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Effect of Ca(2+)/Sr...
Effect of Ca(2+)/Sr(2+) substitution on the electronic structure of the oxygen-evolving complex of photosystem II : a combined multifrequency EPR, (55)Mn-ENDOR, and DFT study of the S(2) State
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- Cox, Nicholas (author)
- Max Planck Inst Bioanorgan Chem, D-45470 Mulheim, Germany.
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- Rapatskiy, Leonid (author)
- Max Planck Inst Bioanorgan Chem, D-45470 Mulheim, Germany.
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- Su, Ji-Hu (author)
- Max Planck Inst Bioanorgan Chem, D-45470 Mulheim, Germany.
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- Pantazis, Dimitrios A (author)
- Max Planck Inst Bioanorgan Chem, D-45470 Mulheim, Germany.;Univ Bonn, Lehrstuhl Theoret Chem, Inst Phys & Theoret Chem, D-53115 Bonn, Germany.
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- Sugiura, Miwa (author)
- Ehime Univ, Cell Free Sci & Technol Res Ctr, Matsuyama, Ehime 7908577, Japan.
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- Kulik, Leonid (author)
- Inst Chem Kinet & Combust, Novosibirsk 630090, Russia.
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- Dorlet, Pierre (author)
- CEA Saclay, iBiTec S, URA CNRS 2096, F-91191 Gif Sur Yvette, France.
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- Rutherford, A William (author)
- CEA Saclay, iBiTec S, URA CNRS 2096, F-91191 Gif Sur Yvette, France.
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- Neese, Frank (author)
- Max Planck Inst Bioanorgan Chem, D-45470 Mulheim, Germany.;Univ Bonn, Lehrstuhl Theoret Chem, Inst Phys & Theoret Chem, D-53115 Bonn, Germany.
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- Boussac, Alain (author)
- CEA Saclay, iBiTec S, URA CNRS 2096, F-91191 Gif Sur Yvette, France.
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- Lubitz, Wolfgang (author)
- Max Planck Inst Bioanorgan Chem, D-45470 Mulheim, Germany.
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- Messinger, Johannes (author)
- Umeå universitet,Kemiska institutionen,Umea Univ, Dept Chem, Chem Biol Ctr KBC, S-90187 Umea, Sweden.
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Max Planck Inst Bioanorgan Chem, D-45470 Mulheim, Germany Max Planck Inst Bioanorgan Chem, D-45470 Mulheim, Germany.;Univ Bonn, Lehrstuhl Theoret Chem, Inst Phys & Theoret Chem, D-53115 Bonn, Germany. (creator_code:org_t)
- 2011-02-22
- 2011
- English.
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 133:10, s. 3635-3648
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https://doi.org/10.1...
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Abstract
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- The electronic structures of the native Mn(4)O(x)Ca cluster and the biosynthetically substituted Mn(4)O(x)Sr cluster of the oxygen evolving complex (OEC) of photosystem II (PSII) core complexes isolated from Thermosynechococcus elongatus, poised in the S(2) state, were studied by X- and Q-band CW-EPR and by pulsed Q-band (55)Mn-ENDOR spectroscopy. Both wild type and tyrosine D less mutants grown photoautotrophically in either CaCl(2) or SrCl(2) containing media were measured. The obtained CW-EPR spectra of the S(2) state displayed the characteristic, clearly noticeable differences in the hyperfine pattern of the multiline EPR signal [Boussac et al. J. Biol. Chem.2004, 279, 22809-22819]. In sharp contrast, the manganese ((55)Mn) ENDOR spectra of the Ca and Sr forms of the OEC were remarkably similar. Multifrequency simulations of the X- and Q-band CW-EPR and (55)Mn-pulsed ENDOR spectra using the Spin Hamiltonian formalism were performed to investigate this surprising result. It is shown that (i) all four manganese ions contribute to the (55)Mn-ENDOR spectra; (ii) only small changes are seen in the fitted isotropic hyperfine values for the Ca(2+) and Sr(2+) containing OEC, suggesting that there is no change in the overall spin distribution (electronic coupling scheme) upon Ca(2+)/Sr(2+) substitution; (iii) the changes in the CW-EPR hyperfine pattern can be explained by a small decrease in the anisotropy of at least two hyperfine tensors. It is proposed that modifications at the Ca(2+) site may modulate the fine structure tensor of the Mn(III) ion. DFT calculations support the above conclusions. Our data analysis also provides strong support for the notion that in the S(2) state the coordination of the Mn(III) ion is square-pyramidal (5-coordinate) or octahedral (6-coordinate) with tetragonal elongation. In addition, it is shown that only one of the currently published OEC models, the Siegbahn structure [Siegbahn, P. E. M. Acc. Chem. Res.2009, 42, 1871-1880, Pantazis, D. A. et al. Phys. Chem. Chem. Phys.2009, 11, 6788-6798], is consistent with all data presented here. These results provide important information for the structure of the OEC and the water-splitting mechanism. In particular, the 5-coordinate Mn(III) is a potential site for substrate 'water' (H(2)O, OH(-)) binding. Its location within the cuboidal structural unit, as opposed to the external 'dangler' position, may have important consequences for the mechanism of O-O bond formation.
Subject headings
- NATURVETENSKAP -- Kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences (hsv//eng)
- NATURVETENSKAP -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)
Keyword
- Chemistry
- Kemi
Publication and Content Type
- ref (subject category)
- art (subject category)
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- By the author/editor
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Cox, Nicholas
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Rapatskiy, Leoni ...
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Su, Ji-Hu
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Pantazis, Dimitr ...
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Sugiura, Miwa
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Kulik, Leonid
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Dorlet, Pierre
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Rutherford, A Wi ...
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Neese, Frank
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Boussac, Alain
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Lubitz, Wolfgang
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Messinger, Johan ...
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- About the subject
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Chemical Science ...
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Biological Scien ...
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and Biochemistry and ...
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Umeå University
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Uppsala University