was excited in the region of the Qy band at 670 nm, relaxation transition between two excitonic states of the chlorophyll dimer was observed in the range of 105 ± 10 fs. Absorption spectra of the excited singlet states S1 and S3 of chlorophyll a were obtained. The delocalization of the excited state between exciton-coupled Chl molecules in BoWSCP tetramer changed in time and depended on the excitation energy. When BoWSCP is excited in the Soret band region, an ultrafast photochemical reaction is observed. This could result from the reduction of tryptophan in the vicinity of chlorophyll.
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Affiliation(s)
- Dmitry A Cherepanov
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia.
- Belozersky Research Institute of Physical and Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Konstantin V Neverov
- Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Moscow, 119071, Russia
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Yuriy N Obukhov
- Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Moscow, 119071, Russia
| | - Yulia V Maleeva
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Feodor E Gostev
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Ivan V Shelaev
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia
- Belozersky Research Institute of Physical and Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Arseny V Aybush
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Michail S Kritsky
- Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Moscow, 119071, Russia
| | - Victor A Nadtochenko
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia.
- Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
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Akhtar P, Lambrev PH. On the spectral properties and excitation dynamics of long-wavelength chlorophylls in higher-plant photosystem I. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2020; 1861:148274. [PMID: 32712151 DOI: 10.1016/j.bbabio.2020.148274] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/13/2020] [Accepted: 07/19/2020] [Indexed: 11/20/2022]
Abstract
In higher-plant Photosystem I (PSI), the majority of "red" chlorophylls (absorbing at longer wavelengths than the reaction centre P700) are located in the peripheral antenna, but contradicting reports are given about red forms in the core complex. Here we attempt to clarify the spectroscopic characteristics and quantify the red forms in the PSI core complex, which have profound implication on understanding the energy transfer and charge separation dynamics. To this end we compare the steady-state absorption and fluorescence spectra and picosecond time-resolved fluorescence kinetics of isolated PSI core complex and PSI-LHCI supercomplex from Pisum sativum recorded at 77 K. Gaussian decomposition of the absorption spectra revealed a broad band at 705 nm in the core complex with an oscillator strength of three chlorophylls. Additional absorption at 703 nm and 711 nm in PSI-LHCI indicated up to five red chlorophylls in the peripheral antenna. Analysis of fluorescence emission spectra resolved states emitting at 705, 715 and 722 nm in the core and additional states around 705-710 nm and 733 nm in PSI-LHCI. The red states compete with P700 in trapping excitations in the bulk antenna, which occurs on a timescale of ~20 ps. The three red forms in the core have distinct decay kinetics, probably in part determined by the rate of quenching by the oxidized P700. These results affirm that the red chlorophylls in the core complex must not be neglected when interpreting kinetic experimental results of PSI.
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Affiliation(s)
- Parveen Akhtar
- Biological Research Centre, Szeged, Temesvári krt. 62, Szeged 6726, Hungary
| | - Petar H Lambrev
- Biological Research Centre, Szeged, Temesvári krt. 62, Szeged 6726, Hungary.
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Cherepanov DA, Brady NG, Shelaev IV, Nguyen J, Gostev FE, Mamedov MD, Nadtochenko VA, Bruce BD. PSI-SMALP, a Detergent-free Cyanobacterial Photosystem I, Reveals Faster Femtosecond Photochemistry. Biophys J 2020; 118:337-351. [PMID: 31882247 PMCID: PMC6976803 DOI: 10.1016/j.bpj.2019.11.3391] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 11/17/2019] [Accepted: 11/26/2019] [Indexed: 12/12/2022] Open
Abstract
Cyanobacterial photosystem I (PSI) functions as a light-driven cyt c6-ferredoxin/oxidoreductase located in the thylakoid membrane. In this work, the energy and charge transfer processes in PSI complexes isolated from Thermosynechococcus elongatus via conventional n-dodecyl-β-D-maltoside solubilization (DM-PSI) and a, to our knowledge, new detergent-free method using styrene-maleic acid copolymers (SMA-PSI) have been investigated by pump-to-probe femtosecond laser spectroscopy. In DM-PSI preparations excited at 740 nm, the excitation remained localized on the long-wavelength chlorophyll forms within 0.1-20 ps and revealed little or no charge separation and oxidation of the special pair, P700. The formation of ion-radical pair P700+A1- occurred with a characteristic time of 36 ps, being kinetically controlled by energy transfer from the long-wavelength chlorophyll to P700. Quite surprisingly, the detergent-free SMA-PSI complexes upon excitation by these long-wave pulses undergo an ultrafast (<100 fs) charge separation in ∼45% of particles. In the remaining complexes (∼55%), the energy transfer to P700 occurred at ∼36 ps, similar to the DM-PSI. Both isolation methods result in a trimeric form of PSI, yet the SMA-PSI complexes display a heterogenous kinetic behavior. The much faster rate of charge separation suggests the existence of an ultrafast pathway for charge separation in the SMA-PSI that may be disrupted during detergent isolation.
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Affiliation(s)
- Dmitry A Cherepanov
- N. N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Nathan G Brady
- Biochemistry and Cellular and Molecular Biology Department, University of Tennessee, Knoxville, Tennessee
| | - Ivan V Shelaev
- N. N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Jon Nguyen
- Biochemistry and Cellular and Molecular Biology Department, University of Tennessee, Knoxville, Tennessee
| | - Fedor E Gostev
- N. N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Mahir D Mamedov
- A. N. Belozersky Institute of Physical-Chemical Biology, Moscow State University, Moscow, Russia
| | - Victor A Nadtochenko
- N. N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia.
| | - Barry D Bruce
- Biochemistry and Cellular and Molecular Biology Department, University of Tennessee, Knoxville, Tennessee; Energy Science & Engineering Program, The Bredesen Center, University of Tennessee, Knoxville, Tennessee.
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Mechanism of adiabatic primary electron transfer in photosystem I: Femtosecond spectroscopy upon excitation of reaction center in the far-red edge of the QY band. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:895-905. [DOI: 10.1016/j.bbabio.2017.08.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 08/14/2017] [Accepted: 08/16/2017] [Indexed: 11/23/2022]
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Mokvist F, Mamedov F, Styring S. Defining the far-red limit of photosystem I: the primary charge separation is functional to 840 nm. J Biol Chem 2014; 289:24630-9. [PMID: 25023284 DOI: 10.1074/jbc.m114.555649] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The far-red limit of photosystem I (PS I) photochemistry was studied by EPR spectroscopy using laser flashes between 730 and 850 nm. In manganese-depleted spinach thylakoid membranes, the primary donor in PS I, P700, was oxidized simultaneously with tyrosine Z, the secondary donor in PS II. It was found that at 295 K PS I photochemistry, observed as P700 (+) formation, was functional up to 840 nm. This is 30 nm further to the red region than was reported for PS II photochemistry (Thapper, A., Mamedov, F., Mokvist, F., Hammarström, L., and Styring, S. (2009) Plant Cell 21, 2391-2401). The same far-red limit for the P700 (+) formation was observed in a PS I reaction center core preparation from Nostoc punctiforme. The reduction of the acceptor side of PS I, observed as reduction of the iron-sulfur centers FA and FB by low temperature EPR measurements, was also functional at 15 K with light up to >830 nm. Taken together, these results, obtained from both plants and cyanobacteria, most likely rule out involvement of the red-absorbing antenna chlorophylls in this reaction. Instead we propose the existence of weak charge transfer bands absorbing in the far-red region in the ensemble of excitonically coupled chlorophyll a molecules around P700 similar to what has been found in the reaction center of PS II. These charge transfer bands could be responsible for the far-red light absorption leading to PS I photochemistry at wavelengths up to 840 nm.
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Affiliation(s)
- Fredrik Mokvist
- From Molecular Biomimetics, Department of Chemistry-Ångström, Uppsala University, Ångström Laboratory, P. O. Box 523, S-751 20 Uppsala, Sweden
| | - Fikret Mamedov
- From Molecular Biomimetics, Department of Chemistry-Ångström, Uppsala University, Ångström Laboratory, P. O. Box 523, S-751 20 Uppsala, Sweden
| | - Stenbjörn Styring
- From Molecular Biomimetics, Department of Chemistry-Ångström, Uppsala University, Ångström Laboratory, P. O. Box 523, S-751 20 Uppsala, Sweden
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Madjet MEA, Müh F, Renger T. Deciphering the influence of short-range electronic couplings on optical properties of molecular dimers: application to "special pairs" in photosynthesis. J Phys Chem B 2009; 113:12603-14. [PMID: 19697949 DOI: 10.1021/jp906009j] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The excited states of chromophore dimers are, in general, delocalized, and the transition energies and transition dipoles are different from those of the monomers. The intermolecular interaction that is responsible for these effects has two contributions: Forster-type Coulomb coupling and a short-range coupling, which depends on the intermolecular overlap of electronic wave functions. The latter contains the Dexter-type exchange coupling and the coupling of excited states to intermolecular charge-transfer (CT) states. Recently, we developed a method (TrEsp) for an accurate and numerically efficient calculation of the Forster-type Coulomb part (Madjet et al. J. Phys. Chem. B 2006, 110, 17268). Here, we combine the latter with quantum chemical calculations to evaluate the short-range contribution, extending a method developed earlier by Scholes et al. (J. Phys. Chem. B 1999, 103, 2543). An effective two-state model is used, which relates the transition energies and transition dipole moments obtained by quantum chemical calculations of the monomers to those calculated for the dimer. From this relation, the short-range excitonic coupling and effective shifts of the local transition energies due to the coupling to intermolecular CT states can be inferred including a consistency check to evaluate quantum chemical methods that differ in the treatment of electron correlation. The method is applied to the special pairs of the reaction centers of purple bacteria (bRC) and photosystem I (PSI). We find that the short-range coupling represents the dominant contribution to the total excitonic coupling in both special pairs (80% in PSI and 70% in the bRC) and exhibits a monoexponential dependence on the distance between the pi-planes of the pigments with an attenuation factor of 2.8 A(-1). We obtain significant red-shifts of the local transition energies, which show a biexponential distance dependence with one attenuation factor being 2.8 A(-1) and another factor being in the range 0.3-0.7 A(-1) for PSI and 0.8-0.9 A(-1) for bRC. Both effects of the short-range coupling determine the excitation energy sink in the reaction centers at the special pairs.
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Affiliation(s)
- Mohamed El-Amine Madjet
- Freie Universitat Berlin, Institut fur Chemie und Biochemie, Fabeckstrasse 36a, D-14195 Berlin, Germany
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Purchase R, Völker S. Spectral hole burning: examples from photosynthesis. PHOTOSYNTHESIS RESEARCH 2009; 101:245-66. [PMID: 19714478 PMCID: PMC2744831 DOI: 10.1007/s11120-009-9484-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 07/31/2009] [Indexed: 05/14/2023]
Abstract
The optical spectra of photosynthetic pigment-protein complexes usually show broad absorption bands, often consisting of a number of overlapping, "hidden" bands belonging to different species. Spectral hole burning is an ideal technique to unravel the optical and dynamic properties of such hidden species. Here, the principles of spectral hole burning (HB) and the experimental set-up used in its continuous wave (CW) and time-resolved versions are described. Examples from photosynthesis studied with hole burning, obtained in our laboratory, are then presented. These examples have been classified into three groups according to the parameters that were measured: (1) hole widths as a function of temperature, (2) hole widths as a function of delay time and (3) hole depths as a function of wavelength. Two examples from light-harvesting (LH) 2 complexes of purple bacteria are given within the first group: (a) the determination of energy-transfer times from the chromophores in the B800 ring to the B850 ring, and (b) optical dephasing in the B850 absorption band. One example from photosystem II (PSII) sub-core complexes of higher plants is given within the second group: it shows that the size of the complex determines the amount of spectral diffusion measured. Within the third group, two examples from (green) plants and purple bacteria have been chosen for: (a) the identification of "traps" for energy transfer in PSII sub-core complexes of green plants, and (b) the uncovering of the lowest k = 0 exciton-state distribution within the B850 band of LH2 complexes of purple bacteria. The results prove the potential of spectral hole burning measurements for getting quantitative insight into dynamic processes in photosynthetic systems at low temperature, in particular, when individual bands are hidden within broad absorption bands. Because of its high-resolution wavelength selectivity, HB is a technique that is complementary to ultrafast pump-probe methods. In this review, we have provided an extensive bibliography for the benefit of scientists who plan to make use of this valuable technique in their future research.
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Affiliation(s)
- Robin Purchase
- Huygens and Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Silvia Völker
- Huygens and Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
- Department of Biophysics, Faculty of Exact Sciences, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
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Schlodder E, Shubin VV, El-Mohsnawy E, Roegner M, Karapetyan NV. Steady-state and transient polarized absorption spectroscopy of photosytem I complexes from the cyanobacteria Arthrospira platensis and Thermosynechococcus elongatus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:732-41. [PMID: 17321489 DOI: 10.1016/j.bbabio.2007.01.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Revised: 01/05/2007] [Accepted: 01/22/2007] [Indexed: 11/29/2022]
Abstract
Core antenna and reaction centre of photosystem I (PS I) complexes from the cyanobacteria Arthrospira platensis and Thermosynechococcus elongatus have been characterized by steady-state polarized absorption spectroscopy, including linear dichroism (LD) and circular dichroism (CD). CD spectra and the second derivatives of measured 77 K CD spectra reveal the spectral components found in the polarized absorption spectra indicating the excitonic origin of the spectral forms of chlorophyll in the PS I complexes. The CD bands at 669-670(+), 673(+), 680(-), 683-685(-), 696-697(-), and 711(-) nm are a common feature of used PSI complexes. The 77 K CD spectra of the trimeric PS I complexes exhibit also low amplitude components around 736 nm for A. platensis and 720 nm for T. elongatus attributed to red-most chlorophylls. The LD measurements indicate that the transition dipole moments of the red-most states are oriented parallel to the membrane plane. The formation of P700(+)A(1)(-) or (3)P700 was monitored by time-resolved difference absorbance and LD spectroscopy to elucidate the spectral properties of the PS I reaction centre. The difference spectra give strong evidence for the delocalization of the excited singlet states in the reaction centre. Therefore, P700 cannot be considered as a dimer but should be regarded as a multimer of the six nearly equally coupled reaction centre chlorophylls in accordance with structure-based calculations. On the basis of the results presented in this work and earlier work in the literature it is concluded that the triplet state is localized most likely on P(A), whereas the cation is localized most likely on P(B).
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Affiliation(s)
- Eberhard Schlodder
- Max-Volmer-Laboratorium für Biophysikalische Chemie, Technische Universität Berlin, Strasse des 17.Juni 135, 10623 Berlin, Germany.
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Gibasiewicz K, Szrajner A, Ihalainen JA, Germano M, Dekker JP, van Grondelle R. Characterization of Low-Energy Chlorophylls in the PSI-LHCI Supercomplex from Chlamydomonas reinhardtii. A Site-Selective Fluorescence Study. J Phys Chem B 2005; 109:21180-6. [PMID: 16853744 DOI: 10.1021/jp0530909] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Almost all photosystem I (PSI) complexes from oxygenic photosynthetic organisms contain chlorophylls that absorb at longer wavelength than that of the primary electron donor P700. We demonstrate here that the low-energy pool of chlorophylls in the PSI-LHCI complex from the green alga Chlamydomonas reinhardtii, containing five to six pigments, is significantly blue-shifted (A(max) at 700 nm at 4 K) compared to that in the PSI core preparations from several species of cyanobacteria and in PSI-LHCI particles from higher plants. This makes them almost isoenergetic with the primary donor. However, they keep the other characteristic features of "red" chlorophylls: clear spectral separation from the bulk chlorophylls, big Stokes shift revealing pronounced electron-phonon coupling, and large homogeneous and inhomogeneous broadening of approximately 170 and approximately 310 cm(-1), respectively.
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Affiliation(s)
- Krzysztof Gibasiewicz
- Department of Physics and Astronomy, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
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Witt H, Bordignon E, Carbonera D, Dekker JP, Karapetyan N, Teutloff C, Webber A, Lubitz W, Schlodder E. Species-specific differences of the spectroscopic properties of P700: analysis of the influence of non-conserved amino acid residues by site-directed mutagenesis of photosystem I from Chlamydomonas reinhardtii. J Biol Chem 2003; 278:46760-71. [PMID: 12933812 DOI: 10.1074/jbc.m304776200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We applied optical spectroscopy, magnetic resonance techniques, and redox titrations to investigate the properties of the primary electron donor P700 in photosystem I (PS I) core complexes from cyanobacteria (Thermosynechococcus elongatus, Spirulina platensis, and Synechocystis sp. PCC 6803), algae (Chlamydomonas reinhardtii CC2696), and higher plants (Spinacia oleracea). Remarkable species-specific differences of the optical properties of P700 were revealed monitoring the (3P700-P700) and (P700+.-P700) absorbance and CD difference spectra. The main bleaching band in the Qy region differs in peak position and line width for the various species. In cyanobacteria the absorbance of P700 extends more to the red compared with algae and higher plants which is favorable for energy transfer from red core antenna chlorophylls to P700 in cyanobacteria. The amino acids in the environment of P700 are highly conserved with two distinct deviations. In C. reinhardtii a Tyr is found at position PsaB659 instead of a Trp present in all other organisms, whereas in Synechocystis a Phe is found instead of a Trp at the homologous position PsaA679. We constructed several mutants in C. reinhardtii CC2696. Strikingly, no PS I could be detected in the mutant YW B659 indicating steric constraints unique to this organism. In the mutants WA A679 and YA B659 significant changes of the spectral features in the (3P700-P700), the (P700+.-P700) absorbance difference and in the (P700+.-P700) CD difference spectra are induced. The results indicate structural differences among PS I from higher plants, algae, and cyanobacteria and give further insight into specific protein-cofactor interactions contributing to the optical spectra.
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Affiliation(s)
- Heike Witt
- Max-Volmer-Laboratorium für Biophysikalische Chemie, Technische Universität Berlin, Strasse des 17, Juni 135, 10623 Berlin, Germany,
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Yang M, Fleming GR. Construction of kinetic domains in energy trapping processes and application to a photosynthetic light harvesting complex. J Chem Phys 2003. [DOI: 10.1063/1.1599347] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Yang M, Damjanović A, Vaswani HM, Fleming GR. Energy transfer in photosystem I of cyanobacteria Synechococcus elongatus: model study with structure-based semi-empirical Hamiltonian and experimental spectral density. Biophys J 2003; 85:140-58. [PMID: 12829471 PMCID: PMC1303072 DOI: 10.1016/s0006-3495(03)74461-0] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2002] [Accepted: 03/07/2003] [Indexed: 10/21/2022] Open
Abstract
We model the energy transfer and trapping kinetics in PSI. Rather than simply applying Förster theory, we develop a new approach to self-consistently describe energy transfer in a complex with heterogeneous couplings. Experimentally determined spectral densities are employed to calculate the energy transfer rates. The absorption spectrum and fluorescence decay time components of the complex at room temperature were reasonably reproduced. The roles of the special chlorophylls (red, linker, and reaction center, respectively) molecules are discussed. A formally exact expression for the trapping time is derived in terms of the intrinsic trapping time, mean first passage time to trap, and detrapping time. The energy transfer mechanism is discussed and the slowest steps of the arrival at the primary electron donor are found to contain two dominant steps: transfer-to-reaction-center, and transfer-to-trap-from-reaction-center. The intrinsic charge transfer time is estimated to be 0.8 approximately 1.7 ps. The optimality with respect to the trapping time of the calculated transition energies and the orientation of Chls is discussed.
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Affiliation(s)
- Mino Yang
- Department of Chemistry, University of California, Berkeley, California, USA
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Frese RN, Palacios MA, Azzizi A, van Stokkum IHM, Kruip J, Rögner M, Karapetyan NV, Schlodder E, van Grondelle R, Dekker JP. Electric field effects on red chlorophylls, beta-carotenes and P700 in cyanobacterial Photosystem I complexes. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1554:180-91. [PMID: 12160991 DOI: 10.1016/s0005-2728(02)00242-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We have probed the absorption changes due to an externally applied electric field (Stark effect) of Photosystem I (PSI) core complexes from the cyanobacteria Synechocystis sp. PCC 6803, Synechococcus elongatus and Spirulina platensis. The results reveal that the so-called C719 chlorophylls in S. elongatus and S. platensis are characterized by very large polarizability differences between the ground and electronically excited states (with Tr(Deltaalpha) values up to about 1000 A(3) f(-2)) and by moderately high change in permanent dipole moments (with average Deltamu values between 2 and 3 D f(-1)). The C740 chlorophylls in S. platensis and, in particular, the C708 chlorophylls in all three species give rise to smaller Stark shifts, which are, however, still significantly larger than those found before for monomeric chlorophyll. The results confirm the hypothesis that these states originate from strongly coupled chlorophyll a molecules. The absorption and Stark spectra of the beta-carotene molecules are almost identical in all complexes and suggest similar or slightly higher values for Tr(Deltaalpha) and Deltamu than for those of beta-carotene in solution. Oxidation of P700 did not significantly change the Stark response of the carotenes and the red antenna states C719 and C740, but revealed in all PSI complexes changes around 700-705 and 690-693 nm, which we attribute to the change in permanent dipole moments of reduced P700 and the chlorophylls responsible for the strong absorption band at 690 nm with oxidized P700, respectively.
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Affiliation(s)
- Raoul N Frese
- Division of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1081, 1081HV, Amsterdam, The Netherlands.
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16
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Zazubovich V, Matsuzaki S, Johnson T, Hayes J, Chitnis P, Small G. Red antenna states of photosystem I from cyanobacterium Synechococcus elongatus: a spectral hole burning study. Chem Phys 2002. [DOI: 10.1016/s0301-0104(01)00535-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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17
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Reinot T, Zazubovich V, Hayes JM, Small GJ. New Insights on Persistent Nonphotochemical Hole Burning and Its Application to Photosynthetic Complexes. J Phys Chem B 2001. [DOI: 10.1021/jp010126y] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tonu Reinot
- Department of Chemistry and Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011
| | - Valter Zazubovich
- Department of Chemistry and Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011
| | - John M. Hayes
- Department of Chemistry and Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011
| | - Gerald J. Small
- Department of Chemistry and Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011
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18
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Jelezko F, Tietz C, Gerken U, Wrachtrup J, Bittl R. Single-Molecule Spectroscopy on Photosystem I Pigment−Protein Complexes. J Phys Chem B 2000. [DOI: 10.1021/jp001332t] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- F. Jelezko
- 3. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany, and Technische Universität Berlin, Max-Volmer-Institut für Biophysikalische Chemie und Biochemie, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - C. Tietz
- 3. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany, and Technische Universität Berlin, Max-Volmer-Institut für Biophysikalische Chemie und Biochemie, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - U. Gerken
- 3. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany, and Technische Universität Berlin, Max-Volmer-Institut für Biophysikalische Chemie und Biochemie, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - J. Wrachtrup
- 3. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany, and Technische Universität Berlin, Max-Volmer-Institut für Biophysikalische Chemie und Biochemie, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - R. Bittl
- 3. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany, and Technische Universität Berlin, Max-Volmer-Institut für Biophysikalische Chemie und Biochemie, Strasse des 17. Juni 135, 10623 Berlin, Germany
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Hayes JM, Matsuzaki S, Rätsep M, Small GJ. Red Chlorophyll a Antenna States of Photosystem I of the Cyanobacterium Synechocystis sp. PCC 6803. J Phys Chem B 2000. [DOI: 10.1021/jp000447u] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- J. M. Hayes
- Ames LaboratoryU.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011
| | - S. Matsuzaki
- Ames LaboratoryU.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011
| | - M. Rätsep
- Ames LaboratoryU.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011
| | - G. J. Small
- Ames LaboratoryU.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011
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20
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Melkozernov AN, Lin S, Blankenship RE. Femtosecond transient spectroscopy and excitonic interactions in Photosystem I. J Phys Chem B 2000; 104:1651-6. [PMID: 11543525 DOI: 10.1021/jp993257w] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ultrafast dynamics of excitation transfer in the Photosystem I (PSI) core antenna from the cyanobacterium Synechocystis sp. PCC 6803 were detected at 77 K by using femtosecond transient absorption spectroscopy with selective excitation at 700, 695, and 710 nm. At low temperature, the efficiency of uphill energy transfer in the core antenna significantly decreases. As a result, the spectral profile of the PSI equilibrated antenna shifts to lower energies because of a change of chlorophyll (Chl) excited-state distribution. Observed on a 2-ns time scale, P700 photooxidation spectra are largely excitation wavelength independent. In the early time spectra, excitation of P700 induces transient photobleaching at 698 nm accompanied by a resonant photobleaching band at 683 nm decaying within 250-300 fs. Chemical oxidation of P700 does not affect the transient band at 683 nm. This band is also present in 200-fs spectra induced by selective excitation of Chls at 710 nm (red pigments C708), which suggests that this high-energy transition may reflect an excitonic interaction between pigments of the reaction center and closely located red pigments. Possible candidates for the interacting molecules in the 4-angstroms crystal structure of cyanobacterial PSI are discussed.
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Affiliation(s)
- A N Melkozernov
- Department of Chemistry and Biochemistry, Center for the Study of Early Events in Photosynthesis, Arizona State University, Tempe 85287-1604, USA
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21
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Rätsep M, Johnson TW, Chitnis PR, Small GJ. The Red-Absorbing Chlorophyll a Antenna States of Photosystem I: A Hole-Burning Study of Synechocystis sp. PCC 6803 and Its Mutants. J Phys Chem B 2000. [DOI: 10.1021/jp9929418] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Rätsep
- Ames Laboratory−U.S. Department of Energy and Departments of Chemistry, and Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011
| | - T. W. Johnson
- Ames Laboratory−U.S. Department of Energy and Departments of Chemistry, and Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011
| | - P. R. Chitnis
- Ames Laboratory−U.S. Department of Energy and Departments of Chemistry, and Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011
| | - G. J. Small
- Ames Laboratory−U.S. Department of Energy and Departments of Chemistry, and Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011
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Pålsson LO, Flemming C, Gobets B, van Grondelle R, Dekker JP, Schlodder E. Energy transfer and charge separation in photosystem I: P700 oxidation upon selective excitation of the long-wavelength antenna chlorophylls of Synechococcus elongatus. Biophys J 1998; 74:2611-22. [PMID: 9591685 PMCID: PMC1299601 DOI: 10.1016/s0006-3495(98)77967-6] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Photosystem I of the cyanobacterium Synechococcus elongatus contains two spectral pools of chlorophylls called C-708 and C-719 that absorb at longer wavelengths than the primary electron donor P700. We investigated the relative quantum yields of photochemical charge separation and fluorescence as a function of excitation wavelength and temperature in trimeric and monomeric photosystem I complexes of this cyanobacterium. The monomeric complexes are characterized by a reduced content of the C-719 spectral form. At room temperature, an analysis of the wavelength dependence of P700 oxidation indicated that all absorbed light, even of wavelengths of up to 750 nm, has the same probability of resulting in a stable P700 photooxidation. Upon cooling from 295 K to 5 K, the nonselectively excited steady-state emission increased by 11- and 16-fold in the trimeric and monomeric complexes, respectively, whereas the quantum yield of P700 oxidation decreased 2.2- and 1.7-fold. Fluorescence excitation spectra at 5 K indicate that the fluorescence quantum yield further increases upon scanning of the excitation wavelength from 690 nm to 710 nm, whereas the quantum yield of P700 oxidation decreases significantly upon excitation at wavelengths longer than 700 nm. Based on these findings, we conclude that at 5 K the excited state is not equilibrated over the antenna before charge separation occurs, and that approximately 50% of the excitations reach P700 before they become irreversibly trapped on one of the long-wavelength antenna pigments. Possible spatial organizations of the long-wavelength antenna pigments in the three-dimensional structure of photosystem I are discussed.
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Affiliation(s)
- L O Pålsson
- Department of Physics and Astronomy, Institute of Molecular Biological Sciences, Vrije Universiteit, Amsterdam, The Netherlands
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Vrieze J, Gast P, Hoff AJ. Structure of the Reaction Center of Photosystem I of Plants. An Investigation with Linear-Dichroic Absorbance-Detected Magnetic Resonance. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp9524789] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- J. Vrieze
- Department of Biophysics, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - P. Gast
- Department of Biophysics, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - A. J. Hoff
- Department of Biophysics, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
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25
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Pålsson LO, Dekker JP, Schlodder E, Monshouwer R, van Grondelle R. Polarized site-selective fluorescence spectroscopy of the long-wavelength emitting chlorophylls in isolated Photosystem I particles of Synechococcus elongatus. PHOTOSYNTHESIS RESEARCH 1996; 48:239-46. [PMID: 24271304 DOI: 10.1007/bf00041014] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/1995] [Accepted: 02/14/1996] [Indexed: 05/24/2023]
Abstract
Isolated trimeric Photosystem I complexes of the cyanobacterium Synechococcus elongatus have been studied with absorption spectroscopy and site-selective polarized fluorescence spectroscopy at cryogenic temperatures. The 4 K absorption spectrum exhibits a clear and distinct peak at 710 nm and shoulders near 720, 698 and 692 nm apart from the strong absorption profile located at 680 nm. Deconvoluting the 4 K absorption spectrum with Gaussian components revealed that Synechococcus elongatus contains two types of long-wavelength pigments peaking at 708 nm and 719 nm, which we denoted C-708 and C-719, respectively. An estimate of the oscillator strengths revealed that Synechococcus elongatus contains about 4-5 C-708 pigments and 5-6 C-719 pigments. At 4 K and for excitation wavelengths shorter than 712 nm, the emission maximum appeared at 731 nm. For excitation wavelengths longer than 712 nm, the emission maximum shifted to the red, and for excitation in the far red edge of the absorption spectrum the emission maximum was observed 10-11 nm to the red with respect to the excitation wavelength, which indicates that the Stokes shift of C-719 is 10-11 nm. The fluorescence anisotropy, as calculated in the emission maximum, reached a maximal anisotropy of r=0.35 for excitation in the far red edge of the absorption spectrum (at and above 730 nm), and showed a complicated behavior for excitation at shorter wavelengths. The results suggest efficient energy transfer routes between C-708 and C-719 pigments and also among the C-719 pigments.
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Affiliation(s)
- L O Pålsson
- Department of Physics and Astronomy, Vrije Universiteit, De Boelelean 1081, 1081 HV, Amsterdam, The Netherlands
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26
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On the validity of the standard model for primary charge separation in the bacterial reaction center. Chem Phys 1995. [DOI: 10.1016/0301-0104(95)00089-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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27
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Gobets B, van Amerongen H, Monshouwer R, Kruip J, Rögner M, van Grondelle R, Dekker JP. Polarized site-selected fluorescence spectroscopy of isolated Photosystem I particles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1994. [DOI: 10.1016/0005-2728(94)90024-8] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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28
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Reddy NR, Kolaczkowski SV, Small GJ. A Photoinduced Persistent Structural Transformation of the Special Pair of a Bacterial Reaction Center. Science 1993; 260:68-71. [PMID: 17793534 DOI: 10.1126/science.260.5104.68] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Structural modification of photosynthetic reaction centers is an important approach for understanding their charge-separation processes. An unprecedented persistent structural transformation of the special pair (dimer) of bacteriochlorophyll molecules can be produced by light absorption alone. The nonphotochemical hole-burned spectra for the reaction center of Rhodopseudomonas viridis show that the phototransformation leads to a red shift of 150 wave numbers for the special pair's lowest energy absorption band, P960, and a comparable blue shift for a state at 850 nanometers, which can now be definitively assigned as being most closely associated with the upper dimer component. Additional insights on excited-state electronic structure include the identification of a new state.
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30
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Reddy NR, Lyle PA, Small GJ. Applications of spectral hole burning spectroscopies to antenna and reaction center complexes. PHOTOSYNTHESIS RESEARCH 1992; 31:167-194. [PMID: 24408059 DOI: 10.1007/bf00035536] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/1991] [Accepted: 09/27/1991] [Indexed: 06/03/2023]
Abstract
The underlying principles of spectral hole burning spectroscopies and the theory for hole profiles are reviewed and illustrated with calculated spectra. The methodology by which the dependence of the overall hole profile on burn wavelength can be used to reveal the contributions from site inhomogeneous broadening and various homogeneous broadening contributions to the broad Qy-absorption bands of cofactors is emphasized. Applications to the primary electron donor states of the reaction centers of purple bacteria and Photosystems I and II of green plants are discussed. The antenna (light harvesting) complexes considered include B800-B850 and B875 of Rhodobacter sphaeroides and the base-plate complex of Prosthecochloris aestuarii with particular attention being given to excitonic interactions and level structure. The data presented show that spectral hole burning is a generally applicable low temperature approach for the study of excited state electronic and vibrational (intramolecular, phonon) structures, structural heterogeneity and excited state lifetimes.
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Affiliation(s)
- N R Reddy
- Ames Laboratory-USDOE, Iowa State University, 50011, Ames, IA, USA
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31
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Spectroscopic properties of LHC-II, the main light-harvesting chlorophyll a/b protein complex from chloroplast membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1992. [DOI: 10.1016/s0005-2728(05)80331-7] [Citation(s) in RCA: 130] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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32
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Abstract
Quadratic Stark effect in CP1 pigment-protein complex was examined at low temperatures in the red spectral region. The Stark spectra of samples containing P700 in reduced form exhibit a strong negative band at 704 nm, which disappears on chemical oxidation of P700. The change in permanent dipole moment, delta mu, of P700 on electronic excitation estimated from these spectra was found to be between 4.7 and 7.7 Debye units. It is suggested to reflect the charge-transfer contribution to the excited state of P700. For antenna chlorophyll, delta mu approximately equal to 1 D was obtained in accordance with the data for monomeric chlorophyll.
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Affiliation(s)
- S Krawczyk
- Institute of Physics, M. Curie-Skłodowska University, Lublin, Poland
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33
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Vacha M, Adamec F, Ambroz M, Baumruk V, Dian J, Nedbal L, Hala J. HOLE-BURNING SPECTROSCOPY OF ACTIVE AND INACTIVATEE) PHOTOSYSTEM II PARTICLES. Photochem Photobiol 1991. [DOI: 10.1111/j.1751-1097.1991.tb01995.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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34
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Energy transfer dynamics of the B800—B850 antenna complex of Rhodobacter sphaeroides: a hole burning study. Chem Phys Lett 1991. [DOI: 10.1016/0009-2614(91)90369-k] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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