Events at the University of Science and Technology of China

Water Splitting in Photosynthesis Studied by Magnetic Resonance Techniques

  • [2017-10-20]

    Speaker: Prof. Wolfgang Lubitz
    Max-Planck-Institut für Chemische Energiekonversion, Mülheim/Ruhr, Germany
    Time: 2017-10-20 10:00
    Place: Exhibition Hall, Hefei National Laboratory Building


      The invention of water splitting and oxygen release by early photosynthetic organisms was the cornerstone for the development of our planet´s oxygen-rich atmosphere and the protective ozone layer in the stratosphere, which was essential for the development of higher life on earth. Photosynthesis stores the sun´s energy via CO2 reduction in form of energy-rich organic compounds. It is the only basic source of food and other biomaterials on earth and has created all our fossil fuels.
      The catalytic water oxidation reaction is performed by a protein-bound Mn4OxCa cluster located in the so-called photosystem II (PSII) [1]. The cofactor´s reaction cycle is comprised of 5 distinct redox intermediates Sn, where the subscript indicates the number of stored oxidizing equivalents in the Mn cluster (n = 0 to 4) required to split two water molecules and release one O2. A redox-active tyrosine residue couples the fast light-induced single-electron charge separation to the slow catalytic four-electron water oxidation process. Almost all these states are paramagnetic; thus electron paramagnetic resonance is the method of choice to study the catalytic cycle and better understand this important biological process. The S-states are trapped by laser flash/freeze quench methods and their electronic structure is studied by advanced EPR techniques (ENDOR, ESEEM, ELDOR-detected NMR) [2,3]. The experimental data are corroborated by DFT calculations. The results give information on the electronic structure (spin and oxidation states) of the manganese ions [4], the function of the Ca2+ [5], the effect of the amino acid surrounding as well as the binding, location and reaction dynamics of the substrate water [6], the O-O bond formation and the release of molecular oxygen [7]. A robust model for the water oxidation mechanism is derived. This information can be used for the design of bioinspired catalysts for water oxidation [8,9].

    [1] (a) Umena, Y., et al. (2011) Nature, 473, 55; (b) Suga, M., et al. (2015) Nature, 517, 99.
    [2] Cox, N., Pantazis, D. A., Neese, F., Lubitz, W. (2013) Acc. Chem. Res., 46, 1588
    [3] Cox, N., Retegan, M., Neese, F., Pantazis, D. A., Boussac, A., Lubitz, W. (2014) Science, 345, 804.
    [4] (a) Kulik, L. V., et al. (2007) J. Am. Chem. Soc., 129, 13421; (b) Krewald, V., et al.. (2015) Chem. Sci., 6, 1676; (c) Retegan, M., et al. (2016) Chem. Sci., 7, 72.
    [5] (a) Lohmiller, T., et al. (2012) J. Biol. Chem., 287, 24721; (b) Cox, N., et al. (2011) J. Am. Chem. Soc., 133, 3635.
    [6] Rapatskiy, L., et al. (2012) J. Am. Chem. Soc., 134, 16619.
    [7] (a) Krewald, V., et al., N. (2016) Inorg. Chem., 55, 488; (b) Pérez-Navarro, M., et al. (2016) Curr. Opin. Chem. Biol., 31, 113.
    [8] Cox, N., Pantazis, D. A., Neese, F., Lubitz, W. (2015). Interface Focus, 5, 20150009
    [9] Lubitz, W., Lohmiller, T. and Cox, N. (2016) Bunsen-Magazin, 18. Jahrgang, Vol. 6, 216-223

    Organizer: Hefei National Laboratory for Physical Sciences at the Microscale



Highlight of USTC

According to the latest Nature Publishing Index (NPI) Asia-Pacific and The Nature Publishing Index China, University of Science and Technology of China tops in Chinese universities again. The rankings are based on the number of papers that were published in Nature journals during the last 12 months.


This article came from News Center of USTC.