51
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Frank HA, Innes J, Aldema M, Neumann R, Schenck CC. Triplet state EPR of reaction centers from the His(L173)→Leu (L173) mutant of Rhodobacter sphaeroides which contains a heterodimer primary donor. PHOTOSYNTHESIS RESEARCH 1993; 38:99-109. [PMID: 24317835 DOI: 10.1007/bf00015066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/1993] [Accepted: 08/11/1993] [Indexed: 06/02/2023]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy has been used to examine the triplet states in reaction centers of Rhodobacter sphaeroides which have undergone a genetic modification affecting the primary donor. Reaction centers containing the His(L173)→Leu(L173) substitution in the amino acid sequence have a primary donor which consists of a BChl-BPh heterodimer. The triplets formed in this heterodimer reaction center were compared with those formed in the wild-type reaction center which contains the BChl-BChl homodimer. Both reaction centers transfer triplet energy to the carotenoid under illumination at liquid nitrogen temperatures (∼90 K). However, the intensity of the carotenoid triplet signal is significantly decreased in the Leu(L173) mutant compared with the wild-type reaction center. At 12 K, in wild-type reaction centers only the primary donor triplet is observed. The Leu(L173) mutant exhibits a signal similar to that observed by Bylina et al. (1990) in His(M200)→Leu(M200) mutant reaction centers from Rb. capsulatus. The values of the zero-field splitting parameters of this triplet are discussed within the context of various models for the primary donor triplet state. No alteration in the ability of the carotenoid to quench the primary donor triplet state results from mutations at these sites.
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Affiliation(s)
- H A Frank
- Department of Chemistry, University of Connecticut, 06269-3060, Storrs, CT, USA
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52
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Frank HA, Chynwat V, Hartwich G, Meyer M, Katheder I, Scheer H. Carotenoid triplet state formation in Rhodobacter sphaeroides R-26 reaction centers exchanged with modified bacteriochlorophyll pigments and reconstituted with spheroidene. PHOTOSYNTHESIS RESEARCH 1993; 37:193-203. [PMID: 24317800 DOI: 10.1007/bf00032823] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/1993] [Accepted: 06/03/1993] [Indexed: 06/02/2023]
Abstract
Triplet state electron paramagnetic resonance (EPR) experiments have been carried out at X-band on Rb. sphaeroides R-26 reaction centers that have been reconstituted with the carotenoid, spheroidene, and exchanged with 13(2)-OH-Zn-bacteriochlorophyll a and [3-vinyl]-13(2)-OH-bacteriochlorophyll a at the monomeric, 'accessory' bacteriochlorophyll sites BA,B or with pheophytin a at the bacteriopheophytin sites HA,B. The primary donor and carotenoid triplet state EPR signals in the temperature range 95-150 K are compared and contrasted with those from native Rb. sphaeroides wild type and Rb. sphaeroides R-26 reaction centers reconstituted with spheroidene. The temperature dependencies of the EPR signals are strikingly different for the various samples. The data prove that triplet energy transfer from the primary donor to the carotenoid is mediated by the monomeric, BChlB molecule. Furthermore, the data show that triplet energy transfer from the primary donor to the carotenoid is an activated process, the efficiency of which correlates with the estimated triplet state energies of the modified pigments.
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Affiliation(s)
- H A Frank
- Department of Chemistry, University of Connecticut, 215 Glenbrook Road, 06269-3060, Storrs, CT, USA
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53
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Abstract
The recent proliferation of data obtained from mutant forms of cytochrome oxidase and analogous enzymes has necessitated a re-examination of existing structural models. A new model is proposed, consistent with these data, which brings several protonatable residues (Y244, D298, D300, T309, T316, K319, T326) into the vicinity of the binuclear centre, suggestive of a proton-transferring function. In addition, we also consider those residues which may participate in electron transport between CuA and haem a. We suggest several potential lines of investigation.
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Affiliation(s)
- S Brown
- Glynn Research Institute, Bodmin, Cornwall, UK
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54
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The effect of pressure on charge separation in photosynthetic bacterial reaction centers of Rhodopseudomonas viridis. Chem Phys Lett 1992. [DOI: 10.1016/0009-2614(92)85061-e] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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55
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Zhang FG, Gillbro T, van Grondelle R, Sundström V. Dynamics of energy transfer and trapping in the light-harvesting antenna of Rhodopseudomonas viridis. Biophys J 1992; 61:694-703. [PMID: 1504241 PMCID: PMC1260287 DOI: 10.1016/s0006-3495(92)81874-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
By low intensity picosecond absorption spectroscopy it is shown that the exciton lifetime in the light-harvesting antenna of Rhodopseudomonas (Rps.) viridis membranes with photochemically active reaction centers at room temperature is 60 +/- 10 ps. This lifetime reflects the overall trapping rate of the excitation energy by the reaction center. With photochemically inactive reaction centers, in the presence of P+, the exciton lifetime increases to 150 +/- 15 ps. Prereducing the secondary electron acceptor QA does not prevent primary charge separation, but slows it down from 60 to 90 +/- 10 ps. Picosecond kinetics measured at 77 K with inactive reaction centers indicates that the light-harvesting antenna is spectrally homogeneous. Picosecond absorption anisotropy measurements show that energy transfer between identical Bchlb molecules occurs on the subpicosecond time scale. Using these experimental results as input to a random-walk model, results in strict requirements for the antenna-RC coupling. The model analysis prescribes fast trapping (approximately 1 ps) and an approximately 0.5 escape probability from the reaction center, which requires a more tightly coupled RC and antenna, as compared with the Bchla-containing bacteria Rhodospirillum (R.) rubrum and Rhodobacter (Rb.) sphaeroides.
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Affiliation(s)
- F G Zhang
- Department of Physical Chemistry, University of Umeå, Sweden
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56
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Abstract
Powerful first-order analysis of intraprotein electron transfer is developed from electron-transfer measurements both in biological and in chemical systems. A variation of 20 A in the distance between donors and acceptors in protein changes the electron-transfer rate by 10(12)-fold. Protein presents a uniform electronic barrier to electron tunnelling and a uniform nuclear characteristic frequency, properties similar to an organic glass. Selection of distance, free energy and reorganization energy are sufficient to define rate and directional specificity of biological electron transfer, meeting physiological requirements in diverse systems.
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Affiliation(s)
- C C Moser
- Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia 19104
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57
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Chapter 4 High-resolution crystal structures of bacterial photosynthetic reaction centers. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/s0167-7306(08)60172-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
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58
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Mathis P, Sinning I, Michel H. Kinetics of electron transfer from the primary to the secondary quinone in rhodopseudomonas viridis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1992. [DOI: 10.1016/s0005-2728(05)80330-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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59
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Dressler K, Umlauf E, Schmidt S, Hamm P, Zinth W, Buchanan S, Michel H. Detailed studies of the subpicosecond kinetics in the primary electron transfer of reaction centers of Rhodopseudomonas viridis. Chem Phys Lett 1991. [DOI: 10.1016/0009-2614(91)80062-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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60
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Baciou L, Gulik-Krzywicki T, Sebban P. Involvement of the protein-protein interactions in the thermodynamics of the electron-transfer process in the reaction centers from Rhodopseudomonas viridis. Biochemistry 1991; 30:1298-302. [PMID: 1991111 DOI: 10.1021/bi00219a020] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Reaction centers from Rhodopseudomonas viridis were reconstituted into dimyristoylphosphatidylcholine (DMPC) and dielaidoylphosphatidylcholine (DEPC) liposomes. Freeze-fracture electron micrographs were performed on the samples frozen from temperatures above and below the phase transition temperatures of those lipids (Tc = 23 and 9.5 degrees C, in DMPC and DEPC, respectively). Above Tc, in the fluid conformation of the lipids, the reaction centers are randomly distributed in the vesicle membranes. Below Tc, aggregation of the proteins occurs. The Arrhenius plots of the rate constants of the charge recombination between P+ and QA- display a break at about 24 degrees C in DMPC vesicles and about 10 degrees C in DEPC vesicles (P represents the primary electron donor, a dimer of bacteriochlorophyll, and QA the primary quinone electron acceptor). This is in contrast to what was previously observed for the proteoliposomes of egg yolk phosphatidylcholine and for chromatophores [Baciou, L., Rivas, E., & Sebban, P. (1990) Biochemistry 29, 2966-2976], for which Arrhenius plots were linear. In DMPC and DEPC proteoliposomes, the activation parameters were very different on the two sides of Tc (delta H degrees for T less than Tc = 2.5 times delta H degrees for T greater than Tc), leading however, to the same delta G degrees values. Taking into account the structural and thermodynamic data, we suggest that, in vivo, protein-protein interactions play a role in the thermodynamic parameters associated with the energy stabilization process within the reaction centers.
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Affiliation(s)
- L Baciou
- UPR 407, CNRS, Gif/Yvette, France
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61
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McDowell LM, Kirmaier C, Holten D. Charge transfer and charge resonance states of the primary electron donor in wild-type and mutant bacterial reaction centers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1990. [DOI: 10.1016/0005-2728(90)90153-u] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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62
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Holzapfel W, Finkele U, Kaiser W, Oesterhelt D, Scheer H, Stilz HU, Zinth W. Initial electron-transfer in the reaction center from Rhodobacter sphaeroides. Proc Natl Acad Sci U S A 1990; 87:5168-72. [PMID: 11607090 PMCID: PMC54283 DOI: 10.1073/pnas.87.13.5168] [Citation(s) in RCA: 152] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The initial electron transfer steps in the photosynthetic reaction center of the purple bacterium Rhodobacter sphaeroides have been investigated by femtosecond time-resolved spectroscopy. The experimental data taken at various wavelengths demonstrate the existence of at least four intermediate states within the first nanosecond. The difference spectra of the intermediates and transient photodichroism data are fully consistent with a sequential four-step model of the primary electron transfer: Light absorption by the special pair P leads to the state P*. From the excited primary donor P*, the electron is transferred within 3.5 +/- 0.4 ps to the accessory bacteriochlorophyll B. State P+B- decays with a time constant of 0.9 +/- 0.3 ps passing the electron to the bacteriopheophytin H. Finally, the electron is transferred from H- to the quinone QA within 220 +/- 40 ps.
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Affiliation(s)
- W Holzapfel
- Physik-Department der Technischen Universität München, Munich, Federal Republic of Germany
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63
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Baciou L, Rivas E, Sebban P. P+QA- and P+QB- charge recombinations in Rhodopseudomonas viridis chromatophores and in reaction centers reconstituted in phosphatidylcholine liposomes. Existence of two conformational states of the reaction centers and effects of pH and o-phenanthroline. Biochemistry 1990; 29:2966-76. [PMID: 2186805 DOI: 10.1021/bi00464a012] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The P+QA- and P+QB- charge recombination decay kinetics were studied in reaction centers from Rhodopseudomonas viridis reconstituted in phosphatidylcholine bilayer vesicles (proteoliposomes) and in chromatophores. P represents the primary electron donor, a dimer of bacteriochlorophyll; QA and QB are the primary and secondary stable quinone electron acceptors, respectively. In agreement with recent findings for reaction centers isolated in detergent [Sebban, P., & Wraight, C.A. (1989) Biochim. Biophys. Acta 974, 54-65] the P+QA- decay kinetics were biphasic (kfast and kslow). Arrhenius plots of the kinetics were linear, in agreement with the hypothesis of a thermally activated process (probably via P+I-; I is the first electron acceptor, a bacteriopheophytin) for the P+QA- charge recombination. Similar activation free energies (delta G) for this process were found in chromatophores and in proteoliposomes. Significant pH dependences of kfast and kslow were observed in chromtophores and in proteoliposomes. In the pH range 5.5-11, the pH titration curves of kfast and kslow were interpreted in terms of the existence of three protonable groups, situated between I- and QA-, which modulate the free energy difference between P+I- and P+QA-. In proteoliposomes, a marked effect of o-phenanthroline was observed on two of the three pKs, shifting one of them by more than 2 pH units. On the basis of recent structural data, we suggest a possible interpretation for this effect, which is much smaller in Rhodobacter sphaeroides. The decay kinetics of P+QB- were also biphasic. Marked pH dependences of the rate constants and of the relative proportions of both phases were also detected for these decays. The major conclusion of this work comes from the biphasicity of the P+QB- decay kinetics. We had suggested previously that biphasicity of the P+QA- charge recombination in Rps. viridis comes from nonequilibrium between protonation states of the reaction centers due to comparable rates of the protonation events and charge recombination. This hypothesis does not hold since the P+QB- decays occur on a time scale (tau approximately 300 ms at pH 8) much longer than protonation events. This leads to the conclusion that kfast and kslow (for both P+QA- and P+QB-) are related to conformational states of the reaction centers, existing before the flash. In addition, the fast and slow decays of P+QB- are related to those measured for P+QA-, via the calculations of the QA-QB in equilibrium QAQB- apparent equilibrium constants, K2.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- L Baciou
- Laboratoire de Photosynthèse, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
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64
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Competition between energy trapping and exciton annihilation in the lake model of the photosynthetic membrane of purple bacteria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1990. [DOI: 10.1016/0005-2728(90)90034-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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65
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Trissl HW, Breton J, Deprez J, Dobek A, Leibl W. Trapping kinetics, annihilation, and quantum yield in the photosynthetic purple bacterium Rps. viridis as revealed by electric measurement of the primary charge separation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1990. [DOI: 10.1016/0005-2728(90)90037-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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66
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Huber R. E. Antonini Plenary lecture. A structural basis of light energy and electron transfer in biology. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 187:283-305. [PMID: 2404762 DOI: 10.1111/j.1432-1033.1990.tb15305.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Aspects of intramolecular light energy and electron transfer will be discussed for three protein cofactor complexes, whose three-dimensional structures have been elucidated by X-ray crystallography: components of light-harvesting cyanobacterial phycobilisomes, the purple bacterial reaction centre and the blue multi-copper oxidases. A wealth of functional data is available for these systems which allow specific correlations between structure and function, and general conclusions about light energy and electron transfer in biological materials to be made.
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Affiliation(s)
- R Huber
- Max-Planck-Institut für Biochemie, Martinsried, Federal Republic of Germany
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67
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A Structural Basis for Electron Transfer in Bacterial Photosynthesis. ACTA ACUST UNITED AC 1990. [DOI: 10.1007/978-94-009-0489-7_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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68
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Freeman JC, Blankenship RE. Isolation and characterization of the membrane-bound cytochrome c-554 from the thermophilic green photosynthetic bacterium Chloroflexus aurantiacus. PHOTOSYNTHESIS RESEARCH 1990; 23:29-38. [PMID: 24420989 DOI: 10.1007/bf00030060] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/1988] [Accepted: 11/21/1988] [Indexed: 06/03/2023]
Abstract
The membrane-bound photooxidizable cytochrome c-554 from Chloroflexus aurantiacus has been purified. The purified protein runs as a single heme staining band on SDS-PAGE with an apparent molecular mass of 43 000 daltons. An extinction coefficient of 28 ± 1 mM(-1) cm(-1) per heme at 554 nm was found for the dithionite-reduced protein. The potentiometric titration of the hemes takes place over an extended range, showing clearly that the protein does not contain a single heme in a well-defined site. The titration can be fit to a Nernst curve with midpoint potentials at 0, +120, +220 and +300 mV vs the standard hydrogen electrode. Pyridine hemochrome analysis combined with a Lowry protein assay and the SDS-PAGE molecular weight indicates that there are a minimum of three, and probably four hemes per peptide. Amino acid analysis shows 5 histidine residues and 29% hydrophobic residues in the protein. This cytochrome appears to be functionally similar to the bound cytochrome from Rhodopseudomonas viridis. Both cytochrome c-554 from C. aurantiacus and the four-heme cytochrome c-558-553 from R. viridis appear to act as direct electron donors to the special bacteriochlorophyll pair of the photosynthetic reaction center. They have a similar content of hydrophobic amino acids, but differ in isoelectric point, thermodynamic characteristics, spectral properties, and in their ability to be photooxidized at low temperature.
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Affiliation(s)
- J C Freeman
- Department of Chemistry, Arizona State University, 85287-1604, Tempe, AZ, USA
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69
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Huber R. Nobel lecture. A structural basis of light energy and electron transfer in biology. Biosci Rep 1989; 9:635-73. [PMID: 2692721 DOI: 10.1007/bf01114805] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Aspects of intramolecular light energy and electron transfer will be discussed for three protein cofactor complexes, whose three-dimensional structures have been elucidated by x-ray crystallography: Components of light harvesting cyanobacterial phycobilisomes, the purple bacterial reaction centre, and the blue multi-copper oxidases. A wealth of functional data is available for these systems which allow specific correlations between structure and function and general conclusions about light energy and electron transfer in biological materials to be made.
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Affiliation(s)
- R Huber
- Max-Planck-Institut für Biochemie, Martinsried
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70
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Friesner RA, Won YD. Spectroscopy and electron transfer dynamics of the bacterial photosynthetic reaction center. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 977:99-122. [PMID: 2679885 DOI: 10.1016/s0005-2728(89)80062-3] [Citation(s) in RCA: 103] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- R A Friesner
- Department of Chemistry University of Texas, Austin 78712
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71
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Frank HA, Violette CA. Monomeric bacteriochlorophyll is required for the triplet energy transfer between the primary donor and the carotenoid in photosynthetic bacterial reaction centers. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 976:222-32. [PMID: 2551387 DOI: 10.1016/s0005-2728(89)80234-8] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Reaction centers from the carotenoidless mutant Rb. sphaeroides R26 were treated with sodium borohydride which is known to remove one of the accessory monomeric bacteriochlorophylls (BB). Subsequently, the carotenoid, spheroidene, was incorporated into the modified reaction centers. It is demonstrated by optical absorption and circular dichroism experiments that spheroidene, reconstituted into the sodium borohydride-treated Rb. sphaeroides R26 reaction centers, is bound in a single site, in the same environment and with the same structure as spheroidene reconstituted into untreated (native) Rb. sphaeroides R26 reaction centers. Transient optical and electron spin resonance spectroscopic data indicate that unless the accessory BB is present, the primary donor-to-carotenoid triplet energy transfer reaction is inhibited. These observations provide direct evidence for the involvement of the accessory BB in the triplet energy transfer pathway.
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Affiliation(s)
- H A Frank
- Department of Chemistry, University of Connecticut, Storrs 06269
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72
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Abstract
The Cu(II) sites of azurins, the blue single copper proteins, isolated from Pseudomonas aeruginosa and Alcaligenes spp. (Iwasaki) are reduced by CO2- radicals, produced by pulse radiolysis, in two distinct reaction steps: (i) a fast bimolecular phase, at the rates (5.0 +/- 0.8) x 10(8) M-1.s-1 (P. aeruginosa) and (6.0 +/- 1.0) x 10(8) M-1.s-1 (Alcaligenes); (ii) a slow unimolecular phase with specific rates of 44 +/- 7 s-1 in the former and 8.5 +/- 1.5 s-1 for the latter (all at 298 K, 0.1 M ionic strength). Concomitant with the fast reduction of Cu(II), the single disulfide bridge linking cysteine-3 to -26 in these proteins is reduced to the RSSR- radical ion as evidenced by its characteristic absorption band centered at 410 nm. This radical ion decays in a unimolecular process with a rate identical to that of the slow Cu(II) reduction phase in the respective protein, thus clearly suggesting that a long-range intramolecular electron transfer occurs between the RSSR- radicals and the Cu(II) site. The temperature dependence of the internal electron transfer process in both proteins was measured over the 4 degrees C to 42 degrees C range. The activation parameters derived are delta H* = 47.5 +/- 4.0 and 16.7 +/- 1.5 kJ.mol-1; and delta S not equal to = -56.5 +/- 7.0 and -171 +/- 18 J.K-1.mol-1, respectively. Using the Marcus theory, we found that the intramolecular electron transfer rates and their activation parameters observed for the two azurins correlate well with the distances between the reactive sites, their redox potential, and the nature of the separating medium. Thus, azurins with distinct structural and reactivity characteristics isolated from different bacteria or modified by site-directed mutagenesis can be used in comparing long-range electron transfer process between their conserved disulfide bridge and the Cu(II) sites.
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Affiliation(s)
- O Farver
- Department of Chemistry, Royal Danish School of Pharmacy, Copenhagen
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73
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Holzapfel W, Finkele U, Kaiser W, Oesterhelt D, Scheer H, Stilz H, Zinth W. Observation of a bacteriochlorophyll anion radical during the primary charge separation in a reaction center. Chem Phys Lett 1989. [DOI: 10.1016/0009-2614(89)87543-8] [Citation(s) in RCA: 228] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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74
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Huber R. Eine strukturelle Grundlage für die Übertragung von Lichtenergie und Elektronen in der Biologie (Nobel-Vortrag). Angew Chem Int Ed Engl 1989. [DOI: 10.1002/ange.19891010704] [Citation(s) in RCA: 123] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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75
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Lous E, Hoff A. Isotropic and linear dichroic triplet-minus-singlet absorbance difference spectra of two carotenoid-containing bacterial photosynthetic reaction centers in the temperature range 10–288 K. An analysis of bacteriochlorophyll-carotenoid triplet transfer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1989. [DOI: 10.1016/s0005-2728(89)80169-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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76
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Heterogeneity of the P+Q−A recombination kinetics in reaction centers from Rhodopseudomonas viridis: the effects of pH and temperature. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1989. [DOI: 10.1016/s0005-2728(89)80165-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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77
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Tang D, Jankowiak R, Small GJ, Tiede DM. Structured hole burned spectra of the primary donor state absorption region of Rhodopseudomonas viridis. Chem Phys 1989. [DOI: 10.1016/0301-0104(89)87083-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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78
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Electron-spin polarization in the donor triplet state of bacterial photosynthetic reaction centers. I. Microsecond time-resolved EPR of Rhodopseudomonas viridis reaction centers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1988. [DOI: 10.1016/0005-2728(88)90241-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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79
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Electron spin polarization in the donor triplet state of bacterial photosynthetic reaction centres. II. Anisotropic inversion of electron spin polarization in a three-spin model reaction centre. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1988. [DOI: 10.1016/0005-2728(88)90242-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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80
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Dracheva SM, Drachev LA, Konstantinov AA, Semenov AYu, Skulachev VP, Arutjunjan AM, Shuvalov VA, Zaberezhnaya SM. Electrogenic steps in the redox reactions catalyzed by photosynthetic reaction-centre complex from Rhodopseudomonas viridis. EUROPEAN JOURNAL OF BIOCHEMISTRY 1988; 171:253-64. [PMID: 2828052 DOI: 10.1111/j.1432-1033.1988.tb13784.x] [Citation(s) in RCA: 123] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Electrogenic and redox events in the reaction-centre complexes from Rhodopseudomonas viridis have been studied. In contrast to the previous points of view it is shown that all the four hemes of the tightly bound cytochrome c have different Em values (-60, +20, +310 and +380 mV). The first three hemes reveal alpha absorption maxima at 554 nm, 552 nm and 556 nm respectively. The 380-mV heme displays a split alpha band with a maximum at 559 nm and a shoulder at 552 nm. Such a splitting is due to non-degenerated Qx and Qy transitions in the iron-porphyrin ring as demonstrated by magnetic circular dichroism spectra. Fast kinetic measurements show that, at redox potentials when only high-potential hemes c-559 and c-556 are reduced, heme c-559 appears to be the electron donor to P-960+ (tau = 0.32 microsecond) whereas heme c-556 serves to rereduce c-559 (tau = 2.5 microsecond). Upon reduction of the third heme (c-552), the P-960+ reduction rate increases twofold (tau = 0.17 microsecond) and all photoinduced redox events within the cytochrome appear to be complete in less than 1 microsecond after the flash. The following sequence of the redox centers is tentatively suggested: c-554, c-556, c-552, c-559, P-960. To study electrogenesis, the reaction-centre complexes from Rps. viridis were incorporated into asolectin liposomes, and fast kinetics of laser flash-induced electric potential difference has been measured in proteoliposomes adsorbed on a phospholipid-impregnated film. The electrical difference induced by a single 15-ns flash was found to be as high as 100 mV. The photoelectric response has been found to involve four electrogenic stages associated with (I) QA reduction by P-960; (II) reduction of P-960+ by heme c-559; (III) reduction of c-559 by c-556 and (IV) protonation of Q2-B. The relative contributions of stages I, II, III and IV are found to be equal to 70%, 15%, 5% and 10%, respectively, of the overall electrogenic process. At the same time, the first three respective distances along the axis normal to the membrane plane covered by electrons, calculated from X-ray data of Deisenhofer et al. [J. Mol. Biol. 180, 385-398 (1984)], are 22%, 18.5% and 26%. This indicates that the efficiency of electrogenic phases depends first of all upon the value of the dielectric constant of the respective membrane regions rather than upon the distance between the redox groups involved.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- S M Dracheva
- A. N. Belozersky Laboratory of Molecular Biology and Bioorganic Chemistry, Moscow State University, USSR
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81
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Shopes RJ, Wraight CA. Charge recombination from the P+QA- state in reaction centers from Rhodopseudomonas viridis. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 893:409-25. [PMID: 3651444 DOI: 10.1016/0005-2728(87)90093-4] [Citation(s) in RCA: 72] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The rate of decay of the flash-oxidized primary electron donor, P+, from the state P+QA- was studied in reaction centers from Rhodopseudomonas viridis, containing only the primary menaquinone electron acceptor (QA). At 295 K, in 100 mM NaCl and in the presence of o-phenanthroline, the rate of recombination was 470 +/- 15 s-1 at pH 7 and 570 +/- 20 s-1 at pH 9. The rate at ambient temperatures varied somewhat with viscosity, pH and ionic strength. Between 310 K and 275 K, the temperature dependences of the rate, at pH 7 and pH 9, were linear in an Arrhenius plot, with apparent activation energies of 0.20 eV and 0.16 eV, respectively. At lower temperatures, however, the dependences deviated from this behavior. In 60% glycerol (pH 7) the recombination rate was 370 +/- 10 s-1 at 295 K. As the temperature was lowered, the rate decreased but leveled off to a value of 105 +/- 5 s-1 at 170 K and was independent of temperature from 170 K to 100 K. In 60% ethylene glycol, the temperature dependence was similar, but the rate fell to a minimum of 75 s-1 at 170 K and then increased slightly at lower temperatures; it finally became temperature independent, with a value of about 100 s-1, at 110 K. The overall temperature dependence is consistent with charge recombination by two competing pathways: a direct electron-tunneling process which dominates at low temperature (less than 250 K), and a thermally activated process via a higher energy state, M, which decays rapidly to the ground state. The indirect route dominates at high temperature (above 250 K). Taking into account the contribution from the low-temperature pathway, the activation energy (enthalpy) for the activated process, in aqueous buffer, was determined to be 0.25 eV (at pH 7) and 0.19 eV (at pH 9). A likely candidate for M is P+I- (PF), where I is the intermediate bacteriopheophytin electron acceptor, and energetic arguments are presented in favor of this assignment. If a rate of decay of P+I- to the ground state, derived from the experimental value, was used in the description of the thermally activated P+QA- recombination process, the free-energy gap separating M and P+QA- could be estimated to be 0.27-0.28 eV, placing it about 0.95 eV above the ground state and 0.30 eV below the excited singlet state, P*.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- R J Shopes
- Department of Physiology and Biophysics, University of Illinois, Urbana 61801
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82
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Kirmaier C, Holten D. Primary photochemistry of reaction centers from the photosynthetic purple bacteria. PHOTOSYNTHESIS RESEARCH 1987; 13:225-260. [PMID: 24435821 DOI: 10.1007/bf00029401] [Citation(s) in RCA: 264] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/1987] [Accepted: 04/20/1987] [Indexed: 06/03/2023]
Abstract
Photosynthetic organisms transform the energy of sunlight into chemical potential in a specialized membrane-bound pigment-protein complex called the reaction center. Following light activation, the reaction center produces a charge-separated state consisting of an oxidized electron donor molecule and a reduced electron acceptor molecule. This primary photochemical process, which occurs via a series of rapid electron transfer steps, is complete within a nanosecond of photon absorption. Recent structural data on reaction centers of photosynthetic bacteria, combined with results from a large variety of photochemical measurements have expanded our understanding of how efficient charge separation occurs in the reaction center, and have changed many of the outstanding questions.
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Affiliation(s)
- C Kirmaier
- Department of Chemistry, Washington University, 63130, St. Louis, MO, USA
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83
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Takahashi Y, Hansson Ö, Mathis P, Satoh K. Primary radical pair in the Photosystem II reaction centre. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1987. [DOI: 10.1016/0005-2728(87)90147-2] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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84
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Källebring B, Larsson S. Singlet spectra of chromophores in the reaction center of rhodopseudomonas viridis as calculated by the CNDO/S method. Chem Phys Lett 1987. [DOI: 10.1016/0009-2614(87)80345-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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85
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Hoganson CW, Windsor MW, Farkas DI, Parson WW. Pressure effects on the photochemistry of bacterial photosynthetic reaction centers from Rhodobacter sphaeroides R-26 and Rhodopseudomonas viridis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1987. [DOI: 10.1016/0005-2728(87)90231-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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86
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Fischer SF, Scherer P. On the early charge separation and recombination processes in bacterial reaction centers. Chem Phys 1987. [DOI: 10.1016/0301-0104(87)80029-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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87
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Gillie J, Fearey B, Hayes J, Small G, Golbeck J. Persistent hole burning of the primary donor state of photosystem i: strong linear electron-phonon coupling. Chem Phys Lett 1987. [DOI: 10.1016/0009-2614(87)87144-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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88
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Shopes RJ, Levine LM, Holten D, Wraight CA. Kinetics of oxidation of the bound cytochromes in reaction centers from Rhodopseudomonas viridis. PHOTOSYNTHESIS RESEARCH 1987; 12:165-180. [PMID: 24435639 DOI: 10.1007/bf00047946] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/1986] [Revised: 02/11/1987] [Accepted: 02/11/1987] [Indexed: 06/03/2023]
Abstract
The initial oxidized species in the photochemical charge separation in reaction centers from Rps. viridis is the primary donor, P(+), a bacteriochlorophyll dimer. Bound c-type cytochromes, two high potential (Cyt c 558) and two low potential (Cyt c 553), act as secondary electron donors to P(+). Flash induced absorption changes were measured at moderate redox potential, when the high potential cytochromes were chemically reduced. A fast absorption change was due to the initial oxidation of one of the Cyt c 558 by P(+) with a rate of 3.7×10(6)s(-1) (τ=270nsec). A slower absorption change was attributable to a transfer, or sharing, of the remaining electron from one high potential heme to the other, with a rate of 2.8×10(5)s(-1) (τ=3.5 μsec). The slow change was measured at a number of wavelengths throughout the visible and near infrared and revealed that the two high potential cytochromes have slightly different differential absorption spectra, with α-band maxima at 559 nm (Cyt c 559) and 556.5 nm (Cyt c 556), and dissimilar electrochromic effects on nearby pigments. The sequence of electron transfers, following a flash, is: Cyt c 556→Cyt c 559→P(+). At lower redox potentials, a low midpoint potential cytochrome, Cyt c 553, is preferentially oxidized by P(+) with a rate of 7×10(6)s(-1) (τ=140 nsec). The assignment of the low and high potential cytochromes to the four, linearly arranged hemes of the reaction center is discussed. It is concluded that the closest heme to P must be the high potential Cyt c 559, and it is suggested that a likely arrangement for the four hemes is: c 553 c 556 c 553 c 559P.
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Affiliation(s)
- R J Shopes
- Department of Physiology and Biophysics, University of Illinois, 61801, Urbana, IL, USA
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90
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Popovic Z, Kovacs G, Vincett P, Alegria G, Dutton P. Electric field dependence of recombination kinetics in reaction centers of photosynthetic bacteria. Chem Phys 1986. [DOI: 10.1016/0301-0104(86)87079-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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91
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Kuhn H. Electron transfer mechanism in the reaction center of photosynthetic bacteria. PHYSICAL REVIEW. A, GENERAL PHYSICS 1986; 34:3409-3425. [PMID: 9897660 DOI: 10.1103/physreva.34.3409] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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92
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Shuvalov V, Amesz J, Duysens L. Picosecond charge separation upon selective excitation of the primary electron donor in reaction centers of Rhodopseudomonas viridis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1986. [DOI: 10.1016/0005-2728(86)90140-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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93
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Woodbury NW, Parson WW, Gunner MR, Prince RC, Dutton PL. Radical-pair energetics and decay mechanisms in reaction centers containing anthraquinones, naphthoquinones or benzoquinones in place of ubiquinone. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 851:6-22. [PMID: 3524681 DOI: 10.1016/0005-2728(86)90243-4] [Citation(s) in RCA: 185] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In reaction centers from Rhodobacter sphaeroides (formerly called Rhodopseudomonas sphaeroides), light causes an electron-transfer reaction that forms the radical pair state (P+I-, or PF) from the initial excited singlet state (P) of a bacteriochlorophyll dimer (P). Subsequent electron transfer to a quinone (Q) produces the state P+Q-. Back electron transfer can regenerate P from P+Q-, giving rise to 'delayed' fluorescence that decays with approximately the same lifetime as P+Q-. The free-energy difference between P+Q- and P can be determined from the initial amplitude of the delayed fluorescence. In the present work, we extracted the native quinone (ubiquinone) from Rps. sphaeroides reaction centers, and replaced it by various anthraquinones, naphthoquinones, and benzoquinones. We found a rough correlation between the halfwave reduction potential (E1/2) of the quinone used for reconstitution (as measured polarographically in dimethylformamide) and the apparent free energy of the state P+Q- relatively to P. As the E1/2 of the quinone becomes more negative, the standard free-energy gap between P+Q- and P decreases. However, the correlation is quantitatively weak. Apparently, the effective midpoint potentials (Em) of the quinones in situ depend subtly on interactions with the protein environment in the reaction center. Using the value of the Em for ubiquinone determined in native reaction centers as a reference, and the standard free energies determined for P+Q- in reaction centers reconstituted with other quinones, the effective Em values of 12 different quinones in situ are estimated. In native reaction centers, or in reaction centers reconstituted with quinones that give a standard free-energy gap of more than about 0.8 eV between P+Q- and P*, charge recombination from P+Q- to the ground state (PQ) occurs almost exclusively by a temperature-insensitive mechanism, presumably electron tunneling. When reaction centers are reconstituted with quinones that give a free-energy gap between P+Q- and P* of less than 0.8 with quinones that give a free-energy gap between P+Q- and P* of less than 0.8 eV, part or all of the decay proceeds through a thermally accessible intermediate. There is a linear relationship between the log of the rate constant for the decay of P+Q- via the intermediate state and the standard free energy of P+Q-. The higher the free energy, the faster the decay. The kinetic and thermodynamic properties of the intermediate appear not to depend strongly on the quinone used for reconstitution, indicating that the intermediate is probably not simply an activated form of P+Q-.(ABSTRACT TRUNCATED AT 400 WORDS)
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94
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Electric-field dependence of the quantum yield in reaction centers of photosynthetic bacteria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1986. [DOI: 10.1016/0005-2728(86)90246-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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95
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Kirmaier C, Blankenship RE, Holten D. Formation and decay of radical-pair state P+I− in Chloroflexus aurantiacus reaction centers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1986. [DOI: 10.1016/0005-2728(86)90182-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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96
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97
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98
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Nabedryk E, Mäntele W, Tavitian BA, Breton J. LIGHT-INDUCED FOURIER TRANSFORM INFRARED SPECTROSCOPIC INVESTIGATIONS OF THE INTERMEDIARY ELECTRON ACCEPTOR REDUTION IN BACTERIAL PHOTOSYNTHESIS. Photochem Photobiol 1986. [DOI: 10.1111/j.1751-1097.1986.tb05630.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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99
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Structure of the protein subunits in the photosynthetic reaction centre of Rhodopseudomonas viridis at 3Å resolution. Nature 1985; 318:618-24. [PMID: 22439175 DOI: 10.1038/318618a0] [Citation(s) in RCA: 1935] [Impact Index Per Article: 49.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The molecular structure of the photosynthetic reaction centre from Rhodopseudomonas viridis has been elucidated using X-ray crystallographic analysis. The central part of the complex consists of two subunits, L and M, each of which forms five membrane-spanning helices. We present the first description of the high-resolution structure of an integral membrane protein.
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100
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Breton J. Orientation of the chromophores in the reaction center of Rhodopseudomonas viridis. Comparison of low-temperature linear dichroism spectra with a model derived from X-ray crystallography. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1985. [DOI: 10.1016/0005-2728(85)90138-0] [Citation(s) in RCA: 125] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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