1
|
Kondo T, Itoh S, Matsuoka M, Azai C, Oh-oka H. Menaquinone as the Secondary Electron Acceptor in the Type I Homodimeric Photosynthetic Reaction Center of Heliobacterium modesticaldum. J Phys Chem B 2015; 119:8480-9. [PMID: 26075484 DOI: 10.1021/acs.jpcb.5b03723] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The type I photosynthetic reaction center (RC) of heliobacteria (hRC) is a homodimer containing cofactors almost analogous to those in the plant photosystem I (PS I). However, its three-dimensional structure is not yet clear. PS I uses phylloquinone (PhyQ) as a secondary electron acceptor (A1), while the available evidence has suggested that menaquinone (MQ) in hRC has no function as A1. The present study identified a new transient electron spin-polarized electron paramagnetic resonance (ESP-EPR) signal, arising from the radical pair of the oxidized electron donor and the reduced electron acceptor (P800(+)MQ(-)), in the hRC core complex and membranes from Heliobacterium modesticaldum. The ESP signal could be detected at 5-20 K upon flash excitation only after prereduction of the iron-sulfur center, F(X), and was selectively lost by extraction of MQ with diethyl ether. MQ was suggested to be located closer to F(X) than PhyQ in PS I based on the simulation of the unique A/E (A, absorption; E, emission) ESP pattern, the reduction/oxidation rates of MQ, and the power saturation property of the static MQ(-) signal. The result revealed the quinone usage as the secondary electron acceptor in hRC, as in the case of PS I.
Collapse
Affiliation(s)
| | | | - Masahiro Matsuoka
- §Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Chihiro Azai
- §Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Hirozo Oh-oka
- §Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| |
Collapse
|
2
|
Hingorani K, Pace R, Whitney S, Murray JW, Smith P, Cheah MH, Wydrzynski T, Hillier W. Photo-oxidation of tyrosine in a bio-engineered bacterioferritin 'reaction centre'-a protein model for artificial photosynthesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1821-34. [PMID: 25107631 DOI: 10.1016/j.bbabio.2014.07.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 07/11/2014] [Accepted: 07/29/2014] [Indexed: 11/18/2022]
Abstract
The photosynthetic reaction centre (RC) is central to the conversion of solar energy into chemical energy and is a model for bio-mimetic engineering approaches to this end. We describe bio-engineering of a Photosystem II (PSII) RC inspired peptide model, building on our earlier studies. A non-photosynthetic haem containing bacterioferritin (BFR) from Escherichia coli that expresses as a homodimer was used as a protein scaffold, incorporating redox-active cofactors mimicking those of PSII. Desirable properties include: a di-nuclear metal binding site which provides ligands for bivalent metals, a hydrophobic pocket at the dimer interface which can bind a photosensitive porphyrin and presence of tyrosine residues proximal to the bound cofactors, which can be utilised as efficient electron-tunnelling intermediates. Light-induced electron transfer from proximal tyrosine residues to the photo-oxidised ZnCe6(•+), in the modified BFR reconstituted with both ZnCe6 and Mn(II), is presented. Three site-specific tyrosine variants (Y25F, Y58F and Y45F) were made to localise the redox-active tyrosine in the engineered system. The results indicate that: presence of bound Mn(II) is necessary to observe tyrosine oxidation in all BFR variants; Y45 the most important tyrosine as an immediate electron donor to the oxidised ZnCe6(•+) and that Y25 and Y58 are both redox-active in this system, but appear to function interchangebaly. High-resolution (2.1Å) crystal structures of the tyrosine variants show that there are no mutation-induced effects on the overall 3-D structure of the protein. Small effects are observed in the Y45F variant. Here, the BFR-RC represents a protein model for artificial photosynthesis.
Collapse
Affiliation(s)
- Kastoori Hingorani
- Building 134, Linnaeus Way, Research School of Biology, The Australian National University, ACT 0200, Australia.
| | - Ron Pace
- Building 137, Sullivans Creek Road, Research School of Chemistry, The Australian National University, ACT 0200, Australia.
| | - Spencer Whitney
- Building 134, Linnaeus Way, Research School of Biology, The Australian National University, ACT 0200, Australia
| | - James W Murray
- 724 Sir Ernst Chain Building, South Kensington Campus, Division of Molecular Biosciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Paul Smith
- Building 137, Sullivans Creek Road, Research School of Chemistry, The Australian National University, ACT 0200, Australia
| | - Mun Hon Cheah
- Building 134, Linnaeus Way, Research School of Biology, The Australian National University, ACT 0200, Australia
| | - Tom Wydrzynski
- Building 134, Linnaeus Way, Research School of Biology, The Australian National University, ACT 0200, Australia
| | - Warwick Hillier
- Building 134, Linnaeus Way, Research School of Biology, The Australian National University, ACT 0200, Australia
| |
Collapse
|
3
|
Kawamori A, Katsuta N, Mino H, Ishii A, Minagawa J, Ono TA. Positions of Q(A)and Chl(Z)Relative to Tyrosine Y(Z)and Y(D)in Photosystem II Studied by Pulsed EPR. J Biol Phys 2013; 28:413-26. [PMID: 23345785 DOI: 10.1023/a:1020312621949] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PELDOR (Pulsed Electron eLectron DOuble Resonance) was applied to determinethe distance of between Y(Z)and Q(A) (-)inY(D)-less mutant of Chlamydomonas reinhardtiiin Tris-treatedand Zn-substituted preparation of photosystem II. The value of distance wasfound to be 34.5 ± 1 Â. A '2+1' electron spin echo method has beenapplied to measure the orientation of the radius-vector RfomY(D)to Chl(Z)in a membrane-oriented photosystem II. The anglebetween Rand the membrane normal nwas determined to be 50 ±5(°), using the distance 29.4 ± 0.5 Â determined in non-orientedPS II.
Collapse
Affiliation(s)
- A Kawamori
- Faculty of Science, Kwansei Gakuin University, Gakuen 2-1, Sanda, 669-1337 Japan
| | | | | | | | | | | |
Collapse
|
4
|
Shinopoulos KE, Brudvig GW. Cytochrome b₅₅₉ and cyclic electron transfer within photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1817:66-75. [PMID: 21864501 DOI: 10.1016/j.bbabio.2011.08.002] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 08/06/2011] [Accepted: 08/08/2011] [Indexed: 11/18/2022]
Abstract
Cytochrome b₅₅₉ (Cyt b₅₅₉), β-carotene (Car), and chlorophyll (Chl) cofactors participate in the secondary electron-transfer pathways in photosystem II (PSII), which are believed to protect PSII from photodamage under conditions in which the primary electron-donation pathway leading to water oxidation is inhibited. Among these cofactors, Cyt b₅₅₉ is preferentially photooxidized under conditions in which the primary electron-donation pathway is blocked. When Cyt b₅₅₉ is preoxidized, the photooxidation of several of the 11 Car and 35 Chl molecules present per PSII is observed. In this review, the discovery of the secondary electron donors, their structures and electron-transfer properties, and progress in the characterization of the secondary electron-transfer pathways are discussed. This article is part of a Special Issue entitled: Photosystem II.
Collapse
|
5
|
Deligiannakis Y. Electron paramagnetic relaxation enhancement produced onT1by anisotropic g-tensors in rigid systems. Mol Phys 2010. [DOI: 10.1080/00268970701624661] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
6
|
Tracewell CA, Brudvig GW. Multiple redox-active chlorophylls in the secondary electron-transfer pathways of oxygen-evolving photosystem II. Biochemistry 2008; 47:11559-72. [PMID: 18850718 PMCID: PMC2674297 DOI: 10.1021/bi801461d] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Photosystem II (PS II) is unique among photosynthetic reaction centers in having secondary electron donors that compete with the primary electron donors for reduction of P680(+). We have characterized the photooxidation and dark decay of the redox-active accessory chlorophylls (Chl) and beta-carotenes (Car) in oxygen-evolving PS II core complexes by near-IR absorbance and EPR spectroscopies at cryogenic temperatures. In contrast to previous results for Mn-depleted PS II, multiple near-IR absorption bands are resolved in the light-minus-dark difference spectra of oxygen-evolving PS II core complexes including two fast-decaying bands at 793 and 814 nm and three slow-decaying bands at 810, 825, and 840 nm. We assign these bands to chlorophyll cation radicals (Chl(+)). The fast-decaying bands observed after illumination at 20 K could be generated again by reilluminating the sample. Quantization by EPR gives a yield of 0.85 radicals per PS II, and the yield of oxidized cytochrome b 559 by optical difference spectroscopy is 0.15 per PS II. Potential locations of Chl(+) and Car(+) species, and the pathways of secondary electron transfer based on the rates of their formation and decay, are discussed. This is the first evidence that Chls in the light-harvesting proteins CP43 and CP47 are oxidized by P680(+) and may have a role in Chl fluorescence quenching. We also suggest that a possible role for negatively charged lipids (phosphatidyldiacylglycerol and sulfoquinovosyldiacylglycerol identified in the PS II structure) could be to decrease the redox potential of specific Chl and Car cofactors. These results provide new insight into the alternate electron-donation pathways to P680(+).
Collapse
Affiliation(s)
| | - Gary W. Brudvig
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, U.S.A
| |
Collapse
|
7
|
Kawamori A, Ono TA, Ishii A, Nakazawa S, Hara H, Tomo T, Minagawa J, Bittl R, Dzuba SA. The functional sites of chlorophylls in D1 and D2 subunits of photosystem II identified by pulsed EPR. PHOTOSYNTHESIS RESEARCH 2005; 84:187-92. [PMID: 16049773 DOI: 10.1007/s11120-005-1000-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2004] [Accepted: 01/20/2005] [Indexed: 05/03/2023]
Abstract
The functional site of ChlZ, an auxiliary electron donor to P680+, was determined by pulsed ELDOR applied to a radical pair of YD * and Chlz+ in oriented PS II membranes from spinach. The radical-radical distance was determined to be 29.5 A and its direction was 50 degrees from the membrane normal, indicating that a chlorophyll on the D2 protein is responsible for the EPR Chlz+ signal. Spin polarized ESEEM (Electronin Spin Echo Envelop Modulation) of a 3Chl and QA - radical pair induced by a laser flash was observed in reaction center D1D2Cytb559 complex, in which QA was functionally reconstituted with DBMIB and reduced chemically. QA -ESEEM showed a characteristic oscillating time profile due to dipolar coupling with 3Chl. By fitting with the dipolar interaction parameters, the distance between 3Chl and QA - was determined to be 25.9 A, indicating that the accessory chlorophyll on the D1 protein is responsible for the 3Chl signal.
Collapse
Affiliation(s)
- A Kawamori
- School of Science and Technology, Kwansei Gakuin University, Sanda, Japan.
| | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Ishikita H, Knapp EW. Redox Potentials of Chlorophylls and β-Carotene in the Antenna Complexes of Photosystem II. J Am Chem Soc 2005; 127:1963-8. [PMID: 15701031 DOI: 10.1021/ja045058i] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Electron transfer (ET) processes in reaction centers (RC) of photosystem II (PSII) are prerequisites of oxygen generation. They are promoted by energy transfer from antenna to RC. Here, we calculated the redox potentials of chlorophylla/beta-carotene (Chla/Car) in PSII CP43/CP47 antenna complexes, solving the linearized Poisson-Boltzmann (LPB) equation based on the PSII crystal structure. The majority of antenna Chla redox potentials for reduction/oxidation were lower than those of RC Chla. Hence, ET events with excess electrons remain localized in the RC. Simultaneously antenna Chla can serve as an efficient cation sink to rereduce RC Chla if normal PSII function is inhibited. Especially three antenna Chla (Chl-47, Chl-18, and Chl-12) and two Car bridging the space between Chl(Z(D1)) and cytochrome (cyt) b559 have the same level of oxidation redox potential. Together with Chl(Z(D2)) they form an electron hole transfer pathway and temporary storage device guiding from the oxidized P680(+.) Chla to the cyt b559. This path may play a photoprotective role as efficient electron hole quencher.
Collapse
Affiliation(s)
- Hiroshi Ishikita
- Institute of Chemistry, Free University of Berlin, Takustrasse 6, D-14195 Berlin, Germany
| | | |
Collapse
|
9
|
MacArthur R, Brudvig GW. Location of EPR-Active Spins Buried in Proteins from the Simulation of the Spin−Lattice Relaxation Enhancement Caused by Dy(III) Complexes†. J Phys Chem B 2004. [DOI: 10.1021/jp0355713] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
10
|
Lakshmi KV, Poluektov OG, Reifler MJ, Wagner AM, Thurnauer MC, Brudvig GW. Pulsed high-frequency EPR study on the location of carotenoid and chlorophyll cation radicals in photosystem II. J Am Chem Soc 2003; 125:5005-14. [PMID: 12708850 DOI: 10.1021/ja0295671] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
When the primary electron-donation pathway from the water-oxidation complex in photosystem II (PS II) is inhibited, chlorophyll (Chl(Z) and Chl(D)), beta-carotene (Car) and cytochrome b(559) are alternate electron donors that are believed to function in a photoprotection mechanism. Previous studies have demonstrated that high-frequency EPR spectroscopy (at 130 GHz), together with deuteration of PS II, yields resolved Car(+) and Chl(+) EPR signals (Lakshmi et al. J. Phys. Chem. B 2000, 104, 10 445-10 448). The present study describes the use of pulsed high-frequency EPR spectroscopy to measure the location of the carotenoid and chlorophyll radicals relative to other paramagnetic cofactors in Synechococcus lividus PS II. The spin-lattice relaxation rates of the Car(+) and Chl(+) radicals are measured in manganese-depleted and manganese-depleted, cyanide-treated PS II; in these samples, the non-heme Fe(II) is high-spin (S = 2) and low-spin (S = 0), respectively. The Car(+) and Chl(+) radicals exhibit dipolar-enhanced relaxation rates in the presence of high-spin (S = 2) Fe(II) that are eliminated when the Fe(II) is low-spin (S = 0). The relaxation enhancements of the Car(+) and Chl(+) by the non-heme Fe(II) are smaller than the relaxation enhancement of Tyr(D)(*) and P(865)(+) by the non-heme Fe(II) in PS II and in the reaction center from Rhodobactersphaeroides, respectively, indicating that the Car(+)-Fe(II) and Chl(+)-Fe(II) distances are greater than the known Tyr(D)(*)-Fe(II) and P(865)(+)-Fe(II) distances. The Car(+) radical exhibits a greater relaxation enhancement by Fe(II) than the Chl(+) radical, consistent with Car being an earlier electron donor to P(680)(+) than Chl. On the basis of the distance estimates obtained in the present study and by analogy to carotenoid-binding sites in other pigment-protein complexes, possible binding sites are discussed for the Car cofactors in PS II. The relative location of Car(+) and Chl(+) radicals determined in this study provides valuable insight into the sequence of electron transfers in the alternate electron-donation pathways of PS II.
Collapse
Affiliation(s)
- K V Lakshmi
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, USA
| | | | | | | | | | | |
Collapse
|
11
|
Jankowiak R, Rätsep M, Hayes J, Zazubovich V, Picorel R, Seibert M, Small GJ. Primary Charge-Separation Rate at 5 K in Isolated Photosystem II Reaction Centers Containing Five and Six Chlorophyll a Molecules. J Phys Chem B 2003. [DOI: 10.1021/jp021787d] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- R. Jankowiak
- Ames Laboratory, USDOE, and Department of Chemistry, Iowa State University, Ames, Iowa 50011, Institute of Physics, University of Tartu, 51014 Tartu, Estonia, E. E. Aula Dei (CSIC), Apdo. 202, 50080 Zaragoza, Spain, and National Renewable Energy Laboratory, Golden, Colorado 80401
| | - M. Rätsep
- Ames Laboratory, USDOE, and Department of Chemistry, Iowa State University, Ames, Iowa 50011, Institute of Physics, University of Tartu, 51014 Tartu, Estonia, E. E. Aula Dei (CSIC), Apdo. 202, 50080 Zaragoza, Spain, and National Renewable Energy Laboratory, Golden, Colorado 80401
| | - J. Hayes
- Ames Laboratory, USDOE, and Department of Chemistry, Iowa State University, Ames, Iowa 50011, Institute of Physics, University of Tartu, 51014 Tartu, Estonia, E. E. Aula Dei (CSIC), Apdo. 202, 50080 Zaragoza, Spain, and National Renewable Energy Laboratory, Golden, Colorado 80401
| | - V. Zazubovich
- Ames Laboratory, USDOE, and Department of Chemistry, Iowa State University, Ames, Iowa 50011, Institute of Physics, University of Tartu, 51014 Tartu, Estonia, E. E. Aula Dei (CSIC), Apdo. 202, 50080 Zaragoza, Spain, and National Renewable Energy Laboratory, Golden, Colorado 80401
| | - R. Picorel
- Ames Laboratory, USDOE, and Department of Chemistry, Iowa State University, Ames, Iowa 50011, Institute of Physics, University of Tartu, 51014 Tartu, Estonia, E. E. Aula Dei (CSIC), Apdo. 202, 50080 Zaragoza, Spain, and National Renewable Energy Laboratory, Golden, Colorado 80401
| | - M. Seibert
- Ames Laboratory, USDOE, and Department of Chemistry, Iowa State University, Ames, Iowa 50011, Institute of Physics, University of Tartu, 51014 Tartu, Estonia, E. E. Aula Dei (CSIC), Apdo. 202, 50080 Zaragoza, Spain, and National Renewable Energy Laboratory, Golden, Colorado 80401
| | - G. J. Small
- Ames Laboratory, USDOE, and Department of Chemistry, Iowa State University, Ames, Iowa 50011, Institute of Physics, University of Tartu, 51014 Tartu, Estonia, E. E. Aula Dei (CSIC), Apdo. 202, 50080 Zaragoza, Spain, and National Renewable Energy Laboratory, Golden, Colorado 80401
| |
Collapse
|
12
|
|
13
|
Wang J, Gosztola D, Ruffle SV, Hemann C, Seibert M, Wasielewski MR, Hille R, Gustafson TL, Sayre RT. Functional asymmetry of photosystem II D1 and D2 peripheral chlorophyll mutants of Chlamydomonas reinhardtii. Proc Natl Acad Sci U S A 2002; 99:4091-6. [PMID: 11904453 PMCID: PMC122653 DOI: 10.1073/pnas.062056899] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2001] [Accepted: 01/31/2002] [Indexed: 11/18/2022] Open
Abstract
The peripheral accessory chlorophylls (Chls) of the photosystem II (PSII) reaction center (RC) are coordinated by a pair of symmetry-related histidine residues (D1-H118 and D2-H117). These Chls participate in energy transfer from the proximal antennae complexes (CP43 and CP47) to the RC core chromophores. In addition, one or both of the peripheral Chls are redox-active and participate in a low-quantum-yield electron transfer cycle around PSII. We demonstrate that conservative mutations of the D2-H117 residue result in decreased Chl fluorescence quenching efficiency attributed to reduced accumulation of the peripheral accessory Chl cation, Chl(Z)(+). In contrast, identical symmetry-related mutations at residue D1-H118 had no effect on Chl fluorescence yield or quenching kinetics. Mutagenesis of the D2-H117 residue also altered the line width of the Chl(Z)(+) EPR signal, but the line shape of the D1-H118Q mutant remained unchanged. The D1-H118 and D2-H117 mutations also altered energy transfer properties in PSII RCs. Unlike wild type or the D1-H118Q mutant, D2-H117N RCs exhibited a reduced CD doublet in the red region of Chl absorbance band, indicative of reduced energetic coupling between P680 and the peripheral accessory Chl. In addition, transient absorption measurements of D2-H117N RCs, excited on the blue side of the Chl absorbance band, exhibited a ( approximately 400 fs) pheophytin Q(X) band bleach lifetime component not seen in wild-type or D1-H118Q RCs. The origin of this component may be related to delayed fast-energy equilibration of the excited state between the core pigments of this mutant.
Collapse
Affiliation(s)
- Jun Wang
- Department of Plant Biology, Ohio State University, Columbus, OH 43210, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Diner BA, Rappaport F. Structure, dynamics, and energetics of the primary photochemistry of photosystem II of oxygenic photosynthesis. ANNUAL REVIEW OF PLANT BIOLOGY 2002; 53:551-80. [PMID: 12221988 DOI: 10.1146/annurev.arplant.53.100301.135238] [Citation(s) in RCA: 256] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Recent progress in two-dimensional and three-dimensional electron and X-ray crystallography of Photosystem II (PSII) core complexes has led to major advances in the structural definition of this integral membrane protein complex. Despite the overall structural and kinetic similarity of the PSII reaction centers to their purple non-sulfur photosynthetic bacterial homologues, the different cofactors and subtle differences in their spatial arrangement result in significant differences in the energetics and mechanism of primary charge separation. In this review we discuss some of the recent spectroscopic, structural, and mutagenic work on the primary and secondary electron transfer reactions in PSII, stressing what is experimentally novel, what new insights have appeared, and where questions of interpretation remain.
Collapse
Affiliation(s)
- Bruce A Diner
- CR&D, Experimental Station, E. I. du Pont de Nemours & Co., Wilmington, Delaware 19880-0173, USA.
| | | |
Collapse
|
15
|
Determination of Distances Based on T1 and Tm Effects. DISTANCE MEASUREMENTS IN BIOLOGICAL SYSTEMS BY EPR 2002. [DOI: 10.1007/0-306-47109-4_8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
|
16
|
Lakshmi KV, Brudvig GW. Pulsed electron paramagnetic resonance methods for macromolecular structure determination. Curr Opin Struct Biol 2001; 11:523-31. [PMID: 11785751 DOI: 10.1016/s0959-440x(00)00242-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Pulsed electron paramagnetic resonance (EPR) distance measurement techniques target macromolecular structure elucidation at both the local and global level. Recent developments in pulse microwave technology and high-field EPR have led to the development of a variety of pulsed EPR distance measurement techniques. These methods have emerged as powerful tools for the determination of structure/function relationships in macromolecular systems. In this review article, we discuss recent applications of long-range and short-range EPR distance measurements.
Collapse
Affiliation(s)
- K V Lakshmi
- Department of Chemistry, Yale University, New Haven, CT 06520, USA.
| | | |
Collapse
|
17
|
|
18
|
Rhee KH. Photosystem II: the solid structural era. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 2001; 30:307-28. [PMID: 11340062 DOI: 10.1146/annurev.biophys.30.1.307] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Understanding the precise role of photosystem II as an element of oxygenic photosynthesis requires knowledge of the molecular structure of this membrane protein complex. The past few years have been particularly exciting because the structural era of the plant photosystem II has begun. Although the atomic structure has yet to be determined, the map obtained at 6 A resolution by electron crystallography allows assignment of the key reaction center subunits with their associated pigment molecules. In the following, we first review the structural details that have recently emerged and then discuss the primary and secondary photochemical reaction pathways. Finally, in an attempt to establish the evolutionary link between the oxygenic and the anoxygenic photosynthesis, a framework structure common to all photosynthetic reaction centers has been defined, and the implications have been described.
Collapse
Affiliation(s)
- K H Rhee
- Laboratory of Molecular Biology, Medical Research Council, Hills Road, Cambridge, CB2 2QH, United Kingdom.
| |
Collapse
|
19
|
Abstract
Pulsed electron paramagnetic resonance (EPR) methods such as ESEEM, PELDOR, relaxation time measurements, transient EPR, high-field/high-frequency EPR, and pulsed ENDOR, have been used successfully to investigate the local structure and dynamics of paramagnetic centers in biological samples. These methods allow different contributions to the EPR spectra to be distinguished and can help unravel complicated EPR spectra consisting of overlapping resonance lines, as are often found in disordered protein samples. The basic principles, specific potentials, technical requirements, and limitations of these advanced EPR techniques will be reviewed together with recent applications to metal centers, organic radicals, and spin labels in proteins.
Collapse
Affiliation(s)
- T Prisner
- Institute for Physical and Theoretical Chemistry, J. W. Goethe-University Frankfurt, Marie-Curie-Strasse 11, Frankfurt am Main, D-60439 Germany.
| | | | | |
Collapse
|
20
|
Abstract
The input of solar energy into photosynthesis, and thence into the biosphere, occurs via chlorophyll-containing proteins known as reaction centres. There are two kinds of reaction centre in oxygenic photosynthesis: photosystem I (PSI) and photosystem II (PSII). The PSII reaction centre, alias the oxygen-evolving enzyme, the water-oxidizing complex or the water-plastoquinone photo-oxidoreductase, has now been crystallized and its structure solved to a resolution of 3.8 A.
Collapse
Affiliation(s)
- A W Rutherford
- Service de Bioénergétique, CNRS URA 2096, CEA Saclay, F-91191, Gif-sur-Yvette, France.
| | | |
Collapse
|
21
|
Kuroiwa S, Tonaka M, Kawamori A, Akabori K. The position of cytochrome b(559) relative to Q(A) in photosystem II studied by electron-electron double resonance (ELDOR). BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1460:330-7. [PMID: 11106773 DOI: 10.1016/s0005-2728(00)00199-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The electron-electron double resonance (ELDOR) method was applied to measure the dipole interaction between cytochrome (Cyt) b(+)(559) and the primary acceptor quinone (Q(-)(A)), observed at g=2.0045 with the peak to peak width of about 9 G, in Photosystem II (PS II) in which the non-heme Fe(2+) was substituted by Zn(2+). The paramagnetic centers of Cyt b(+)(559)Y(D)Q(-)(A) were trapped by illumination at 273 K for 8 min, followed by dark adaptation for 3 min and freezing into 77 K. The distance between the pair Cyt b(+)(559)-Q(-)(A) was estimated from the dipole interaction constant fitted to the observed ELDOR time profile to be 40+/-1 A. In the membrane oriented PS II particles the angle between the vector from Q(A) to Cyt b(559) and the membrane normal was determined to be 80+/-5 degrees. The position of Cyt b(559) relative to Q(A) suggests that the heme plane is located on the stromal side of the thylakoid membrane. ELDOR was not observed for Cyt b(+)(559) Y(D) spin pair, suggesting the distance between them is more than 50 A.
Collapse
Affiliation(s)
- S Kuroiwa
- Faculty of Science, Kwansei Gakuin University, Uegahara 1-1-155, Nishinomiya 662-8501, Japan
| | | | | | | |
Collapse
|
22
|
Faller P, Rutherford AW, Un S. High-Field EPR Study of Carotenoid•+ and the Angular Orientation of Chlorophyll z•+ in Photosystem II. J Phys Chem B 2000. [DOI: 10.1021/jp0027344] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Peter Faller
- Département de Biologie Cellulaire et Moléculaire, Section de Bioénergétique, CNRS URA 2096, CEA Saclay, F-91191 Gif-sur-Yvette, France
| | - A. William Rutherford
- Département de Biologie Cellulaire et Moléculaire, Section de Bioénergétique, CNRS URA 2096, CEA Saclay, F-91191 Gif-sur-Yvette, France
| | - Sun Un
- Département de Biologie Cellulaire et Moléculaire, Section de Bioénergétique, CNRS URA 2096, CEA Saclay, F-91191 Gif-sur-Yvette, France
| |
Collapse
|
23
|
Jankowiak R, Rätsep M, Picorel R, Seibert M, Small GJ. Excited States of the 5-Chlorophyll Photosystem II Reaction Center. J Phys Chem B 1999. [DOI: 10.1021/jp9906738] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- R. Jankowiak
- Ames Laboratory−U.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011, E. E. Aula Dei, CSIC, Apdo. 202, 50080-Zaragoza, Spain, and National Renewable Energy Laboratory, Golden, Colorado 80401
| | - M. Rätsep
- Ames Laboratory−U.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011, E. E. Aula Dei, CSIC, Apdo. 202, 50080-Zaragoza, Spain, and National Renewable Energy Laboratory, Golden, Colorado 80401
| | - R. Picorel
- Ames Laboratory−U.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011, E. E. Aula Dei, CSIC, Apdo. 202, 50080-Zaragoza, Spain, and National Renewable Energy Laboratory, Golden, Colorado 80401
| | - M. Seibert
- Ames Laboratory−U.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011, E. E. Aula Dei, CSIC, Apdo. 202, 50080-Zaragoza, Spain, and National Renewable Energy Laboratory, Golden, Colorado 80401
| | - G. J. Small
- Ames Laboratory−U.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011, E. E. Aula Dei, CSIC, Apdo. 202, 50080-Zaragoza, Spain, and National Renewable Energy Laboratory, Golden, Colorado 80401
| |
Collapse
|
24
|
Deligiannakis Y, Rutherford AW. Reaction centre photochemistry in cyanide-treated photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1365:354-362. [PMID: 9757079 DOI: 10.1016/s0005-2728(98)00091-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
EPR was used to study the triplet state of chlorophyll generated by radical pair recombination in the photosystem II (PSII) reaction centre. The spin state of the non-haem Fe2+ was varied using the CN--binding method (Y. Sanakis, V. Petrouleas, B.A. Diner, Biochemistry 33 (1994) 9922-9928) and the redox state of the quinone acceptor (QA) was changed from semi-reduced to fully reduced (F.J.E. van Mieghem, W. Nitschke, P. Mathis, A.W. Rutherford, Biochim. Biophys. Acta 977 (1989) 207-214). It was found that the triplet was not detectable using continuous wave EPR when QA- was present irrespective of the spin-state of the Fe2+. It was also found that the triplet state became detectable by EPR when the semiquinone was removed (by reduction to the quinol) and that the triplet observed was not influenced by the spin state of the Fe2+. Since it is known from earlier work that the EPR detection of the triplet reflects a change in the triplet lifetime, it is concluded that the redox state of the quinone determines the triplet lifetime (at least in terms of its detectability by continuous wave EPR) and that the magnetic state of the iron, (through the weakly exchange-coupled QA- Fe2+ complex) is not a determining factor. In addition, we looked for polarisation transfer from the radical pair to QA- in PSII where the Fe2+ was low spin. Such polarisation is seen in bacterial reaction centres under comparable conditions. In PSII, however, we were unable to find evidence for such polarisation of the semiquinone. It is suggested that both the short triplet lifetime in the presence of QA- and the lack of polarised QA- might be explained in terms of the electron transfer mechanism for triplet quenching involving the semiquinone which was proposed previously (F.J.E. van Mieghem, K. Brettel, B. Hillmann, A. Kamlowski, A.W. Rutherford, E. Schlodder, Biochemistry 34 (1995) 4798-4813). It is suggested that this mechanism may occur in PSII (but not in purple bacterial reaction centres) due the triplet-bearing chlorophyll being adjacent to the pheophytin at low temperature as suggested from structural studies (F.J.E. van Mieghem, K. Satoh, A.W. Rutherford, Biochim. Biophys. Acta 1058 (1992) 379-385).
Collapse
Affiliation(s)
- Y Deligiannakis
- Section de Bioénergetique, (URA CNRS 2096) Département de Biologie Cellulaire et Moleculaire, CEA Saclay, 91911 Gif-sur-Yvette, France
| | | |
Collapse
|
25
|
Cua A, Stewart DH, Brudvig GW, Bocian DF. Selective Resonance Raman Scattering from Chlorophyll Z in Photosystem II via Excitation into the Near-Infrared Absorption Band of the Cation. J Am Chem Soc 1998. [DOI: 10.1021/ja980207g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Agnes Cua
- Department of Chemistry, University of California Riverside, California 92521-0403 Department of Chemistry, Yale University New Haven, Connecticut 06520-8107
| | - David H. Stewart
- Department of Chemistry, University of California Riverside, California 92521-0403 Department of Chemistry, Yale University New Haven, Connecticut 06520-8107
| | - Gary W. Brudvig
- Department of Chemistry, University of California Riverside, California 92521-0403 Department of Chemistry, Yale University New Haven, Connecticut 06520-8107
| | - David F. Bocian
- Department of Chemistry, University of California Riverside, California 92521-0403 Department of Chemistry, Yale University New Haven, Connecticut 06520-8107
| |
Collapse
|
26
|
Determination of distances from tyrosine D to QA and chlorophyllZ in photosystem II studied by '2+1' pulsed EPR. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1363:187-98. [PMID: 9518607 DOI: 10.1016/s0005-2728(97)00100-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A '2+1' pulse sequence electron spin echo (ESE) method was applied to measure the dipole interactions between the tyrosine YD+ and QA- in Photosystem II (PS II). In a CN--treated PS II, QA- EPR signal was observed at g=2.0045 position, because the non-heme Fe(II) was converted into a low-spin (S=0) state. The radical pair of YD+QA- was trapped by illumination for 8 min at 273 K, followed by dark adaptation for 3 min and freezing into 77 K. By using a proton matrix ENDOR, these trapped radicals were confirmed to be YD+ and QA-, respectively. The distance between the radical pair was estimated from the dipole interaction constant fitted to the observed '2+1' ESE time profile. The distance of YD+-QA- is determined to be 38.8+/-1.1 A. The magnetic dipole interaction between YD+ and ChlZ+ was determined in a Tris-treated PS II in which ChlZ+ was generated by illumination at 200 K for 10 min. The YD+-ChlZ+ distance was estimated to be 29.4+/-0.5 A. Copyright 1998 Elsevier Science B.V.
Collapse
|
27
|
Deligiannakis Y, Hanley J, Rutherford AW. Spin-lattice relaxation of the phyllosemiquinone radical of photosystem I. Biochemistry 1998; 37:3329-36. [PMID: 9521653 DOI: 10.1021/bi971297p] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The spin-lattice relaxation time (T1) of the phyllosemiquinone anion radical, A1-, of the photosystem I (PSI) reaction center, were measured between 4.5 and 85 K by electron spin-echo spectroscopy. The selective removal of the iron-sulfur centers, FA, FB, and FX, from PSI allowed the measurement of the intrinsic T1 of the A1- radical. The temperature dependence of the intrinsic (T1)-1 for A1- was found to be approximately T1.3 +/- 0.1. The spin-lattice relaxation of the reduced form of iron-sulfur center FX was also measured at low temperatures, in FA/FB-depleted PSI membranes. It was found that the fast-relaxing FX center enhances the spin-lattice relaxation of the phyllosemiquinone due to dipolar coupling. The effect of the reduced forms of FA/FB on the T1 of the phyllosemiquinone was minor compared to the effect of FX. By analyzing the data with a dipolar model in the light of limitations imposed by other information present in the literature, the distance between the phyllosemiquinone and FX in PSI is estimated to be 14.8 +/- 4 A.
Collapse
Affiliation(s)
- Y Deligiannakis
- Section de Bioénergétique (URA CNRS 2096), Département de Biologie Cellulaire et Moléculaire, CEA Saclay, Gif-sur-Yvette, France
| | | | | |
Collapse
|
28
|
Burchfield JM, Du JL, More KM, Eaton SS, Eaton GR. Enhancement of electron spin relaxation rates of metalloporphyrins due to interaction with a faster relaxing metal bound to an appended bipyridyl. Inorganica Chim Acta 1997. [DOI: 10.1016/s0020-1693(97)05590-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
29
|
Campbell KA, Peloquin JM, Diner BA, Tang XS, Chisholm DA, Britt RD. The τ-Nitrogen of D2 Histidine 189 is the Hydrogen Bond Donor to the Tyrosine Radical YD• of Photosystem II. J Am Chem Soc 1997. [DOI: 10.1021/ja9706155] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kristy A. Campbell
- Department of Chemistry University of California Davis, California 95616 Central Research and Development Department Experimental Station, P.O. Box 80173 E. I. du Pont De Nemours & Company Wilmington, Delaware 19880-0173
| | - Jeffrey M. Peloquin
- Department of Chemistry University of California Davis, California 95616 Central Research and Development Department Experimental Station, P.O. Box 80173 E. I. du Pont De Nemours & Company Wilmington, Delaware 19880-0173
| | - Bruce A. Diner
- Department of Chemistry University of California Davis, California 95616 Central Research and Development Department Experimental Station, P.O. Box 80173 E. I. du Pont De Nemours & Company Wilmington, Delaware 19880-0173
| | - Xiao-Song Tang
- Department of Chemistry University of California Davis, California 95616 Central Research and Development Department Experimental Station, P.O. Box 80173 E. I. du Pont De Nemours & Company Wilmington, Delaware 19880-0173
| | - Dexter A. Chisholm
- Department of Chemistry University of California Davis, California 95616 Central Research and Development Department Experimental Station, P.O. Box 80173 E. I. du Pont De Nemours & Company Wilmington, Delaware 19880-0173
| | - R. David Britt
- Department of Chemistry University of California Davis, California 95616 Central Research and Development Department Experimental Station, P.O. Box 80173 E. I. du Pont De Nemours & Company Wilmington, Delaware 19880-0173
| |
Collapse
|
30
|
EPR and ESEEM study of the plastoquinone anion radical QA−. in photosystem II treated at high pH. Chem Phys Lett 1997. [DOI: 10.1016/s0009-2614(97)00390-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
31
|
Deligiannakis Y, Rutherford AW. Spin-lattice relaxation of the pheophytin, Pheo-, radical of photosystem II. Biochemistry 1996; 35:11239-46. [PMID: 8784177 DOI: 10.1021/bi9608471] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The spin-lattice relaxation times (T1) of the pheophytin anion radical, Pheo-, of the PSII reaction center, were measured between 5 and 80 K by electron spin-echo spectroscopy. The Pheo- was studied in Mn-depleted PSII reaction centers in which the primary quinone, QA, was doubly reduced. The selective conversion of the non-heme Fe2+ into its low-spin (S = O) state, in CN-treated PSII, allowed the measurement of the intrinsic T1 of the Pheo- radical. The temperature dependence of the intrinsic (T1)-1 was found to be approximately T1.3 +/- 0.1. In Mn-depleted PSII membranes the high-spin (S = 2) non-heme iron, enhances the spin-lattice relaxation of Pheo-. By analyzing the data with a dipolar model, the dipolar interaction (k1d) between the Pheo and the Fe2+ (S = 2) is estimated over the temperature range 5-80 K. Comparison with the dipolar coupling between the iron and the tyrosine, YD+, shows that the Pheo is much closer to the iron than the YD+ in the PSII reaction center. By scaling the reported Fe(2+)-YD+ distance by the ratio [k1dPheo-]/[k1dYD+], we estimate the Fe(2+)-Pheo- distance in PSII to be 20 +/- 4.2 A. This distance is close to the Fe(2+)-BPheo- distance in the bacterial reaction center, and this result provides further evidence that the acceptor sides of the reaction centers in PSII and bacteria are homologous.
Collapse
Affiliation(s)
- Y Deligiannakis
- Section de Bioénergétique (URA CNRS 2096), Département de Biologie Cellulaire et Moléculaire, CEA Saclay, Gif-sur-Yvette, France
| | | |
Collapse
|
32
|
Nugent JH. Oxygenic photosynthesis. Electron transfer in photosystem I and photosystem II. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 237:519-31. [PMID: 8647094 DOI: 10.1111/j.1432-1033.1996.00519.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Photosystems I and II drive oxygenic photosynthesis. This requires biochemical systems with remarkable properties, allowing these membrane-bound pigment-protein complexes to oxidise water and produce NAD(P)H. The protein environment provides a scaffold in the membrane on which cofactors are placed at optimum distance and orientation, ensuring a rapid, efficient trapping and conversion of light energy. The polypeptide core also tunes the redox potentials of cofactors and provides for unidirectional progress of various reaction steps. The electron transfer pathways use a variety of inorganic and organic cofactors, including amino acids. This review sets out some of the current ideas and data on the cofactors and polypeptides of photosystems I and II.
Collapse
Affiliation(s)
- J H Nugent
- Department of Biology, University College London, UK
| |
Collapse
|
33
|
|
34
|
Bumann D, Oesterhelt D. Destruction of a single chlorophyll is correlated with the photoinhibition of photosystem II with a transiently inactive donor side. Proc Natl Acad Sci U S A 1995; 92:12195-9. [PMID: 11607621 PMCID: PMC40323 DOI: 10.1073/pnas.92.26.12195] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pigments destroyed during photoinhibition of water-splitting photosystem II core complexes from the green alga Chlamydomonas reinhardtii were studied. Under conditions of a transiently inactivated donor side, illumination leads to an irreversible inhibition of the electron transfer at the donor side that is paralleled by the destruction of chlorophylls a absorbing maximally around 674 and 682 nm. The observed stochiometry of 1 +/- 0.1 destroyed chlorophyll per inhibited photosystem II suggests that chlorophyll destruction could be the primary photodamage causing the inhibition of photosystem II under these conditions.
Collapse
Affiliation(s)
- D Bumann
- Department of Membrane Biochemistry, Max Planck Institute for Biochemistry, Martinsried, Germany
| | | |
Collapse
|
35
|
Noguchi T, Inoue Y. Molecular interactions of the redox-active accessory chlorophyll on the electron-donor side of photosystem II as studied by Fourier transform infrared spectroscopy. FEBS Lett 1995; 370:241-4. [PMID: 7656985 DOI: 10.1016/0014-5793(95)00833-u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A Fourier transform infrared (FTIR) difference spectrum upon photooxidation of the accessory chlorophyll (Chlz) of photosystem II (PS II) was obtained at 210 K with Mn-depleted PS II membranes in the presence of fericyanide and silicomolybdate. The observed Chlz+/Chlz spectrum showed two differential bands at 1747/1736 and 1714/1684 cm-1. The former was assigned to the free carbomethoxy C = 0 and the latter to the keto C = 0 that is hydrogen-bonded or in a highly polar environment. Also, the negative 1614 cm-1 band assignable to the macrocycle mode indicated 5-coordination of the central Mg. The negative 1660 cm-1 band, possibly due to the strongly hydrogen-bonded keto C = 0, may suggest oxidation of one more Chlz, although an alternative assignment, the amide I mode of proteins perturbed by Chlz oxidation, is also possible.
Collapse
Affiliation(s)
- T Noguchi
- Photosynthesis Research laboratory, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan
| | | |
Collapse
|
36
|
Eijckelhoff C, Dekker JP. Determination of the pigment stoichiometry of the photochemical reaction center of photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1995. [DOI: 10.1016/0005-2728(95)00055-n] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
37
|
Temperature dependent hole burning of the 684 nm chlorophyll a of the isolated reaction center of Photosystem II: confirmation of the linker model. Chem Phys 1995. [DOI: 10.1016/0301-0104(95)00076-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|