Water oxidation energy diagrams for photosystem II for different protonation states, and the effect of removing calcium.

The main parts of the water oxidation mechanism in photosystem II have now been established both from theory and experiments. Still, there are minor questions remaining. One of them concerns the charge and the protonation state of the oxygen evolving complex (OEC). Previously, theory and experiments have agreed that the two water derived ligands on the outer manganese should be one hydroxide and one water. In the present study it is investigated whether both of them could be water. This question is addressed by a detailed study of energy diagrams, but in this context it is more conclusive to compare the redox potential of the OEC to the one of TyrZ. Both procedures lead to the conclusion that one of the ligands is a hydroxide. Another question concerns the protonation of the second shell His337, where the results are more ambiguous. The final part of the present study describes results when calcium is removed from the OEC. Even though protons enter to compensate the charge of the missing Ca(2+), the redox potential and the pKa value of the OEC change dramatically and prevent the progress after S2.

[1]  M. Blomberg,et al.  Energy Diagrams for Water Oxidation in Photosystem II Using Different Density Functionals. , 2014, Journal of chemical theory and computation.

[2]  Emily Y. Tsui,et al.  Synthetic cluster models of biological and heterogeneous manganese catalysts for O2 evolution. , 2013, Inorganic chemistry.

[3]  V. Batista,et al.  S0-State model of the oxygen-evolving complex of photosystem II. , 2013, Biochemistry.

[4]  P. Siegbahn.  Water oxidation mechanism in photosystem II, including oxidations, proton release pathways, O-O bond formation and O2 release. , 2013, Biochimica et biophysica acta.

[5]  U. Bergmann,et al.  Electronic structural changes of Mn in the oxygen-evolving complex of photosystem II during the catalytic cycle. , 2013, Inorganic chemistry.

[6]  F. Neese,et al.  Detection of the water-binding sites of the oxygen-evolving complex of Photosystem II using W-band 17O electron-electron double resonance-detected NMR spectroscopy. , 2012, Journal of the American Chemical Society.

[7]  M. Haumann,et al.  Alternating electron and proton transfer steps in photosynthetic water oxidation , 2012, Proceedings of the National Academy of Sciences.

[8]  W. Lubitz,et al.  The Basic Properties of the Electronic Structure of the Oxygen-evolving Complex of Photosystem II Are Not Perturbed by Ca2+ Removal* , 2012, The Journal of Biological Chemistry.

[9]  P. Siegbahn.  Mechanisms for proton release during water oxidation in the S2 to S3 and S3 to S4 transitions in photosystem II. , 2012, Physical chemistry chemical physics : PCCP.

[10]  Olivier Jacquet,et al.  Cover Picture: A Diagonal Approach to Chemical Recycling of Carbon Dioxide: Organocatalytic Transformation for the Reductive Functionalization of CO2 (Angew. Chem. Int. Ed. 1/2012) , 2012 .

[11]  D. Pantazis,et al.  Theoretical evaluation of structural models of the S2 state in the oxygen evolving complex of Photosystem II: protonation states and magnetic interactions. , 2011, Journal of the American Chemical Society.

[12]  F. Rappaport,et al.  Ca2+ determines the entropy changes associated with the formation of transition states during water oxidation by Photosystem II , 2011 .

[13]  J. Yano,et al.  Calcium in the oxygen-evolving complex: structural and mechanistic role determined by X-ray spectroscopy. , 2011, Journal of photochemistry and photobiology. B, Biology.

[14]  Keisuke Kawakami,et al.  Crystal structure of oxygen-evolving photosystem II at a resolution of 1.9 Å , 2011, Nature.

[15]  W. Junge,et al.  Membrane-inlet mass spectrometry reveals a high driving force for oxygen production by photosystem II , 2011, Proceedings of the National Academy of Sciences.

[16]  P. Siegbahn.  Structures and energetics for O2 formation in photosystem II. , 2009, Accounts of chemical research.

[17]  P. Siegbahn.  A structure-consistent mechanism for dioxygen formation in photosystem II. , 2008, Chemistry.

[18]  S. Grimme,et al.  Double-hybrid density functionals with long-range dispersion corrections: higher accuracy and extended applicability. , 2007, Physical chemistry chemical physics : PCCP.

[19]  P. Siegbahn.  O-O bond formation in the S(4) state of the oxygen-evolving complex in photosystem II. , 2006, Chemistry.

[20]  G. Brudvig,et al.  Water-splitting chemistry of photosystem II. , 2006, Chemical reviews.

[21]  Jan Kern,et al.  Towards complete cofactor arrangement in the 3.0 Å resolution structure of photosystem II , 2005, Nature.

[22]  M. Grabolle,et al.  Photosynthetic O2 Formation Tracked by Time-Resolved X-ray Experiments , 2005, Science.

[23]  J. Messinger.  Evaluation of different mechanistic proposals for water oxidation in photosynthesis on the basis of Mn4OxCa structures for the catalytic site and spectroscopic data , 2004 .

[24]  B. Sjöberg,et al.  Structural and mutational studies of the carboxylate cluster in iron-free ribonucleotide reductase R2. , 2004, Biochemistry.

[25]  James Barber,et al.  Architecture of the Photosynthetic Oxygen-Evolving Center , 2004, Science.

[26]  Per E M Siegbahn,et al.  Mechanisms of metalloenzymes studied by quantum chemical methods , 2003, Quarterly Reviews of Biophysics.

[27]  M. Reiher,et al.  Reparameterization of hybrid functionals based on energy differences of states of different multiplicity , 2001 .

[28]  J. Lavergne,et al.  Coupling of electron and proton transfer in the photosynthetic water oxidase. , 2001, Biochimica et biophysica acta.

[29]  B. Diner.  Amino acid residues involved in the coordination and assembly of the manganese cluster of photosystem II. Proton-coupled electron transport of the redox-active tyrosines and its relationship to water oxidation. , 2001, Biochimica et biophysica acta.

[30]  V. DeRose,et al.  Structural Effects of Calcium Depletion on the Manganese Cluster of Photosystem II: Determination by X-ray Absorption Spectroscopy. , 1998, The journal of physical chemistry. B.

[31]  G. Renger.  Mechanistic and structural aspects of photosynthetic water oxidation , 1997 .

[32]  Robert H. Crabtree,et al.  Mechanism of C−H Activation by Diiron Methane Monooxygenases: Quantum Chemical Studies , 1997 .

[33]  A. Rutherford,et al.  Conversion of the spin state of the manganese complex in photosystem II induced by near-infrared light. , 1996, Biochemistry.

[34]  A. Becke.  Density-functional thermochemistry. III. The role of exact exchange , 1993 .

[35]  A. Rutherford,et al.  Nature of the inhibition of the oxygen-evolving enzyme of photosystem II induced by sodium chloride washing and reversed by the addition of calcium(2+) or strontium(2+) , 1988 .

[36]  W. Junge,et al.  STOICHIOMETRY and KINETICS OF PROTON RELEASE UPON PHOTOSYNTHETIC WATER OXIDATION , 1985 .

[37]  G. Dismukes,et al.  Intermediates of a polynuclear manganese center involved in photosynthetic oxidation of water. , 1981, Proceedings of the National Academy of Sciences of the United States of America.