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Cherepanov D, Aybush A, Johnson TW, Shelaev I, Gostev F, Mamedov M, Nadtochenko V, Semenov A. Inverted region in the reaction of the quinone reduction in the A 1-site of photosystem I from cyanobacteria. PHOTOSYNTHESIS RESEARCH 2024; 159:115-131. [PMID: 37093503 DOI: 10.1007/s11120-023-01020-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Accepted: 04/13/2023] [Indexed: 05/03/2023]
Abstract
Photosystem I from the menB strain of Synechocystis sp. PCC 6803 containing foreign quinones in the A1 sites was used for studying the primary steps of electron transfer by pump-probe femtosecond laser spectroscopy. The free energy gap (- ΔG) of electron transfer between the reduced primary acceptor A0 and the quinones bound in the A1 site varied from 0.12 eV for the low-potential 1,2-diamino-anthraquinone to 0.88 eV for the high-potential 2,3-dichloro-1,4-naphthoquinone, compared to 0.5 eV for the native phylloquinone. It was shown that the kinetics of charge separation between the special pair chlorophyll P700 and the primary acceptor A0 was not affected by quinone substitutions, whereas the rate of A0 → A1 electron transfer was sensitive to the redox-potential of quinones: the decrease of - ΔG by 400 meV compared to the native phylloquinone resulted in a ~ fivefold slowing of the reaction The presence of the asymmetric inverted region in the ΔG dependence of the reaction rate indicates that the electron transfer in photosystem I is controlled by nuclear tunneling and should be treated in terms of quantum electron-phonon interactions. A three-mode implementation of the multiphonon model, which includes modes around 240 cm-1 (large-scale protein vibrations), 930 cm-1 (out-of-plane bending of macrocycles and protein backbone vibrations), and 1600 cm-1 (double bonds vibrations) was applied to rationalize the observed dependence. The modes with a frequency of at least 1600 cm-1 make the predominant contribution to the reorganization energy, while the contribution of the "classical" low-frequency modes is only 4%.
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Affiliation(s)
- Dmitry Cherepanov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina Street 4, Moscow, Russia, 119991.
- A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory 1, bldg 40, Moscow, Russia, 119992.
| | - Arseny Aybush
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina Street 4, Moscow, Russia, 119991
| | - T Wade Johnson
- Department of Chemistry, Susquehanna University, 514 University Ave., Selinsgrove, PA, 17870, USA
| | - Ivan Shelaev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina Street 4, Moscow, Russia, 119991
| | - Fedor Gostev
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina Street 4, Moscow, Russia, 119991
| | - Mahir Mamedov
- A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory 1, bldg 40, Moscow, Russia, 119992
| | - Victor Nadtochenko
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina Street 4, Moscow, Russia, 119991
- Department of Chemistry, Lomonosov Moscow State University, Leninskiye Gory 1-3, Moscow, Russia, 119991
| | - Alexey Semenov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Kosygina Street 4, Moscow, Russia, 119991.
- A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory 1, bldg 40, Moscow, Russia, 119992.
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Prince RC, Dutton PL, Gunner MR. The aprotic electrochemistry of quinones. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148558. [PMID: 35413248 DOI: 10.1016/j.bbabio.2022.148558] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 03/26/2022] [Accepted: 04/05/2022] [Indexed: 05/09/2023]
Abstract
Quinones play important roles in biological electron transfer reactions in almost all organisms, with specific roles in many physiological processes and chemotherapy. Quinones participate in two-electron, two-proton reactions in aqueous solution at equilibrium near neutral pH, but protons often lag behind the electron transfers. The relevant reactions in proteins are often sequential one electron redox processes without involving protons. Here we report the aprotic electrochemistry of the two half-couples, Q/Q.- and Q.-/Q=, of 11 parent quinones and 118 substituted 1,4-benzoquinones, 91 1,4-naphthoquinones, and 107 9,10-anthraquinones. The measured redox potentials are fit quite well with the Hammett para sigma (σpara) parameter. Occasional exceptions can involve important groups, such as methoxy substituents in ubiquinone and hydroxy substituents in therapeutics. These can generally be explained by reasonable conjectures involving steric clashes and internal hydrogen bonds. We also provide data for 25 other quinones, 2 double quinones and 15 non-quinones, all measured under similar conditions.
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Affiliation(s)
| | - P Leslie Dutton
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 10104, USA
| | - M R Gunner
- Physics Department City College of New York in the City University of New York, NY 10031, USA.
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3
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Tani K, Kanno R, Ji XC, Hall M, Yu LJ, Kimura Y, Madigan MT, Mizoguchi A, Humbel BM, Wang-Otomo ZY. Cryo-EM Structure of the Photosynthetic LH1-RC Complex from Rhodospirillum rubrum. Biochemistry 2021; 60:2483-2491. [PMID: 34323477 DOI: 10.1021/acs.biochem.1c00360] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rhodospirillum (Rsp.) rubrum is one of the most widely used model organisms in bacterial photosynthesis. This purple phototroph is characterized by the presence of both rhodoquinone (RQ) and ubiquinone as electron carriers and bacteriochlorophyll (BChl) a esterified at the propionic acid side chain by geranylgeraniol (BChl aG) instead of phytol. Despite intensive efforts, the structure of the light-harvesting-reaction center (LH1-RC) core complex from Rsp. rubrum remains at low resolutions. Using cryo-EM, here we present a robust new view of the Rsp. rubrum LH1-RC at 2.76 Å resolution. The LH1 complex forms a closed, slightly elliptical ring structure with 16 αβ-polypeptides surrounding the RC. Our biochemical analysis detected RQ molecules in the purified LH1-RC, and the cryo-EM density map specifically positions RQ at the QA site in the RC. The geranylgeraniol side chains of BChl aG coordinated by LH1 β-polypeptides exhibit a highly homologous tail-up conformation that allows for interactions with the bacteriochlorin rings of nearby LH1 α-associated BChls aG. The structure also revealed key protein-protein interactions in both N- and C-terminal regions of the LH1 αβ-polypeptides, mainly within a face-to-face structural subunit. Our high-resolution Rsp. rubrum LH1-RC structure provides new insight for evaluating past experimental and computational results obtained with this old organism over many decades and lays the foundation for more detailed exploration of light-energy conversion, quinone transport, and structure-function relationships in this pigment-protein complex.
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Affiliation(s)
- Kazutoshi Tani
- Graduate School of Medicine, Mie University, Tsu, Mie 514-8507, Japan
| | - Ryo Kanno
- Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1, Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
| | - Xuan-Cheng Ji
- Faculty of Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - Malgorzata Hall
- Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1, Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
| | - Long-Jiang Yu
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Yukihiro Kimura
- Department of Agrobioscience, Graduate School of Agriculture, Kobe University, Nada, Kobe, Hyogo 657-8501, Japan
| | - Michael T Madigan
- School of Biological Sciences, Southern Illinois University, Carbondale, Illinois 62901, United States
| | - Akira Mizoguchi
- Graduate School of Medicine, Mie University, Tsu, Mie 514-8507, Japan
| | - Bruno M Humbel
- Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1, Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
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Gibasiewicz K, Pajzderska M, Białek R, Jones MR. Temperature dependence of nanosecond charge recombination in mutant Rhodobacter sphaeroides reaction centers: modelling of the protein dynamics. Photochem Photobiol Sci 2021; 20:913-922. [PMID: 34213754 DOI: 10.1007/s43630-021-00069-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 06/18/2021] [Indexed: 10/20/2022]
Abstract
We investigated the influence of a range of factors-temperature, redox midpoint potential of an electron carrier, and protein dynamics-on nanosecond electron transfer within a protein. The model reaction was back electron transfer from a bacteriopheophytin anion, HA-, to an oxidized primary electron donor, P+, in a wild type Rhodobacter sphaeroides reaction center (RC) with a permanently reduced secondary electron acceptor (quinone, QA-). Also used were two modified RCs with single amino acid mutations near the monomeric bacteriochlorophyll, BA, located between P and HA. Both mutant RCs showed significant slowing down of this back electron transfer reaction with decreasing temperature, similar to that observed with the wild type RC, but contrasting with a number of single point mutant RCs studied previously. The observed similarities and differences are explained in the framework of a (P+BA- ↔ P+HA-) equilibrium model with an important role played by protein relaxation. The major cause of the observed temperature dependence, both in the wild type RC and in the mutant proteins, is a limitation in access to the thermally activated pathway of charge recombination via the state P+BA- at low temperatures. The data indicate that in all RCs both charge recombination pathways, the thermally activated one and a direct one without involvement of the P+BA- state, are controlled by the protein dynamics. It is concluded that the modifications of the protein environment affect the overall back electron transfer kinetics primarily by changing the redox potential of BA and not by changing the protein relaxation dynamics.
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Affiliation(s)
- Krzysztof Gibasiewicz
- Faculty of Physics, Adam Mickiewicz University, ul. Uniwersytetu Poznańskiego 2, 61-614, Poznań, Poland.
| | - Maria Pajzderska
- Faculty of Physics, Adam Mickiewicz University, ul. Uniwersytetu Poznańskiego 2, 61-614, Poznań, Poland
| | - Rafał Białek
- Faculty of Physics, Adam Mickiewicz University, ul. Uniwersytetu Poznańskiego 2, 61-614, Poznań, Poland
| | - Michael R Jones
- School of Biochemistry, University of Bristol, Medical Sciences BuildingUniversity Walk, Bristol, BS8 1TD, UK
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5
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Exploiting the photoactivity of bacterial reaction center to investigate liposome dynamics. Photochem Photobiol Sci 2021; 20:321-326. [PMID: 33721250 DOI: 10.1007/s43630-021-00011-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 01/08/2021] [Indexed: 10/22/2022]
Abstract
Charge recombination kinetics of bacterial photosynthetic protein Reaction Center displays an exquisite sensitivity to the actual occupancy of ubiquinone-10 in its QB-binding site. Here, we have exploited such phenomenon for assessing the growth and the aggregation/fusion of phosphocholine vesicles embedding RC in their membrane, when treated with sodium oleate.
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6
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Zabelin AA, Khristin AM, Shkuropatova VA, Khatypov RA, Shkuropatov AY. Primary electron transfer in Rhodobacter sphaeroides R-26 reaction centers under dehydration conditions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148238. [PMID: 32533935 DOI: 10.1016/j.bbabio.2020.148238] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 05/28/2020] [Accepted: 06/03/2020] [Indexed: 11/26/2022]
Abstract
The photoinduced charge separation in QB-depleted reaction centers (RCs) from Rhodobacter sphaeroides R-26 in solid air-dried and vacuum-dried (~10-2 Torr) films, obtained in the presence of detergent n-dodecyl-β-D-maltoside (DM), is characterized using ultrafast transient absorption spectroscopy. It is shown that drying of RC-DM complexes is accompanied by reversible blue shifts of the ground-state absorption bands of the pigment ensemble, which suggest that no dehydration-induced structural destruction of RCs occurs in both types of films. In air-dried films, electron transfer from the excited primary electron donor P⁎ to the photoactive bacteriopheophytin HA proceeds in 4.7 ps to form the P+HA- state with essentially 100% yield. P+HA- decays in 260 ps both by electron transfer to the primary quinone QA to give the state P+QA- (87% yield) and by charge recombination to the ground state (13% yield). In vacuum-dried films, P⁎ decay is characterized by two kinetic components with time constants of 4.1 and 46 ps in a proportion of ~55%/45%, and P+HA- decays about 2-fold slower (462 ps) than in air-dried films. Deactivation of both P⁎ and P+HA- to the ground state effectively competes with the corresponding forward electron-transfer reactions in vacuum-dried RCs, reducing the yield of P+QA- to 68%. The results are compared with the data obtained for fully hydrated RCs in solution and are discussed in terms of the presence in the RC complexes of different water molecules, the removal/displacement of which affects spectral properties of pigment cofactors and rates and yields of the electron-transfer reactions.
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Affiliation(s)
- Alexey A Zabelin
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", 142290 Pushchino, Moscow Region, Russian Federation
| | - Anton M Khristin
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", 142290 Pushchino, Moscow Region, Russian Federation
| | - Valentina A Shkuropatova
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", 142290 Pushchino, Moscow Region, Russian Federation
| | - Ravil A Khatypov
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", 142290 Pushchino, Moscow Region, Russian Federation
| | - Anatoly Ya Shkuropatov
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", 142290 Pushchino, Moscow Region, Russian Federation.
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Gorka M, Cherepanov DA, Semenov AY, Golbeck JH. Control of electron transfer by protein dynamics in photosynthetic reaction centers. Crit Rev Biochem Mol Biol 2020; 55:425-468. [PMID: 32883115 DOI: 10.1080/10409238.2020.1810623] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Trehalose and glycerol are low molecular mass sugars/polyols that have found widespread use in the protection of native protein states, in both short- and long-term storage of biological materials, and as a means of understanding protein dynamics. These myriad uses are often attributed to their ability to form an amorphous glassy matrix. In glycerol, the glass is formed only at cryogenic temperatures, while in trehalose, the glass is formed at room temperature, but only upon dehydration of the sample. While much work has been carried out to elucidate a mechanistic view of how each of these matrices interact with proteins to provide stability, rarely have the effects of these two independent systems been directly compared to each other. This review aims to compile decades of research on how different glassy matrices affect two types of photosynthetic proteins: (i) the Type II bacterial reaction center from Rhodobacter sphaeroides and (ii) the Type I Photosystem I reaction center from cyanobacteria. By comparing aggregate data on electron transfer, protein structure, and protein dynamics, it appears that the effects of these two distinct matrices are remarkably similar. Both seem to cause a "tightening" of the solvation shell when in a glassy state, resulting in severely restricted conformational mobility of the protein and associated water molecules. Thus, trehalose appears to be able to mimic, at room temperature, nearly all of the effects on protein dynamics observed in low temperature glycerol glasses.
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Affiliation(s)
- Michael Gorka
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Dmitry A Cherepanov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia.,A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Alexey Yu Semenov
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia.,A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA.,Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
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8
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1,2H hyperfine spectroscopy and DFT modeling unveil the demethylmenasemiquinone binding mode to E. coli nitrate reductase A (NarGHI). BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148203. [PMID: 32305411 DOI: 10.1016/j.bbabio.2020.148203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 04/06/2020] [Accepted: 04/14/2020] [Indexed: 11/23/2022]
Abstract
The quinol oxidation site QD in E. coli respiratory nitrate reductase A (EcNarGHI) reacts with the three isoprenoid quinones naturally synthesized by the bacterium, i.e. ubiquinones (UQ), menaquinones (MK) and demethylmenaquinones (DMK). The binding mode of the demethylmenasemiquinone (DMSK) intermediate to the EcNarGHI QD quinol oxidation site is analyzed in detail using 1,2H hyperfine (hf) spectroscopy in combination with H2O/D2O exchange experiments and DFT modeling, and compared to the menasemiquinone one bound to the QD site (MSKD) previously studied by us. DMSKD and MSKD are shown to bind in a similar and strongly asymmetric manner through a short (~1.7 Å) H-bond. The origin of the specific hf pattern resolved on the DMSKD field-swept EPR spectrum is unambiguously ascribed to slightly inequivalent contributions from two β-methylene protons of the isoprenoid side chain. DFT calculations show that their large isotropic hf coupling constants (Aiso ~12 and 15 MHz) are consistent with both (i) a specific highly asymmetric binding mode of DMSKD and (ii) a near in-plane orientation of its isoprenyl chain at Cβ relative to the aromatic ring, which differs by ~90° to that predicted for free or NarGHI-bound MSK. Our results provide new insights into how the conformation and the redox properties of different natural quinones are selectively fine-tuned by the protein environment at a single Q site. Such a fine-tuning most likely contributes to render NarGHI as an efficient and flexible respiratory enzyme to be used upon rapid variations of the Q-pool content.
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Bielytskyi P, Gräsing D, Zahn S, Mote KR, Alia A, Madhu PK, Matysik J. Assignment of NMR resonances of protons covalently bound to photochemically active cofactors in photosynthetic reaction centers by 13C- 1H photo-CIDNP MAS-J-HMQC experiment. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 298:64-76. [PMID: 30529893 DOI: 10.1016/j.jmr.2018.11.013] [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: 11/02/2018] [Revised: 11/27/2018] [Accepted: 11/28/2018] [Indexed: 06/09/2023]
Abstract
Modified versions of through-bond heteronuclear correlation (HETCOR) experiments are presented to take advantage of the light-induced hyperpolarization that occurs on 13C nuclei due to the solid-state photochemically induced dynamic nuclear polarization (photo-CIDNP) effect. Such 13C-1H photo-CIDNP MAS-J-HMQC and photo-CIDNP MAS-J-HSQC experiments are applied to acquire the 2D 13C-1H correlation spectra of selectively 13C-labeled photochemically active cofactors in the frozen quinone-blocked photosynthetic reaction center (RC) of the purple bacterium Rhodobacter (R.) sphaeroides wild-type (WT). Resulting spectra contain no correlation peaks arising from the protein backbone, which greatly simplifies the assignment of aliphatic region. Based on the photo-CIDNP MAS-J-HMQC NMR experiment, we obtained assignment of selective 1H NMR resonances of the cofactors involved in the electron transfer process in the RC and compared them with values theoretically predicted by density functional theory (DFT) calculation as well as with the chemical shifts obtained from monomeric cofactors in the solution. We also compared proton chemical shifts obtained by photo-CIDNP MAS-J-HMQC experiment under continuous illumination with the ones obtained in dark by classical cross-polarization (CP) HETCOR. We expect that the proposed approach will become a method of choice for obtaining 1H chemical shift maps of the active cofactors in photosynthetic RCs and will aid the interpretation of heteronuclear spin-torch experiments.
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Affiliation(s)
- Pavlo Bielytskyi
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, D-04103 Leipzig, Germany
| | - Daniel Gräsing
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, D-04103 Leipzig, Germany
| | - Stefan Zahn
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, D-04318 Leipzig, Germany
| | - Kaustubh R Mote
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, 36/P Gopanpally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad 500107, India
| | - A Alia
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2301 RA Leiden, the Netherlands; Institut für Medizinische Physik und Biophysik, Universität Leipzig, Härtelstr. 16-18, D-04107 Leipzig, Germany
| | - P K Madhu
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, 36/P Gopanpally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad 500107, India
| | - Jörg Matysik
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, D-04103 Leipzig, Germany.
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Ragni R, Leone G, la Gatta S, Rizzo G, Lo Presti M, De Leo V, Milano F, Trotta M, Farinola GM. A heptamethine cyanine dye suitable as antenna in biohybrids based on bacterial photosynthetic reaction center. ACTA ACUST UNITED AC 2018. [DOI: 10.1557/adv.2018.640] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Mandal S, Espiritu E, Akram N, Lin S, Williams JC, Allen JP, Woodbury NW. Influence of the Electrochemical Properties of the Bacteriochlorophyll Dimer on Triplet Energy-Transfer Dynamics in Bacterial Reaction Centers. J Phys Chem B 2018; 122:10097-10107. [PMID: 30351114 DOI: 10.1021/acs.jpcb.8b07985] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Energetics, protein dynamics, and electronic coupling are the key factors in controlling both electron and energy transfer in photosynthetic bacterial reaction centers (RCs). Here, we examine the rates and mechanistic pathways of the P+HA- radical-pair charge recombination, triplet state formation, and subsequent triplet energy transfer from the triplet state of the bacteriochlorophyll dimer (P) to the carotenoid in a series of mutant RCs (L131LH + M160LH (D1), L131LH + M197FH (D2), and L131LH + M160LH + M197FH (T1)) of Rhodobacter sphaeroides. In these mutants, the electronic structure of P is perturbed and the P/P+ midpoint potential is systematically increased due to addition of hydrogen bonds between P and the introduced residues. High-resolution, broad-band, transient absorption spectroscopy on the femtosecond to microsecond timescale shows that the charge recombination rate increases and the triplet energy transfer rate decreases in these mutants relative to the wild type (WT). The increase of the charge recombination rate is correlated to the increase in the energy level of P+HA- and the increase in the P/P+ midpoint potential. On the other hand, the decrease in rate of triplet energy transfer in the mutants can be explained in terms of a lower energy of 3P and a shift in the electron spin density distribution in the bacteriochlorophylls of P. The triplet energy-transfer rate follows the order of WT > L131LH + M197FH > L131LH + M160LH > L131LH + M160LH + M197FH, both at room temperature and at 77 K. A pronounced temperature dependence of the rate is observed for all of the RC samples. The activation energy associated to this process is increased in the mutants relative to WT, consistent with a lower 3P energy due to the addition of hydrogen bonds between P and the introduced residues.
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12
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Schulz CE, Dutta AK, Izsák R, Pantazis DA. Systematic High-Accuracy Prediction of Electron Affinities for Biological Quinones. J Comput Chem 2018; 39:2439-2451. [PMID: 30281169 DOI: 10.1002/jcc.25570] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Revised: 08/06/2018] [Accepted: 08/07/2018] [Indexed: 11/07/2022]
Abstract
Quinones play vital roles as electron carriers in fundamental biological processes; therefore, the ability to accurately predict their electron affinities is crucial for understanding their properties and function. The increasing availability of cost-effective implementations of correlated wave function methods for both closed-shell and open-shell systems offers an alternative to density functional theory approaches that have traditionally dominated the field despite their shortcomings. Here, we define a benchmark set of quinones with experimentally available electron affinities and evaluate a range of electronic structure methods, setting a target accuracy of 0.1 eV. Among wave function methods, we test various implementations of coupled cluster (CC) theory, including local pair natural orbital (LPNO) approaches to canonical and parameterized CCSD, the domain-based DLPNO approximation, and the equations-of-motion approach for electron affinities, EA-EOM-CCSD. In addition, several variants of canonical, spin-component-scaled, orbital-optimized, and explicitly correlated (F12) Møller-Plesset perturbation theory are benchmarked. Achieving systematically the target level of accuracy is challenging and a composite scheme that combines canonical CCSD(T) with large basis set LPNO-based extrapolation of correlation energy proves to be the most accurate approach. Methods that offer comparable performance are the parameterized LPNO-pCCSD, the DLPNO-CCSD(T0 ), and the orbital optimized OO-SCS-MP2. Among DFT methods, viable practical alternatives are only the M06 and the double hybrids, but the latter should be employed with caution because of significant basis set sensitivity. A highly accurate yet cost-effective DLPNO-based coupled cluster approach is used to investigate the methoxy conformation effect on the electron affinities of ubiquinones found in photosynthetic bacterial reaction centers. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Christine E Schulz
- Fakultät für Chemie und Biochemie, Ruhr-Universität Bochum, 44780, Bochum, Germany
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Achintya Kumar Dutta
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Róbert Izsák
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Dimitrios A Pantazis
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, 45470, Mülheim an der Ruhr, Germany
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
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13
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Okamura MY, Lubitz W, Allen JP. Remembering George Feher (1924-2017). PHOTOSYNTHESIS RESEARCH 2018; 137:361-375. [PMID: 29802563 DOI: 10.1007/s11120-018-0517-9] [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: 05/04/2018] [Accepted: 05/08/2018] [Indexed: 06/08/2023]
Abstract
We provide a tribute to George Feher, one of the founding scientists in the use of biophysical techniques to probe photosynthetic complexes, especially the bacterial reaction center. His early life is briefly reviewed followed by a description of the impact of his 30 years of photosynthesis research. We describe his pioneering work in bacterial photosynthesis that helped to provide a detailed picture of the molecular events responsible for light energy capture and the subsequent electron and proton transfer events in photosynthetic organisms. These studies had a profound and lasting impact on our understanding of the molecular mechanisms of photosynthesis. We also include some personal comments from his former students and colleagues.
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Affiliation(s)
- Melvin Y Okamura
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Wolfgang Lubitz
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470, Mülheim an der Ruhr, Germany
| | - James P Allen
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
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14
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Bielytskyi P, Gräsing D, Mote KR, Sai Sankar Gupta KB, Vega S, Madhu PK, Alia A, Matysik J. 13C → 1H transfer of light-induced hyperpolarization allows for selective detection of protons in frozen photosynthetic reaction center. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 293:82-91. [PMID: 29909081 DOI: 10.1016/j.jmr.2018.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 06/06/2018] [Accepted: 06/07/2018] [Indexed: 05/14/2023]
Abstract
In the present study, we exploit the light-induced hyperpolarization occurring on 13C nuclei due to the solid-state photochemically induced dynamic nuclear polarization (photo-CIDNP) effect to boost the NMR signal intensity of selected protons via inverse cross-polarization. Such hyperpolarization transfer is implemented into 1H-detected two-dimensional 13C-1H correlation magic-angle-spinning (MAS) NMR experiment to study protons in frozen photosynthetic reaction centers (RCs). As a first trial, the performance of such an experiment is tested on selectively 13C labeled RCs from the purple bacteria of Rhodobacter sphaeroides. We observed response from the protons belonging to the photochemically active cofactors in their native protein environment. Such an approach is a potential heteronuclear spin-torch experiment which could be complementary to the classical heteronuclear correlation (HETCOR) experiments for mapping proton chemical shifts of photosynthetic cofactors and to understand the role of the proton pool around the electron donors in the electron transfer process occurring during photosynthesis.
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Affiliation(s)
- Pavlo Bielytskyi
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, D-04103 Leipzig, Germany
| | - Daniel Gräsing
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, D-04103 Leipzig, Germany
| | - Kaustubh R Mote
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, 36/P Gopanpally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad 500107, India
| | | | - Shimon Vega
- Department of Chemical Physics, Weizmann Institute of Science, 76100 Rechovot, Israel
| | - P K Madhu
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, 36/P Gopanpally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad 500107, India; Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - A Alia
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2301 RA Leiden, The Netherlands; Institut für Medizinische Physik und Biophysik, Universität Leipzig, Härtelstr. 16-18, D-04107 Leipzig, Germany
| | - Jörg Matysik
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, D-04103 Leipzig, Germany.
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15
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Sipka G, Kis M, Maróti P. Characterization of mercury(II)-induced inhibition of photochemistry in the reaction center of photosynthetic bacteria. PHOTOSYNTHESIS RESEARCH 2018; 136:379-392. [PMID: 29285578 DOI: 10.1007/s11120-017-0474-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 12/20/2017] [Indexed: 06/07/2023]
Abstract
Mercuric contamination of aqueous cultures results in impairment of viability of photosynthetic bacteria primarily by inhibition of the photochemistry of the reaction center (RC) protein. Isolated reaction centers (RCs) from Rhodobacter sphaeroides were exposed to Hg2+ ions up to saturation concentration (~ 103 [Hg2+]/[RC]) and the gradual time- and concentration-dependent loss of the photochemical activity was monitored. The vast majority of Hg2+ ions (about 500 [Hg2+]/[RC]) had low affinity for the RC [binding constant Kb ~ 5 mM-1] and only a few (~ 1 [Hg2+]/[RC]) exhibited strong binding (Kb ~ 50 μM-1). Neither type of binding site had specific and harmful effects on the photochemistry of the RC. The primary charge separation was preserved even at saturation mercury(II) concentration, but essential further steps of stabilization and utilization were blocked already in the 5 < [Hg2+]/[RC] < 50 range whose locations were revealed. (1) The proton gate at the cytoplasmic site had the highest affinity for Hg2+ binding (Kb ~ 0.2 μM-1) and blocked the proton uptake. (2) Reduced affinity (Kb ~ 0.05 μM-1) was measured for the mercury(II)-binding site close to the secondary quinone that resulted in inhibition of the interquinone electron transfer. (3) A similar affinity was observed close to the bacteriochlorophyll dimer causing slight energetic changes as evidenced by a ~ 30 nm blue shift of the red absorption band, a 47 meV increase in the redox midpoint potential, and a ~ 20 meV drop in free energy gap of the primary charge pair. The primary quinone was not perturbed upon mercury(II) treatment. Although the Hg2+ ions attack the RC in large number, the exertion of the harmful effect on photochemistry is not through mass action but rather a couple of well-defined targets. Bound to these sites, the Hg2+ ions can destroy H-bond structures, inhibit protein dynamics, block conformational gating mechanisms, and modify electrostatic profiles essential for electron and proton transfer.
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Affiliation(s)
- Gábor Sipka
- Department of Medical Physics, University of Szeged, Rerrich Béla tér 1, Szeged, 6720, Hungary
- Department of Plant Biology, Hungarian Academy of Science, Biological Research Centre, Szeged, Hungary
| | - Mariann Kis
- Department of Medical Physics, University of Szeged, Rerrich Béla tér 1, Szeged, 6720, Hungary
| | - Péter Maróti
- Department of Medical Physics, University of Szeged, Rerrich Béla tér 1, Szeged, 6720, Hungary.
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16
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Noji T, Matsuo M, Takeda N, Sumino A, Kondo M, Nango M, Itoh S, Dewa T. Lipid-Controlled Stabilization of Charge-Separated States (P+QB–) and Photocurrent Generation Activity of a Light-Harvesting–Reaction Center Core Complex (LH1-RC) from Rhodopseudomonas palustris. J Phys Chem B 2018; 122:1066-1080. [DOI: 10.1021/acs.jpcb.7b09973] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Tomoyasu Noji
- The OCU Advanced Research Institute for Natural Science & Technology (OCARINA), Osaka City University, Sugimoto-cho, Sumiyoshi-ku, Osaka 558−8585, Japan
| | - Mikano Matsuo
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Nobutaka Takeda
- Department
of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Ayumi Sumino
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Masaharu Kondo
- Department
of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Mamoru Nango
- The OCU Advanced Research Institute for Natural Science & Technology (OCARINA), Osaka City University, Sugimoto-cho, Sumiyoshi-ku, Osaka 558−8585, Japan
| | - Shigeru Itoh
- Division
of Material Sciences (Physics), Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464−8602, Japan
| | - Takehisa Dewa
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
- Department
of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
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17
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Taguchi AT, O’Malley PJ, Wraight CA, Dikanov SA. Determination of the Complete Spin Density Distribution in 13C-Labeled Protein-Bound Radical Intermediates Using Advanced 2D Electron Paramagnetic Resonance Spectroscopy and Density Functional Theory. J Phys Chem B 2017; 121:10256-10268. [DOI: 10.1021/acs.jpcb.7b10036] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alexander T. Taguchi
- Center
for Biophysics and Computational Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
- Department
of Veterinary Clinical Medicine, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | | | - Colin A. Wraight
- Center
for Biophysics and Computational Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
- Department
of Biochemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Sergei A. Dikanov
- Department
of Veterinary Clinical Medicine, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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18
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Najdanova M, Gräsing D, Alia A, Matysik J. Analysis of the Electronic Structure of the Special Pair of a Bacterial Photosynthetic Reaction Center by 13 C Photochemically Induced Dynamic Nuclear Polarization Magic-Angle Spinning NMR Using a Double-Quantum Axis. Photochem Photobiol 2017; 94:69-80. [PMID: 28746728 DOI: 10.1111/php.12812] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/04/2017] [Indexed: 11/28/2022]
Abstract
The origin of the functional symmetry break in bacterial photosynthesis challenges since several decades. Although structurally very similar, the two branches of cofactors in the reaction center (RC) protein complex act very differently. Upon photochemical excitation, an electron is transported along one branch, while the other remains inactive. Photochemically induced dynamic nuclear polarization (photo-CIDNP) magic-angle spinning (MAS) 13 C NMR revealed that the two bacteriochlorophyll cofactors forming the "Special Pair" donor dimer are already well distinguished in the electronic ground state. These previous studies are relying solely on 13 C-13 C correlation experiments as radio-frequency-driven recoupling (RFDR) and dipolar-assisted rotational resonance (DARR). Obviously, the chemical-shift assignment is difficult in a dimer of tetrapyrrole macrocycles, having eight pyrrole rings of similar chemical shifts. To overcome this problem, an INADEQUATE type of experiment using a POST C7 symmetry-based approach is applied to selectively isotope-labeled bacterial RC of Rhodobacter (R.) sphaeroides wild type (WT). We, therefore, were able to distinguish unresolved sites of the macromolecular dimer. The obtained chemical-shift pattern is in-line with a concentric assembly of negative charge within the common center of the Special Pair supermolecule in the electronic ground state.
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Affiliation(s)
- Marija Najdanova
- Institute of Analytical Chemistry, University of Leipzig, Leipzig, Germany
| | - Daniel Gräsing
- Institute of Analytical Chemistry, University of Leipzig, Leipzig, Germany
| | - A Alia
- Institute of Medical Physics and Biophysics, University of Leipzig, Leipzig, Germany.,Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Jörg Matysik
- Institute of Analytical Chemistry, University of Leipzig, Leipzig, Germany
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19
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Mandal S, Carey AM, Locsin J, Gao BR, Williams JC, Allen JP, Lin S, Woodbury NW. Mechanism of Triplet Energy Transfer in Photosynthetic Bacterial Reaction Centers. J Phys Chem B 2017; 121:6499-6510. [DOI: 10.1021/acs.jpcb.7b03373] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Sarthak Mandal
- Center
for Innovations in Medicine, The Biodesign Institute at ASU, Arizona State University, Tempe, Arizona 85287, United States
| | - Anne-Marie Carey
- Center
for Innovations in Medicine, The Biodesign Institute at ASU, Arizona State University, Tempe, Arizona 85287, United States
| | - Joshua Locsin
- Center
for Innovations in Medicine, The Biodesign Institute at ASU, Arizona State University, Tempe, Arizona 85287, United States
| | | | - JoAnn C. Williams
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287−1604, United States
| | - James P. Allen
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287−1604, United States
| | - Su Lin
- Center
for Innovations in Medicine, The Biodesign Institute at ASU, Arizona State University, Tempe, Arizona 85287, United States
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287−1604, United States
| | - Neal W. Woodbury
- Center
for Innovations in Medicine, The Biodesign Institute at ASU, Arizona State University, Tempe, Arizona 85287, United States
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287−1604, United States
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20
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Sun C, Carey AM, Gao BR, Wraight CA, Woodbury NW, Lin S. Ultrafast Electron Transfer Kinetics in the LM Dimer of Bacterial Photosynthetic Reaction Center from Rhodobacter sphaeroides. J Phys Chem B 2016; 120:5395-404. [PMID: 27243380 DOI: 10.1021/acs.jpcb.6b05082] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
It has become increasingly clear that dynamics plays a major role in the function of many protein systems. One system that has proven particularly facile for studying the effects of dynamics on protein-mediated chemistry is the bacterial photosynthetic reaction center from Rhodobacter sphaeroides. Previous experimental and computational analysis have suggested that the dynamics of the protein matrix surrounding the primary quinone acceptor, QA, may be particularly important in electron transfer involving this cofactor. One can substantially increase the flexibility of this region by removing one of the reaction center subunits, the H-subunit. Even with this large change in structure, photoinduced electron transfer to the quinone still takes place. To evaluate the effect of H-subunit removal on electron transfer to QA, we have compared the kinetics of electron transfer and associated spectral evolution for the LM dimer with that of the intact reaction center complex on picosecond to millisecond time scales. The transient absorption spectra associated with all measured electron transfer reactions are similar, with the exception of a broadening in the QX transition and a blue-shift in the QY transition bands of the special pair of bacteriochlorophylls (P) in the LM dimer. The kinetics of the electron transfer reactions not involving quinones are unaffected. There is, however, a 4-fold decrease in the electron transfer rate from the reduced bacteriopheophytin to QA in the LM dimer compared to the intact reaction center and a similar decrease in the recombination rate of the resulting charge-separated state (P(+)QA(-)). These results are consistent with the concept that the removal of the H-subunit results in increased flexibility in the region around the quinone and an associated shift in the reorganization energy associated with charge separation and recombination.
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Affiliation(s)
- Chang Sun
- Department of Biochemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | | | - Bing-Rong Gao
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University , Jilin, China 130012
| | - Colin A Wraight
- Department of Biochemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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21
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Gibasiewicz K, Białek R, Pajzderska M, Karolczak J, Burdziński G, Jones MR, Brettel K. Weak temperature dependence of P (+) H A (-) recombination in mutant Rhodobacter sphaeroides reaction centers. PHOTOSYNTHESIS RESEARCH 2016; 128:243-258. [PMID: 26942583 PMCID: PMC4877430 DOI: 10.1007/s11120-016-0239-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 02/24/2016] [Indexed: 06/05/2023]
Abstract
In contrast with findings on the wild-type Rhodobacter sphaeroides reaction center, biexponential P (+) H A (-) → PH A charge recombination is shown to be weakly dependent on temperature between 78 and 298 K in three variants with single amino acids exchanged in the vicinity of primary electron acceptors. These mutated reaction centers have diverse overall kinetics of charge recombination, spanning an average lifetime from ~2 to ~20 ns. Despite these differences a protein relaxation model applied previously to wild-type reaction centers was successfully used to relate the observed kinetics to the temporal evolution of the free energy level of the state P (+) H A (-) relative to P (+) B A (-) . We conclude that the observed variety in the kinetics of charge recombination, together with their weak temperature dependence, is caused by a combination of factors that are each affected to a different extent by the point mutations in a particular mutant complex. These are as follows: (1) the initial free energy gap between the states P (+) B A (-) and P (+) H A (-) , (2) the intrinsic rate of P (+) B A (-) → PB A charge recombination, and (3) the rate of protein relaxation in response to the appearance of the charge separated states. In the case of a mutant which displays rapid P (+) H A (-) recombination (ELL), most of this recombination occurs in an unrelaxed protein in which P (+) B A (-) and P (+) H A (-) are almost isoenergetic. In contrast, in a mutant in which P (+) H A (-) recombination is relatively slow (GML), most of the recombination occurs in a relaxed protein in which P (+) H A (-) is much lower in energy than P (+) H A (-) . The weak temperature dependence in the ELL reaction center and a YLH mutant was modeled in two ways: (1) by assuming that the initial P (+) B A (-) and P (+) H A (-) states in an unrelaxed protein are isoenergetic, whereas the final free energy gap between these states following the protein relaxation is large (~250 meV or more), independent of temperature and (2) by assuming that the initial and final free energy gaps between P (+) B A (-) and P (+) H A (-) are moderate and temperature dependent. In the case of the GML mutant, it was concluded that the free energy gap between P (+) B A (-) and P (+) H A (-) is large at all times.
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Affiliation(s)
- Krzysztof Gibasiewicz
- Department of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614, Poznań, Poland.
| | - Rafał Białek
- Department of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614, Poznań, Poland
| | - Maria Pajzderska
- Department of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614, Poznań, Poland
| | - Jerzy Karolczak
- Department of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614, Poznań, Poland
- Center for Ultrafast Laser Spectroscopy, A. Mickiewicz University, ul. Umultowska 85, 61-614, Poznań, Poland
| | - Gotard Burdziński
- Department of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614, Poznań, Poland
| | - Michael R Jones
- School of Biochemistry, Medical Sciences Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Klaus Brettel
- Laboratoire Mécanismes Fondamentaux de la Bioénergétique, UMR 8221, CEA - iBiTec-S, CNRS, Université Paris Sud, 91191, Gif-Sur-Yvette, France
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22
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Szabó T, Magyar M, Hajdu K, Dorogi M, Nyerki E, Tóth T, Lingvay M, Garab G, Hernádi K, Nagy L. Structural and Functional Hierarchy in Photosynthetic Energy Conversion-from Molecules to Nanostructures. NANOSCALE RESEARCH LETTERS 2015; 10:458. [PMID: 26619890 PMCID: PMC4666181 DOI: 10.1186/s11671-015-1173-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Accepted: 11/23/2015] [Indexed: 06/05/2023]
Abstract
Basic principles of structural and functional requirements of photosynthetic energy conversion in hierarchically organized machineries are reviewed. Blueprints of photosynthesis, the energetic basis of virtually all life on Earth, can serve the basis for constructing artificial light energy-converting molecular devices. In photosynthetic organisms, the conversion of light energy into chemical energy takes places in highly organized fine-tunable systems with structural and functional hierarchy. The incident photons are absorbed by light-harvesting complexes, which funnel the excitation energy into reaction centre (RC) protein complexes containing redox-active chlorophyll molecules; the primary charge separations in the RCs are followed by vectorial transport of charges (electrons and protons) in the photosynthetic membrane. RCs possess properties that make their use in solar energy-converting and integrated optoelectronic systems feasible. Therefore, there is a large interest in many laboratories and in the industry toward their use in molecular devices. RCs have been bound to different carrier matrices, with their photophysical and photochemical activities largely retained in the nano-systems and with electronic connection to conducting surfaces. We show examples of RCs bound to carbon-based materials (functionalized and non-functionalized single- and multiwalled carbon nanotubes), transitional metal oxides (ITO) and conducting polymers and porous silicon and characterize their photochemical activities. Recently, we adapted several physical and chemical methods for binding RCs to different nanomaterials. It is generally found that the P(+)(QAQB)(-) charge pair, which is formed after single saturating light excitation is stabilized after the attachment of the RCs to the nanostructures, which is followed by slow reorganization of the protein structure. Measuring the electric conductivity in a direct contact mode or in electrochemical cell indicates that there is an electronic interaction between the protein and the inorganic carrier matrices. This can be a basis of sensing element of bio-hybrid device for biosensor and/or optoelectronic applications.
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Affiliation(s)
- Tibor Szabó
- Department of Medical Physics and Informatics, University of Szeged, Rerrich B. tér 1., H-6721, Szeged, Hungary.
| | - Melinda Magyar
- Department of Medical Physics and Informatics, University of Szeged, Rerrich B. tér 1., H-6721, Szeged, Hungary.
| | - Kata Hajdu
- Department of Medical Physics and Informatics, University of Szeged, Rerrich B. tér 1., H-6721, Szeged, Hungary.
| | - Márta Dorogi
- Biological Research Center, Hungarian Academy of Sciences, Temesvari krt.62, H-6726, Szeged, Hungary.
- Biophotonics R&D Ltd., Temesvari krt.62, H-6726, Szeged, Hungary.
| | - Emil Nyerki
- Department of Medical Physics and Informatics, University of Szeged, Rerrich B. tér 1., H-6721, Szeged, Hungary.
| | - Tünde Tóth
- Department of Medical Physics and Informatics, University of Szeged, Rerrich B. tér 1., H-6721, Szeged, Hungary.
| | - Mónika Lingvay
- Department of Medical Physics and Informatics, University of Szeged, Rerrich B. tér 1., H-6721, Szeged, Hungary.
| | - Győző Garab
- Biological Research Center, Hungarian Academy of Sciences, Temesvari krt.62, H-6726, Szeged, Hungary.
- Biophotonics R&D Ltd., Temesvari krt.62, H-6726, Szeged, Hungary.
| | - Klára Hernádi
- Department of Applied and Environmental Chemistry, University of Szeged, Szeged, Hungary.
| | - László Nagy
- Department of Medical Physics and Informatics, University of Szeged, Rerrich B. tér 1., H-6721, Szeged, Hungary.
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23
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Nagy L, Kiss V, Brumfeld V, Osvay K, Börzsönyi Á, Magyar M, Szabó T, Dorogi M, Malkin S. Thermal Effects and Structural Changes of Photosynthetic Reaction Centers Characterized by Wide Frequency Band Hydrophone: Effects of Carotenoids and Terbutryn. Photochem Photobiol 2015; 91:1368-75. [PMID: 26277346 DOI: 10.1111/php.12511] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Accepted: 08/06/2015] [Indexed: 11/30/2022]
Affiliation(s)
- László Nagy
- Department of Medical Physics and Informatics; University of Szeged; Szeged Hungary
| | - Vladimir Kiss
- Department of Biological Chemistry; Weizmann Institute of Science; Rehovot Israel
| | - Vlad Brumfeld
- Department of Chemical Research Support; Weizmann Institute of Science; Rehovot Israel
| | - Károly Osvay
- Department of Optics and Quantum Electronics; University of Szeged; Szeged Hungary
| | - Ádám Börzsönyi
- Department of Optics and Quantum Electronics; University of Szeged; Szeged Hungary
| | - Melinda Magyar
- Department of Medical Physics and Informatics; University of Szeged; Szeged Hungary
| | - Tibor Szabó
- Department of Medical Physics and Informatics; University of Szeged; Szeged Hungary
| | - Márta Dorogi
- Biophotonics R&D Ltd; Szeged Hungary
- Institute of Plant Biology; Biological Research Center; Hungarian Academy of Sciences; Szeged Hungary
| | - Shmuel Malkin
- Department of Biological Chemistry; Weizmann Institute of Science; Rehovot Israel
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24
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Kimura Y, Kawakami T, Yu LJ, Yoshimura M, Kobayashi M, Wang-Otomo ZY. Characterization of the quinones in purple sulfur bacteriumThermochromatium tepidum. FEBS Lett 2015; 589:1761-5. [DOI: 10.1016/j.febslet.2015.05.043] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 05/21/2015] [Accepted: 05/22/2015] [Indexed: 11/27/2022]
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25
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Maróti Á, Wraight CA, Maróti P. Protonated rhodosemiquinone at the Q(B) binding site of the M265IT mutant reaction center of photosynthetic bacterium Rhodobacter sphaeroides. Biochemistry 2015; 54:2095-103. [PMID: 25760888 DOI: 10.1021/bi501553t] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The second electron transfer from primary ubiquinone Q(A) to secondary ubiquinone Q(B) in the reaction center (RC) from Rhodobacter sphaeroides involves a protonated Q(B)(-) intermediate state whose low pK(a) makes direct observation impossible. Here, we replaced the native ubiquinone with low-potential rhodoquinone at the Q(B) binding site of the M265IT mutant RC. Because the in situ midpoint redox potential of Q(A) of this mutant was lowered approximately the same extent (≈100 mV) as that of Q(B) upon exchange of ubiquinone with low-potential rhodoquinone, the inter-quinone (Q(A) → Q(B)) electron transfer became energetically favorable. After subsequent saturating flash excitations, a period of two damped oscillations of the protonated rhodosemiquinone was observed. The Q(B)H(•) was identified by (1) the characteristic band at 420 nm of the absorption spectrum after the second flash and (2) weaker damping of the oscillation at 420 nm (due to the neutral form) than at 460 nm (attributed to the anionic form). The appearance of the neutral semiquinone was restricted to the acidic pH range, indicating a functional pK(a) of <5.5, slightly higher than that of the native ubisemiquinone (pK(a) < 4.5) at pH 7. The analysis of the pH and temperature dependencies of the rates of the second electron transfer supports the concept of the pH-dependent pK(a) of the semiquinone at the Q(B) binding site. The local electrostatic potential is severely modified by the strongly interacting neighboring acidic cluster, and the pK(a) of the semiquinone is in the middle of the pH range of the complex titration. The kinetic and thermodynamic data are discussed according to the proton-activated electron transfer mechanism combined with the pH-dependent functional pK(a) of the semiquinone at the Q(B) site of the RC.
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Affiliation(s)
| | - Colin A Wraight
- §Center for Biophysics and Computational Biology and Department of Plant Biology, University of Illinois, Urbana, Illinois 61801-3838, United States
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Vermaas JV, Taguchi AT, Dikanov SA, Wraight CA, Tajkhorshid E. Redox potential tuning through differential quinone binding in the photosynthetic reaction center of Rhodobacter sphaeroides. Biochemistry 2015; 54:2104-16. [PMID: 25734689 DOI: 10.1021/acs.biochem.5b00033] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ubiquinone forms an integral part of the electron transport chain in cellular respiration and photosynthesis across a vast number of organisms. Prior experimental results have shown that the photosynthetic reaction center (RC) from Rhodobacter sphaeroides is only fully functional with a limited set of methoxy-bearing quinones, suggesting that specific interactions with this substituent are required to drive electron transport and the formation of quinol. The nature of these interactions has yet to be determined. Through parameterization of a CHARMM-compatible quinone force field and subsequent molecular dynamics simulations of the quinone-bound RC, we have investigated and characterized the interactions of the protein with the quinones in the Q(A) and Q(B) sites using both equilibrium simulation and thermodynamic integration. In particular, we identify a specific interaction between the 2-methoxy group of ubiquinone in the Q(B) site and the amide nitrogen of GlyL225 that we implicate in locking the orientation of the 2-methoxy group, thereby tuning the redox potential difference between the quinones occupying the Q(A) and Q(B) sites. Disruption of this interaction leads to weaker binding in a ubiquinone analogue that lacks a 2-methoxy group, a finding supported by reverse electron transfer electron paramagnetic resonance experiments of the Q(A)⁻Q(B)⁻ biradical and competitive binding assays.
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Affiliation(s)
- Josh V Vermaas
- †Center for Biophysics and Computational Biology, ‡Department of Biochemistry, §Beckman Institute, and ∥Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Alexander T Taguchi
- †Center for Biophysics and Computational Biology, ‡Department of Biochemistry, §Beckman Institute, and ∥Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Sergei A Dikanov
- †Center for Biophysics and Computational Biology, ‡Department of Biochemistry, §Beckman Institute, and ∥Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Colin A Wraight
- †Center for Biophysics and Computational Biology, ‡Department of Biochemistry, §Beckman Institute, and ∥Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Emad Tajkhorshid
- †Center for Biophysics and Computational Biology, ‡Department of Biochemistry, §Beckman Institute, and ∥Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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Semiquinone oscillations as a tool for investigating the ubiquinone binding to photosynthetic reaction centers. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 44:183-92. [DOI: 10.1007/s00249-015-1013-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 02/04/2015] [Accepted: 02/05/2015] [Indexed: 01/04/2023]
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Sai Sankar Gupta KB, Daviso E, Jeschke G, Alia A, Ernst M, Matysik J. Spectral editing through laser-flash excitation in two-dimensional photo-CIDNP MAS NMR experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 246:9-17. [PMID: 25063951 DOI: 10.1016/j.jmr.2014.06.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/08/2014] [Accepted: 06/17/2014] [Indexed: 05/14/2023]
Abstract
In solid-state photochemically induced dynamic nuclear polarization (photo-CIDNP) MAS NMR experiments, strong signal enhancement is observed from molecules forming a spin-correlated radical pair in a rigid matrix. Two-dimensional (13)C-(13)C dipolar-assisted rotational resonance (DARR) photo-CIDNP MAS NMR experiments have been applied to obtain exact chemical shift assignments from those cofactors. Under continuous illumination, the signals are enhanced via three-spin mixing (TSM) and differential decay (DD) and their intensity corresponds to the electron spin density in pz orbitals. In multiple-(13)C labelled samples, spin diffusion leads to propagation of signal enhancement to all (13)C spins. Under steady-state conditions, direct signal assignment is possible due to the uniform signal intensity. The original intensities, however, are inaccessible and the information of the local electron spin density is lost. Upon laser-flash illumination, the signal is enhanced via the classical radical pair mechanism (RPM). The obtained intensities are related to isotropic hyperfine interactions aiso and both enhanced absorptive and emissive lines can be observed due to differences in the sign of the local isotropic hyperfine interaction. Exploiting the mechanism of the polarization, selectivity can be increased by the novel time-resolved two-dimensional dipolar-assisted rotational resonance (DARR) MAS NMR experiment which simplifies the signal assignment compared to complex spectra of the same RCs obtained by continuous illumination. Here we present two-dimensional time-resolved photo-CIDNP MAS NMR experiments providing both directly: signal assignment and spectral editing by sign and strength of aiso. Hence, this experiment provides a direct key to the electronic structure of the correlated radical pair.
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Affiliation(s)
| | - Eugenio Daviso
- Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands; Francis Bitter Magnet Laboratory, Albany Street 150, NW14, Cambridge, MA 02139, USA
| | - Gunnar Jeschke
- ETH Zürich, Physical Chemistry, Wolfgang-Pauli-Strasse 10, 8093 Zürich, Switzerland
| | - A Alia
- Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands; Institut für Analytische Chemie, Universität Leipzig, Linnéstr. 3, 04103 Leipzig, Germany
| | - Matthias Ernst
- ETH Zürich, Physical Chemistry, Wolfgang-Pauli-Strasse 10, 8093 Zürich, Switzerland
| | - Jörg Matysik
- Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands; Institut für Analytische Chemie, Universität Leipzig, Linnéstr. 3, 04103 Leipzig, Germany.
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The binding of quinone to the photosynthetic reaction centers: kinetics and thermodynamics of reactions occurring at the QB-site in zwitterionic and anionic liposomes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2014; 43:301-15. [PMID: 24824111 DOI: 10.1007/s00249-014-0963-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 04/07/2014] [Accepted: 04/25/2014] [Indexed: 12/29/2022]
Abstract
Liposomes represent a versatile biomimetic environment for studying the interaction between integral membrane proteins and hydrophobic ligands. In this paper, the quinone binding to the QB-site of the photosynthetic reaction centers (RC) from Rhodobacter sphaeroides has been investigated in liposomes prepared with either the zwitterionic phosphatidylcholine (PC) or the negatively charged phosphatidylglycerol (PG) to highlight the role of the different phospholipid polar heads. Quinone binding (K Q) and interquinone electron transfer (L AB) equilibrium constants in the two type of liposomes were obtained by charge recombination reaction of QB-depleted RC in the presence of increasing amounts of ubiquinone-10 over the temperature interval 6-35 °C. The kinetic of the charge recombination reactions has been fitted by numerically solving the ordinary differential equations set associated with a detailed kinetic scheme involving electron transfer reactions coupled with quinone release and uptake. The entire set of traces at each temperature was accurately fitted using the sole quinone release constants (both in a neutral and a charge separated state) as adjustable parameters. The temperature dependence of the quinone exchange rate at the QB-site was, hence, obtained. It was found that the quinone exchange regime was always fast for PC while it switched from slow to fast in PG as the temperature rose above 20 °C. A new method was introduced in this paper for the evaluation of constant K Q using the area underneath the charge recombination traces as the indicator of the amount of quinone bound to the QB-site.
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Wraight CA. Roderick K. Clayton: a life, and some personal recollections. PHOTOSYNTHESIS RESEARCH 2014; 120:9-26. [PMID: 24254320 DOI: 10.1007/s11120-013-9948-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Accepted: 10/21/2013] [Indexed: 06/02/2023]
Abstract
Roderick K. Clayton passed away on October 23, 2011, at the age of 89, shortly after the plan for this dedicatory issue of Photosynthesis Research had been hatched. I had just written a lengthy letter to him to re-establish contact after a hiatus of 2 or 3 years, and to suggest that I visit him to talk about his life. It isn't clear whether he saw the letter or not, but it was found at his home in Santa Rosa, California. Fortunately, Rod has written two memoirs for Photosynthesis Research that not only cover much of his research on reaction centers (Photosynth Res 73:63-71, 2002) but also provide a humorous and honest look at his personal life (Photosynth Res 19:207-224, 1988). I cannot hope to improve on these and will try, instead, to fill in some of the gaps that Rod's own writing has left, and offer some of my own personal recollections over the more recent years.
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Affiliation(s)
- Colin A Wraight
- Department of Biochemistry and Center for Biophysics & Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA,
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31
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Okamura M, Wraight CA, van Grondelle R. Special issue of photosynthetic research. PHOTOSYNTHESIS RESEARCH 2014; 120:1-2. [PMID: 24287763 DOI: 10.1007/s11120-013-9952-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This Special Issue of Photosynthesis Research honors Louis M. N. Duysens, Roderick K. Clayton, and George Feher, three pioneering researchers whose work on bacterial photosynthesis laid much of the groundwork for our understanding of the role of the reaction center in photosynthetic light energy conversion. Their key discoveries are briefly summarized and an overview of the special issue is presented.
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Yehezkeli O, Tel-Vered R, Michaeli D, Willner I, Nechushtai R. Photosynthetic reaction center-functionalized electrodes for photo-bioelectrochemical cells. PHOTOSYNTHESIS RESEARCH 2014; 120:71-85. [PMID: 23371753 DOI: 10.1007/s11120-013-9796-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Accepted: 01/17/2013] [Indexed: 06/01/2023]
Abstract
During the last few years, intensive research efforts have been directed toward the application of several highly efficient light-harvesting photosynthetic proteins, including reaction centers (RCs), photosystem I (PSI), and photosystem II (PSII), as key components in the light-triggered generation of fuels or electrical power. This review highlights recent advances for the nano-engineering of photo-bioelectrochemical cells through the assembly of the photosynthetic proteins on electrode surfaces. Various strategies to immobilize the photosynthetic complexes on conductive surfaces and different methodologies to electrically wire them with the electrode supports are presented. The different photoelectrochemical systems exhibit a wide range of photocurrent intensities and power outputs that sharply depend on the nano-engineering strategy and the electroactive components. Such cells are promising candidates for a future production of biologically-driven solar power.
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Affiliation(s)
- Omer Yehezkeli
- Institute of Chemistry, The Minerva Center for Biohybrid Systems, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel
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Zhang X, Gunner MR. Affinity and activity of non-native quinones at the Q(B) site of bacterial photosynthetic reaction centers. PHOTOSYNTHESIS RESEARCH 2014; 120:181-96. [PMID: 23715773 PMCID: PMC4442677 DOI: 10.1007/s11120-013-9850-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 05/08/2013] [Indexed: 05/11/2023]
Abstract
Purple, photosynthetic reaction centers from Rhodobacter sphaeroides bacteria use ubiquinone (UQ10) as both primary (Q(A)) and secondary (Q(B)) electron acceptors. Many quinones reconstitute Q(A) function, while a few will act as Q(B). Nine quinones were tested for their ability to bind and reconstitute Q(A) and Q(B) functions. Only ubiquinone (UQ) reconstitutes both functions in the same protein. The affinities of the non-native quinones for the Q(B) site were determined by a competitive inhibition assay. The affinities of benzoquinones, naphthoquinone (NQ), and 2-methyl-NQ for the Q(B) site are 7 ± 3 times weaker than that at Q(A) site. However, di-ortho-substituted NQs and anthraquinone bind tightly to the Q(A) site (K d ≤ 200 nM), and ≥1,000 times more weakly to the Q(B) site, perhaps setting a limit on the size of the site. With a low-potential electron donor, 2-methyl, 3-dimethylamino-1,4-NQ, (Me-diMeAm-NQ) at Q(A), Q(B) reduction is 260 meV, more favorable than with UQ as Q(A). Electron transfer from Me-diMeAm-NQ at the Q(A) site to NQ at the Q(B) site can be detected. In the Q(B) site, the NQ semiquinone is estimated to be ≈60-100 meV higher in energy than the UQ semiquinone, while in the Q(A) site, the semiquinone energy level is similar or lower with NQ than with UQ. Thus, the NQ semiquinone is more stable in the Q(A) than in the Q(B) site. In contrast, the native UQ semiquinone is ≈60 meV lower in energy in the Q(B) than in the Q(A) site, stabilizing forward electron transfer from Q(A) to Q(B).
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Affiliation(s)
| | - M. R. Gunner
- To whom correspondence should be addressed. Telephone: 212-650-5557. Fax: 212-650-6940
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Okamura M. George Feher: a pioneer in reaction center research. PHOTOSYNTHESIS RESEARCH 2014; 120:29-42. [PMID: 24104959 DOI: 10.1007/s11120-013-9927-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 09/16/2013] [Indexed: 06/02/2023]
Abstract
Our understanding of photosynthesis has been greatly advanced by the elucidation of the structure and function of the reaction center (RC), the membrane protein responsible for the initial light-induced charge separation in photosynthetic bacteria and green plants. Although today we know a great deal about the details of the primary processes in photosynthesis, little was known in the early days. George Feher made pioneering contributions to photosynthesis research in characterizing RCs from photosynthetic bacteria following the ground-breaking work of Lou Duysens and Rod Clayton (see articles in this issue by van Gorkom and Wraight). The work in his laboratory at the University of California, San Diego, started in the late 1960s and continued for over 30 years. He isolated a pure RC protein and used magnetic resonance spectroscopy to study the primary reactants. Following this pioneering work, Feher studied the detailed structure of the RC and the basic electron and proton transfer functions that it performs using a wide variety of biophysical and biochemical techniques. These studies, together with work from many other researchers, have led to our present detailed understanding of these proteins and their function in photosynthesis. The present article is a brief historical account of his pioneering contributions to photosynthesis research. A more detailed description of his work can be found in an earlier biographical paper (Feher in Photosynth Res 55:1-40, 1998a).
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Affiliation(s)
- Melvin Okamura
- Department of Physics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0354, USA,
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35
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Bering CL, Bustamante PL, Loach PA. Inhibition of the Primary Photochemical Events inRhodospirillum Rubrumby Ubiquinone Analogues. Isr J Chem 2013. [DOI: 10.1002/ijch.198100047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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36
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Wraight CA. Oxidation-Reduction Physical Chemistry of the Acceptor Quinone Complex in Bacterial Photosynthetic Reaction Centers: Evidence for a New Model of Herbicide Activity. Isr J Chem 2013. [DOI: 10.1002/ijch.198100063] [Citation(s) in RCA: 189] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Müh F, Zouni A. The nonheme iron in photosystem II. PHOTOSYNTHESIS RESEARCH 2013; 116:295-314. [PMID: 24077892 DOI: 10.1007/s11120-013-9926-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 09/17/2013] [Indexed: 06/02/2023]
Abstract
Photosystem II (PSII), the light-driven water:plastoquinone (PQ) oxidoreductase of oxygenic photosynthesis, contains a nonheme iron (NHI) at its electron acceptor side. The NHI is situated between the two PQs QA and QB that serve as one-electron transmitter and substrate of the reductase part of PSII, respectively. Among the ligands of the NHI is a (bi)carbonate originating from CO2, the substrate of the dark reactions of oxygenic photosynthesis. Based on recent advances in the crystallography of PSII, we review the structure of the NHI in PSII and discuss ideas concerning its function and the role of bicarbonate along with a comparison to the reaction center of purple bacteria and other enzymes containing a mononuclear NHI site.
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Gibasiewicz K, Pajzderska M, Dobek A, Karolczak J, Burdziński G, Brettel K, Jones MR. Analysis of the temperature-dependence of P(+)HA(-) charge recombination in the Rhodobacter sphaeroides reaction center suggests nanosecond temperature-independent protein relaxation. Phys Chem Chem Phys 2013; 15:16321-33. [PMID: 23999896 DOI: 10.1039/c3cp44187c] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The temperature dependence of charge recombination of the pair P(+)HA(-) in isolated reaction centers from the purple bacterium Rhodobacter sphaeroides with prereduced quinone QA was studied by sub-nanosecond to microsecond time-scale transient absorption. Overall, the kinetics slowed down substantially upon cooling from room temperature to ∼200 K, and then remained virtually unchanged down to 77 K, indicating the coexistence of two competitive pathways of charge recombination, a thermally-activated pathway appearing only above ~200 K and a temperature-independent pathway. In our modelling, the thermally activated pathway includes an uphill electron transfer from HA(-) to BA(-) leading to transient formation of the state P(+)BA(-), whereas the temperature-independent pathway is due to direct downhill electron transfer from HA(-) to P(+). At all temperatures studied, the kinetics could be approximated by a four-component decay. Detailed analysis of the lifetimes and amplitudes of particular phases over the range of temperatures suggests that the kinetically resolved phases reveal the consecutive appearance of three conformational states characterized by an increasing free energy gap between the states P(+)BA(-) and P(+)HA(-). The initial gap between these states was estimated to be only ~8 meV, the intermediate gap being ~92 meV, and the final gap ~135 meV, with no dependence on temperature. It was also calculated through a very straightforward approach that the relaxation process from the initial to the intermediate state occurs within 0.6 ± 0.1 ns, whereas the second step of relaxation from the intermediate to the final state takes 11 ± 2 ns. Both phases of the protein relaxation process are essentially temperature-independent. Possible alternative models to describe the experimental data that cannot be definitely excluded are also discussed.
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Affiliation(s)
- Krzysztof Gibasiewicz
- Department of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań, Poland.
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Gunner MR, Amin M, Zhu X, Lu J. Molecular mechanisms for generating transmembrane proton gradients. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1827:892-913. [PMID: 23507617 PMCID: PMC3714358 DOI: 10.1016/j.bbabio.2013.03.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/28/2013] [Accepted: 03/01/2013] [Indexed: 01/02/2023]
Abstract
Membrane proteins use the energy of light or high energy substrates to build a transmembrane proton gradient through a series of reactions leading to proton release into the lower pH compartment (P-side) and proton uptake from the higher pH compartment (N-side). This review considers how the proton affinity of the substrates, cofactors and amino acids are modified in four proteins to drive proton transfers. Bacterial reaction centers (RCs) and photosystem II (PSII) carry out redox chemistry with the species to be oxidized on the P-side while reduction occurs on the N-side of the membrane. Terminal redox cofactors are used which have pKas that are strongly dependent on their redox state, so that protons are lost on oxidation and gained on reduction. Bacteriorhodopsin is a true proton pump. Light activation triggers trans to cis isomerization of a bound retinal. Strong electrostatic interactions within clusters of amino acids are modified by the conformational changes initiated by retinal motion leading to changes in proton affinity, driving transmembrane proton transfer. Cytochrome c oxidase (CcO) catalyzes the reduction of O2 to water. The protons needed for chemistry are bound from the N-side. The reduction chemistry also drives proton pumping from N- to P-side. Overall, in CcO the uptake of 4 electrons to reduce O2 transports 8 charges across the membrane, with each reduction fully coupled to removal of two protons from the N-side, the delivery of one for chemistry and transport of the other to the P-side.
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Affiliation(s)
- M R Gunner
- Department of Physics, City College of New York, New York, NY 10031, USA.
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40
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Guo Z, Lin S, Woodbury NW. Utilizing the Dynamic Stark Shift as a Probe for Dielectric Relaxation in Photosynthetic Reaction Centers During Charge Separation. J Phys Chem B 2013; 117:11383-90. [DOI: 10.1021/jp4037843] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Zhi Guo
- The
Biodesign Institute at Arizona State University, ‡Department of Chemistry and Biochemistry, and §Department of
Physics, Arizona State University, Tempe, Arizona 85287-5201, United States
| | - Su Lin
- The
Biodesign Institute at Arizona State University, ‡Department of Chemistry and Biochemistry, and §Department of
Physics, Arizona State University, Tempe, Arizona 85287-5201, United States
| | - Neal W. Woodbury
- The
Biodesign Institute at Arizona State University, ‡Department of Chemistry and Biochemistry, and §Department of
Physics, Arizona State University, Tempe, Arizona 85287-5201, United States
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41
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Sai Sankar Gupta KB, Alia A, de Groot HJ, Matysik J. Symmetry Break of Special Pair: Photochemically Induced Dynamic Nuclear Polarization NMR Confirms Control by Nonaromatic Substituents. J Am Chem Soc 2013; 135:10382-7. [DOI: 10.1021/ja402238w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - A. Alia
- Institute
of Chemistry, Leiden University, P.O. Box
9502, 2300 RA Leiden, The
Netherlands
- Institut für Medizinische
Physik und Biophysik, Universität Leipzig, Härtelstraße 16-18, 04107 Leipzig, Germany
| | - Huub J.M. de Groot
- Institute
of Chemistry, Leiden University, P.O. Box
9502, 2300 RA Leiden, The
Netherlands
| | - Jörg Matysik
- Institute
of Chemistry, Leiden University, P.O. Box
9502, 2300 RA Leiden, The
Netherlands
- Institut für
Analytische
Chemie, Universität Leipzig, Linnèstr.
3, 04104 Leipzig, Germany
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42
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Narth C, Gillet N, Lévy B, Demachy I, de la Lande A. Investigation of the molecular mechanisms of electronic decoherence within a quinone cofactor. CAN J CHEM 2013. [DOI: 10.1139/cjc-2012-0529] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The notion of decoherence is particularly adapted to discuss the quantum-to-classical transition in the context of chemical reactions. Decoherence can be modeled by computing the time evolution of nuclear wave packets evolving on distinct potential energy surfaces, here using density functional theory (DFT) and Born–Oppenheimer molecular dynamics simulations. We investigate a redox cofactor of biological interest (tryptophan tryptophylquinone, TTQ) found in the enzyme methylamine dehydrogenase. We also report the first systematic comparison of semi-empirical DFT (tight-binding DFT) and classical force field approaches for estimating decoherence in molecular systems. In the TTQ cofactor, we find that decoherence combines structural and dynamical aspects: it is initiated by the divergent motions of few atoms and then propagates dynamically to the remaining atoms. It is the mass effect of all the atoms that leads to decoherence within a few femtosecond.
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Affiliation(s)
- Christophe Narth
- Laboratoire de Chimie-Physique, CNRS UMR 8000, Université Paris Sud, Bâtiment 349 - Campus d’Orsay, 15, avenue Jean Perrin, 91 405 Orsay Cedex, France
- Laboratoire de Chimie Théorique, CNRS UMR 7616, Université Pierre et Marie Curie, case courrier 137, 4, Place Jussieu, 75 252 Paris Cedex 05, France
| | - Natacha Gillet
- Laboratoire de Chimie-Physique, CNRS UMR 8000, Université Paris Sud, Bâtiment 349 - Campus d’Orsay, 15, avenue Jean Perrin, 91 405 Orsay Cedex, France
| | - Bernard Lévy
- Laboratoire de Chimie-Physique, CNRS UMR 8000, Université Paris Sud, Bâtiment 349 - Campus d’Orsay, 15, avenue Jean Perrin, 91 405 Orsay Cedex, France
| | - Isabelle Demachy
- Laboratoire de Chimie-Physique, CNRS UMR 8000, Université Paris Sud, Bâtiment 349 - Campus d’Orsay, 15, avenue Jean Perrin, 91 405 Orsay Cedex, France
| | - Aurélien de la Lande
- Laboratoire de Chimie-Physique, CNRS UMR 8000, Université Paris Sud, Bâtiment 349 - Campus d’Orsay, 15, avenue Jean Perrin, 91 405 Orsay Cedex, France
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43
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Taguchi AT, O'Malley PJ, Wraight CA, Dikanov SA. Conformational differences between the methoxy groups of QA and QB site ubisemiquinones in bacterial reaction centers: a key role for methoxy group orientation in modulating ubiquinone redox potential. Biochemistry 2013; 52:4648-55. [PMID: 23745576 DOI: 10.1021/bi400489b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ubiquinone is an almost universal, membrane-associated redox mediator. Its ability to accept either one or two electrons allows it to function in critical roles in biological electron transport. The redox properties of ubiquinone in vivo are determined by its environment in the binding sites of proteins and by the dihedral angle of each methoxy group relative to the ring plane. This is an attribute unique to ubiquinone among natural quinones and could account for its widespread function with many different redox complexes. In this work, we use the photosynthetic reaction center as a model system for understanding the role of methoxy conformations in determining the redox potential of the ubiquinone/semiquinone couple. Despite the abundance of X-ray crystal structures for the reaction center, quinone site resolution has thus far been too low to provide a reliable measure of the methoxy dihedral angles of the primary and secondary quinones, QA and QB. We performed 2D ESEEM (HYSCORE) on isolated reaction centers with ubiquinones (13)C-labeled at the headgroup methyl and methoxy substituents, and have measured the (13)C isotropic and anisotropic components of the hyperfine tensors. Hyperfine couplings were compared to those derived by DFT calculations as a function of methoxy torsional angle allowing estimation of the methoxy dihedral angles for the semiquinones in the QA and QB sites. Based on this analysis, the orientation of the 2-methoxy groups are distinct in the two sites, with QB more out of plane by 20-25°. This corresponds to an ≈50 meV larger electron affinity for the QB quinone, indicating a substantial contribution to the experimental difference in redox potentials (60-75 mV) of the two quinones. The methods developed here can be readily extended to ubiquinone-binding sites in other protein complexes.
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Affiliation(s)
- Alexander T Taguchi
- Center for Biophysics and Computational Biology, §Department of Biochemistry, and ‡Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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Guo Z, Woodbury NW, Pan J, Lin S. Protein dielectric environment modulates the electron-transfer pathway in photosynthetic reaction centers. Biophys J 2013. [PMID: 23199926 DOI: 10.1016/j.bpj.2012.09.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The replacement of tyrosine by aspartic acid at position M210 in the photosynthetic reaction center of Rhodobacter sphaeroides results in the generation of a fast charge recombination pathway that is not observed in the wild-type. Apparently, the initially formed charge-separated state (cation of the special pair, P, and anion of the A-side bacteriopheophytin, H(A)) can decay rapidly via recombination through the neighboring bacteriochlorophyll (B(A)) soon after formation. The charge-separated state then relaxes over tens of picoseconds and recombination slows to the hundreds-of-picoseconds or nanosecond timescale. This dielectric relaxation results in a time-dependent blue shift of B(A)(-) absorption, which can be monitored using transient absorbance measurements. Protein dynamics also appear to modulate the electron transfer between H(A) and the next electron carrier, Q(A) (a ubiquinone). The kinetics of this reaction are complex in the mutant, requiring two kinetic terms, and the spectra associated with the two terms are distinct; a red shift of the H(A) ground-state bleaching is observed between the shorter and longer H(A)-to-Q(A) electron-transfer phases. The kinetics appears to be pH-independent, suggesting a negligible contribution of static heterogeneity originating from protonation/deprotonation in the ground state. A dynamic model based on the energy levels of the two early charge-separated states, P(+)B(A)(-) and P(+)H(A)(-), has been developed in which the energetics of these states is modulated by fast protein dielectric relaxations and this in turn alters both the kinetic complexity of the reaction and the reaction pathway.
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Affiliation(s)
- Zhi Guo
- The Biodesign Institute at Arizona State University, Tempe, Arizona, USA
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Sai Sankar Gupta KB, Alia A, Buda F, de Groot HJM, Matysik J. Bacteriopheophytin a in the active branch of the reaction center of rhodobacter sphaeroides is not disturbed by the protein matrix as shown by 13C photo-CIDNP MAS NMR. J Phys Chem B 2013; 117:3287-97. [PMID: 23452037 DOI: 10.1021/jp3121319] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic structure of bacteriopheophytin a (BPhe a), the primary electron acceptor (ΦA) in photosynthetic reaction centers (RCs) of the purple bacterium Rhodobacter sphaeroides, is investigated by photochemically induced dynamic nuclear polarization (photo-CIDNP) magic-angle spinning (MAS) NMR spectroscopy at atomic resolution. By using various isotope labeling systems, introduced by adding different (13)C selectively labeled δ-aminolevulinic acid precursors in the growing medium of R. sphaeroides wild type (WT), we were able to extract light-induced (13)C NMR signals originating from the primary electron acceptor. The assignments are backed by theoretical calculations. By comparison of these chemical shifts to those obtained from monomeric BPhe a in solution, it is demonstrated that ΦA in the active branch appears to be electronically close to free bacteriopheophytin. Hence, there is little effect of the protein surrounding on the cofactor functionally which contributes with its standard redox potential to the electron transfer process that is asymmetric.
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Gibasiewicz K, Pajzderska M, Dobek A, Brettel K, Jones MR. Analysis of the kinetics of P+ HA- recombination in membrane-embedded wild-type and mutant Rhodobacter sphaeroides reaction centers between 298 and 77 K indicates that the adjacent negatively charged QA ubiquinone modulates the free energy of P+ HA- and may influence the rate of the protein dielectric response. J Phys Chem B 2013; 117:11112-23. [PMID: 23477295 DOI: 10.1021/jp4011235] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Time-resolved spectroscopic studies of recombination of the P(+)HA(-) radical pair in photosynthetic reaction centers (RCs) from Rhodobacter sphaeroides give an opportunity to study protein dynamics triggered by light and occurring over the lifetime of P(+)HA(-). The state P(+)HA(-) is formed after the ultrafast light-induced electron transfer from the primary donor pair of bacteriochlorophylls (P) to the acceptor bacteriopheophytin (HA). In order to increase the lifetime of this state, and thus increase the temporal window for the examination of protein dynamics, it is possible to block forward electron transfer from HA(-) to the secondary electron acceptor QA. In this contribution, the dynamics of P(+)HA(-) recombination were compared at a range of temperatures from 77 K to room temperature, electron transfer from HA(-) to QA being blocked either by prereduction of QA or by genetic removal of QA. The observed P(+)HA(-) charge recombination was significantly slower in the QA-deficient RCs, and in both types of complexes, lowering the temperature from RT to 77 K led to a slowing of charge recombination. The effects are explained in the frame of a model in which charge recombination occurs via competing pathways, one of which is thermally activated and includes transient formation of a higher-energy state, P(+)BA(-). An internal electrostatic field supplied by the negative charge on QA increases the free energy levels of the state P(+)HA(-), thus decreasing its energetic distance to the state P(+)BA(-). In addition, the dielectric response of the protein environment to the appearance of the state P(+)HA(-) is accelerated from ∼50-100 ns in the QA-deficient mutant RCs to ∼1-16 ns in WT RCs with a negatively charged QA(-). In both cases, the temperature dependence of the protein dynamics is weak.
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Affiliation(s)
- Krzysztof Gibasiewicz
- Department of Physics, Adam Mickiewicz University , ul. Umultowska 85, 61-614 Poznań, Poland
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Verkhovsky M, Bloch DA, Verkhovskaya M. Tightly-bound ubiquinone in the Escherichia coli respiratory Complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1550-6. [DOI: 10.1016/j.bbabio.2012.04.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 04/23/2012] [Accepted: 04/25/2012] [Indexed: 12/12/2022]
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Li K, Wang M, Wang J, Zhu R, Sun D, Sun X, Wang SL. Photoionization of Oxidized Coenzyme Q in Microemulsion: Laser Flash Photolysis Study in Biomembrane-like System. Photochem Photobiol 2012; 89:61-7. [DOI: 10.1111/j.1751-1097.2012.01180.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Thamarath SS, Bode BE, Prakash S, Sai Sankar Gupta KB, Alia A, Jeschke G, Matysik J. Electron Spin Density Distribution in the Special Pair Triplet of Rhodobacter sphaeroides R26 Revealed by Magnetic Field Dependence of the Solid-State Photo-CIDNP Effect. J Am Chem Soc 2012; 134:5921-30. [DOI: 10.1021/ja2117377] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Bela E. Bode
- Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands
- EaStCHEM and Biomedical Sciences
Research Complex, University of St Andrews, St Andrews, KY16 9ST, Scotland
| | - Shipra Prakash
- Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands
| | | | - A. Alia
- Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands
| | - Gunnar Jeschke
- Institut für Physikalische
Chemie, Eidgenössische Technische Hochschule, Zürich, Switzerland
| | - Jörg Matysik
- Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands
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Leonova MM, Fufina TY, Vasilieva LG, Shuvalov VA. Structure-function investigations of bacterial photosynthetic reaction centers. BIOCHEMISTRY (MOSCOW) 2012; 76:1465-83. [DOI: 10.1134/s0006297911130074] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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