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Science 11 November 2005:
Vol. 310. no. 5750, pp. 1019 - 1021
DOI: 10.1126/science.1117551
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Reports

Photosynthetic O2 Formation Tracked by Time-Resolved X-ray Experiments

M. Haumann,* P. Liebisch, C. Müller, M. Barra, M. Grabolle, H. Dau*

Plants and cyanobacteria produce atmospheric dioxygen from water, powered by sunlight and catalyzed by a manganese complex in photosystem II. A classic S-cycle model for oxygen evolution involves five states, but only four have been identified. The missing S4 state is particularly important because it is directly involved in dioxygen formation. Now progress comes from an x-ray technique that can monitor redox and structural changes in metal centers in real time with 10-microsecond resolution. We show that in the O2-formation step, an intermediate is formed—the enigmatic S4 state. Its creation is identified with a deprotonation process rather than the expected electron-transfer mechanism. Subsequent electron transfer would give an additional S4' state, thus extending the fundamental S-state cycle of dioxygen formation.

Freie Universität Berlin, FB Physik, Arnimallee 14, D-14195 Berlin, Germany

* To whom correspondence should be addressed. E-mail: haumann{at}physik.fu-berlin.de (M.H.); holger.dau{at}physik.fu-berlin.de (H.D.)

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Biosynthetic Exchange of Bromide for Chloride and Strontium for Calcium in the Photosystem II Oxygen-evolving Enzymes.
N. Ishida, M. Sugiura, F. Rappaport, T.-L. Lai, A. W. Rutherford, and A. Boussac (2008)
J. Biol. Chem. 283, 13330-13340
   Abstract »    Full Text »    PDF »
Evidence for Intermediate S-States as Initial Phase in the Process of Oxygen-Evolving Complex Oxidation.
J. Jablonsky and D. Lazar (2008)
Biophys. J. 94, 2725-2736
   Abstract »    Full Text »    PDF »
Enthalpy Changes during Photosynthetic Water Oxidation Tracked by Time-Resolved Calorimetry Using a Photothermal Beam Deflection Technique.
R. Krivanek, H. Dau, and M. Haumann (2008)
Biophys. J. 94, 1890-1903
   Abstract »    Full Text »    PDF »
Deletion of PsbM in Tobacco Alters the QB Site Properties and the Electron Flow within Photosystem II.
P. Umate, S. Schwenkert, I. Karbat, C. D. Bosco, L. Mlcochova, S. Volz, H. Zer, R. G. Herrmann, I. Ohad, and J. Meurer (2007)
J. Biol. Chem. 282, 9758-9767
   Abstract »    Full Text »    PDF »
PsbI Affects the Stability, Function, and Phosphorylation Patterns of Photosystem II Assemblies in Tobacco.
S. Schwenkert, P. Umate, C. D. Bosco, S. Volz, L. Mlcochova, M. Zoryan, L. A. Eichacker, I. Ohad, R. G. Herrmann, and J. Meurer (2006)
J. Biol. Chem. 281, 34227-34238
   Abstract »    Full Text »    PDF »
Calcium Exchange and Structural Changes during the Photosynthetic Oxygen Evolving Cycle.
A. De Riso, D. L. Jenson, and B. A. Barry (2006)
Biophys. J. 91, 1999-2008
   Abstract »    Full Text »    PDF »
Time-resolved vibrational spectroscopy detects protein-based intermediates in the photosynthetic oxygen-evolving cycle.
B. A. Barry, I. B. Cooper, A. De Riso, S. H. Brewer, D. M. Vu, and R. B. Dyer (2006)
PNAS 103, 7288-7291
   Abstract »    Full Text »    PDF »
A time-resolved vibrational spectroscopy glimpse into the oxygen-evolving complex of photosynthesis.
T. M. Bricker (2006)
PNAS 103, 7205-7206
   Full Text »    PDF »


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Science. ISSN 0036-8075 (print), 1095-9203 (online)