Publications
277 results found
Kato M, Cardona T, Rutherford AW, et al., 2012, Photoelectrochemical Water Oxidation with Photosystem II Integrated in a Mesoporous; Indium Tin Oxide Electrode, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 134, Pages: 8332-8335, ISSN: 0002-7863
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- Citations: 165
Rutherford AW, Osyczka A, Rappaport F, 2012, Back-reactions, short-circuits, leaks and other energy wasteful reactions in biological electron transfer: Redox tuning to survive life in O(2)., FEBS Lett, Vol: 586, Pages: 603-616
The energy-converting redox enzymes perform productive reactions efficiently despite the involvement of high energy intermediates in their catalytic cycles. This is achieved by kinetic control: with forward reactions being faster than competing, energy-wasteful reactions. This requires appropriate cofactor spacing, driving forces and reorganizational energies. These features evolved in ancestral enzymes in a low O(2) environment. When O(2) appeared, energy-converting enzymes had to deal with its troublesome chemistry. Various protective mechanisms duly evolved that are not directly related to the enzymes' principal redox roles. These protective mechanisms involve fine-tuning of reduction potentials, switching of pathways and the use of short circuits, back-reactions and side-paths, all of which compromise efficiency. This energetic loss is worth it since it minimises damage from reactive derivatives of O(2) and thus gives the organism a better chance of survival. We examine photosynthetic reaction centres, bc(1) and b(6)f complexes from this view point. In particular, the evolution of the heterodimeric PSI from its homodimeric ancestors is explained as providing a protective back-reaction pathway. This "sacrifice-of-efficiency-for-protection" concept should be generally applicable to bioenergetic enzymes in aerobic environments.
Cardona T, Sedoud A, Cox N, et al., 2012, Charge separation in Photosystem II: A comparative and evolutionary overview, BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS, Vol: 1817, Pages: 26-43, ISSN: 0005-2728
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- Citations: 252
Hideg E, Deak Z, Hakala-Yatkin M, et al., 2011, Pure forms of the singlet oxygen sensors TEMP and TEMPD do not inhibit Photosystem II, BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS, Vol: 1807, Pages: 1658-1661, ISSN: 0005-2728
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- Citations: 36
Cox N, Rapatskiy L, Su J-H, et al., 2011, Effect of Ca<SUP>2+</SUP>/Sr<SUP>2+</SUP> Substitution on the Electronic Structure of the Oxygen-Evolving Complex of Photosystem II: A Combined Multifrequency EPR, <SUP>55</SUP>Mn-ENDOR, and DFT Study of the S<sub>2</sub> State (vol 133, pg 3635, 2011), JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 133, Pages: 14149-14149, ISSN: 0002-7863
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- Citations: 6
Sedoud A, Cox N, Sugiura M, et al., 2011, Semiquinone-iron complex of photosystem II: EPR signals assigned to the low-field edge of the ground state doublet of QA•-Fe2+ and QB•-Fe2+., Biochemistry, Vol: 50, Pages: 6012-6021
The quinone-iron complex of the electron acceptor complex of Photosystem II was studied by EPR spectroscopy in Thermosynechococcus elongatus. New g ∼ 2 features belonging to the EPR signal of the semiquinone forms of the primary and secondary quinone, i.e., Q(A)(•-)Fe(2+) and Q(B)(•-)Fe(2+), respectively, are reported. In previous studies, these signals were missed because they were obscured by the EPR signal arising from the stable tyrosyl radical, TyrD(•). When the TyrD(•) signal was removed, either by chemical reduction or by the use of a mutant lacking TyrD, the new signals dominated the spectrum. For Q(A)(•-)Fe(2+), the signal was formed by illumination at 77 K or by sodium dithionite reduction in the dark. For Q(B)(•-)Fe(2+), the signal showed the characteristic period-of-two variations in its intensity when generated by a series of laser flashes. The new features showed relaxation characteristics comparable to those of the well-known features of the semiquinone-iron complexes and showed a temperature dependence consistent with an assignment to the low-field edge of the ground state doublet of the spin system. Spectral simulations are consistent with this assignment and with the current model of the spin system. The signal was also present in Q(B)(•-)Fe(2+) in plant Photosystem II, but in plants, the signal was not detected in the Q(A)(•-)Fe(2+) state.
Su J-H, Cox N, Ames W, et al., 2011, The electronic structures of the <i>S</i><sub>2</sub> states of the oxygen-evolving complexes of photosystem II in plants and cyanobacteria in the presence and absence of methanol, BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS, Vol: 1807, Pages: 829-840, ISSN: 0005-2728
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- Citations: 72
Herrero C, Quaranta A, Leibl W, et al., 2011, Artificial photosynthetic systems. Using light and water to provide electrons and protons for the synthesis of a fuel, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 4, Pages: 2353-2365, ISSN: 1754-5692
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- Citations: 93
Herrero C, Quaranta A, Protti S, et al., 2011, Light-Driven Activation of the [H<sub>2</sub>O(terpy)Mn<SUP>III</SUP>-μ-(O<sub>2</sub>)-Mn<SUP>IV</SUP>(terpy)OH<sub>2</sub>] Unit in a Chromophore-Catalyst Complex, CHEMISTRY-AN ASIAN JOURNAL, Vol: 6, Pages: 1335-1339, ISSN: 1861-4728
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- Citations: 21
Cox N, Rapatskiy L, Su J-H, et al., 2011, Effect of Ca<SUP>2+</SUP>/Sr<SUP>2+</SUP> Substitution on the Electronic Structure of the Oxygen-Evolving Complex of Photosystem II: A Combined Multifrequency EPR, <SUP>55</SUP>Mn-ENDOR, and DFT Study of the S<sub>2</sub> State, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 133, Pages: 3635-3648, ISSN: 0002-7863
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- Citations: 188
Guerrero F, Sedoud A, Kirilovsky D, et al., 2011, A High Redox Potential Form of Cytochrome <i>c</i><sub>550</sub> in Photosystem II from <i>Thermosynechococcus elongatus</i>, JOURNAL OF BIOLOGICAL CHEMISTRY, Vol: 286, Pages: 5985-5994, ISSN: 0021-9258
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- Citations: 12
Ido K, Gross CM, Guerrero F, et al., 2011, High and low potential forms of the Q<sub>A</sub> quinone electron acceptor in Photosystem II of <i>Thermosynechococcus elongatus</i> and spinach, JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY, Vol: 104, Pages: 154-157, ISSN: 1011-1344
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- Citations: 23
Sedoud A, Kastner L, Cox N, et al., 2011, Effects of formate binding on the quinone-iron electron acceptor complex of photosystem II., Biochim Biophys Acta, Vol: 1807, Pages: 216-226, ISSN: 0006-3002
EPR was used to study the influence of formate on the electron acceptor side of photosystem II (PSII) from Thermosynechococcus elongatus. Two new EPR signals were found and characterized. The first is assigned to the semiquinone form of Q(B) interacting magnetically with a high spin, non-heme-iron (Fe²(+), S=2) when the native bicarbonate/carbonate ligand is replaced by formate. This assignment is based on several experimental observations, the most important of which were: (i) its presence in the dark in a significant fraction of centers, and (ii) the period-of-two variations in the concentration expected for Q(B)(•-) when PSII underwent a series of single-electron turnovers. This signal is similar but not identical to the well-know formate-modified EPR signal observed for the Q(A)(•-)Fe²(+) complex (W.F.J. Vermaas and A.W. Rutherford, FEBS Lett. 175 (1984) 243-248). The formate-modified signals from Q(A)(•-)Fe²(+) and Q(B)(•-)Fe²(+) are also similar to native semiquinone-iron signals (Q(A)(•-)Fe²(+)/Q(B)(•-)Fe²(+)) seen in purple bacterial reaction centers where a glutamate provides the carboxylate ligand to the iron. The second new signal was formed when Q(A)(•-) was generated in formate-inhibited PSII when the secondary acceptor was reduced by two electrons. While the signal is reminiscent of the formate-modified semiquinone-iron signals, it is broader and its main turning point has a major sub-peak at higher field. This new signal is attributed to the Q(A)(•-)Fe²(+) with formate bound but which is perturbed when Q(B) is fully reduced, most likely as Q(B)H₂ (or possibly Q(B)H(•-) or Q(B)(²•-)). Flash experiments on formate-inhibited PSII monitoring these new EPR signals indicate that the outcome of charge separation on the first two flashes is not greatly modified by formate. However on the third flash and subsequent flashes, the modified Q(A)(•-)Fe²(+)Q(B)H₂ sign
Hughes JL, Cox N, Rutherford AW, et al., 2010, D1 protein variants in Photosystem II from <i>Thermosynechococcus elongatus</i> studied by low temperature optical spectroscopy, BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS, Vol: 1797, Pages: 11-19, ISSN: 0005-2728
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- Citations: 20
Vittadello M, Gorbunov MY, Mastrogiovanni DT, et al., 2010, Photoelectron Generation by Photosystem II Core Complexes Tethered to Gold Surfaces, CHEMSUSCHEM, Vol: 3, Pages: 471-475, ISSN: 1864-5631
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- Citations: 29
Cox N, Hughes J, Rutherford AW, et al., 2010, On the assignment of PSHB in D1/D2/cytb<sub>559</sub> reaction centers, PROCEEDINGS OF THE TENTH INTERNATIONAL MEETING ON HOLE BURNING, SINGLE MOLECULE AND RELATED SPECTROSCOPIES, Vol: 3, Pages: 1601-1605, ISSN: 1875-3892
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- Citations: 8
Herrero C, Hughes JL, Quaranta A, et al., 2010, Intramolecular light induced activation of a Salen-Mn<SUP>III</SUP> complex by a ruthenium photosensitizer, CHEMICAL COMMUNICATIONS, Vol: 46, Pages: 7605-7607, ISSN: 1359-7345
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- Citations: 30
Cox N, Jin L, Jaszewski A, et al., 2009, The Semiquinone-Iron Complex of Photosystem II: Structural Insights from ESR and Theoretical Simulation; Evidence that the Native Ligand to the Non-Heme Iron Is Carbonate, BIOPHYSICAL JOURNAL, Vol: 97, Pages: 2024-2033, ISSN: 0006-3495
The semiquinone-iron complex of photosystem II was studied using electron spin resonance (ESR) spectroscopy and density functional theory calculations. Two forms of the signal were investigated: 1), the native g similar to 1.9 form; and 2), the g similar to 1.84 form, which is well known in purple bacterial reaction centers and occurs in photosystem 11 when treated with formate. The g similar to 1.9 form shows low- and high-field edges at g similar to 3.5 and g < 0.8, respectively, and resembles the g similar to 1.84 form in terms of shape and width. Both types of ESR signal were simulated using the theoretical approach used previously for the BRC complex, a spin Hamiltonian formalism in which the semiquinone radical magnetically interacts (J similar to 1 cm(-1)) with the nearby high-spin Fe(2+). The two forms of ESR signal differ mainly by an axis rotation of the exchange coupling tensor (J) relative to the zero-field tensor (D) and a small increase in the zero-field parameter D (similar to 6 cm(-1)). Density functional theory calculations were conducted on model semiquinone-iron systems to identify the physical nature of these changes. The replacement of formate (or glutamate in the bacterial reaction centers) by bicarbonate did not result in changes in the coupling environment. However, when carbonate (CO(3)(2-)) was used instead of bicarbonate, the exchange and zero-field tensors did show changes that matched those obtained from the spectral simulations. This indicates that 1), the doubly charged carbonate ion is responsible for the g similar to 1.9 form of the semiquinone-iron signal; and 2), carbonate, rather than bicarbonate, is the ligand to the iron.
Cox N, Hughes JL, Steffen R, et al., 2009, Identification of the Q<i><sub>Y</sub></i> Excitation of the Primary Electron Acceptor of Photosystem II: CD Determination of Its Coupling Environment, JOURNAL OF PHYSICAL CHEMISTRY B, Vol: 113, Pages: 12364-12374, ISSN: 1520-6106
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- Citations: 23
Rutherford AW, 2009, Biological and biomimetic water photolysis, 34th Congress of the Federation-of-European-Biochemical-Societies, Publisher: WILEY-BLACKWELL PUBLISHING, INC, Pages: 65-65, ISSN: 1742-464X
Boussac A, Sugiura M, Rutherford AW, et al., 2009, Complete EPR spectrum of the S3-state of the oxygen-evolving photosystem II., J Am Chem Soc, Vol: 131, Pages: 5050-5051
Despite crystallographic structures now available and intensive work in the past decades, little is known about the higher redox states of the catalytic cycle of Photosystem II, the enzyme responsible for the presence of O(2) on Earth and at the beginning of the process that has produced both the biomass and the fossil fuels. In one of the highest oxidation states, the S(3)-state, only signals at g-values higher than 4 have been detected so far at the X-band. In this work, we report for the first time the complete X-band EPR spectrum for the S(3)-state of Photosystem II. Simulations show that, for a spin state S = 1, as was previously suggested for S(3), it is not possible to account for all the features observed. A satisfactory simulated spectrum was obtained for a spin state S = 3 with zero-field splitting parameters D = 0.175 cm(-1) and E/D = 0.275. The detection of the full EPR signal for S(3) opens the door for new investigations and a better understanding of the catalytic cycle of Photosystem II.
Mackiewicz N, Delaire JA, Rutherford AW, et al., 2009, Carbon Nanotube-Acridine Nanohybrids: Spectroscopic Characterization of Photoinduced Electron Transfer, CHEMISTRY-A EUROPEAN JOURNAL, Vol: 15, Pages: 3882-3888, ISSN: 0947-6539
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- Citations: 11
Hughes JL, Rutherford AW, Sugiura M, et al., 2008, Quantum efficiency distributions of photo-induced side-pathway donor oxidation at cryogenic temperature in photosystem II, PHOTOSYNTHESIS RESEARCH, Vol: 98, Pages: 199-206, ISSN: 0166-8595
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- Citations: 9
Christoforidis KC, Louloudi M, Rutherford AW, et al., 2008, Semiquinone in molecularly imprinted hybrid amino acid-SiO<sub>2</sub> biomimetic materials.: An experimental and theoretical study, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 112, Pages: 12841-12852, ISSN: 1932-7447
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- Citations: 14
Rutherford AW, 2008, The water oxidizing enzyme, 15th European Bioenergetic Conference, Publisher: ELSEVIER SCIENCE BV, Pages: S3-S3, ISSN: 0005-2728
Jamin N, Rutherford AW, 2008, Jean-Michel Neumann - Obituary, TRENDS IN BIOCHEMICAL SCIENCES, Vol: 33, Pages: 297-297, ISSN: 0968-0004
Rutherford AW, Moore TA, 2008, Mimicking photosynthesis, but just the best bits, NATURE, Vol: 453, Pages: 449-449, ISSN: 0028-0836
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- Citations: 19
Ishida N, Sugiura M, Rappaport F, et al., 2008, Biosynthetic exchange of bromide for chloride and strontium for calcium in the photosystem II oxygen-evolving enzymes., J Biol Chem, Vol: 283, Pages: 13330-13340, ISSN: 0021-9258
The active site for water oxidation in photosystem II goes through five sequential oxidation states (S(0) to S(4)) before O(2) is evolved. It consists of a Mn(4)Ca cluster close to a redox-active tyrosine residue (Tyr(Z)). Cl(-) is also required for enzyme activity. To study the role of Ca(2+) and Cl(-) in PSII, these ions were biosynthetically substituted by Sr(2+) and Br(-), respectively, in the thermophilic cyanobacterium Thermosynechococcus elongatus. Irrespective of the combination of the non-native ions used (Ca/Br, Sr/Cl, Sr/Br), the enzyme could be isolated in a state that was fully intact but kinetically limited. The electron transfer steps affected by the exchanges were identified and then investigated by using time-resolved UV-visible absorption spectroscopy, time-resolved O(2) polarography, and thermoluminescence spectroscopy. The effect of the Ca(2+)/Sr(2+) and Cl(-)/Br(-) exchanges was additive, and the magnitude of the effect varied in the following order: Ca/Cl < Ca/Br < Sr/Cl < Sr/Br. In all cases, the rate of O(2) release was similar to that of the S(3)Tyr(Z)(.) to S(0)Tyr(Z) transition, with the slowest kinetics (i.e. the Sr/Br enzyme) being approximately 6-7 slower than in the native Ca/Cl enzyme. This slowdown in the kinetics was reflected in a decrease in the free energy level of the S(3) state as manifest by thermoluminescence. These observations indicate that Cl(-) is involved in the water oxidation mechanism. The possibility that Cl(-) is close to the active site is discussed in terms of recent structural models.
Batista V, Klimov VV, Rutherford AW, et al., 2008, Discussion, Philosophical Transactions of the Royal Society B: Biological Sciences, Vol: 363, Pages: 1245-1251, ISSN: 0962-8436
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- Citations: 1
Boussac A, Sugiura M, Lai T-L, et al., 2008, Low-temperature photochemistry in photosystem II from <i>Thermosynechococcus elongatus</i> induced by visible and near-infrared light, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 363, Pages: 1203-1210, ISSN: 0962-8436
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- Citations: 32
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