Current position
Professor and Head of Photobioenergetics Group
Research interests
The photosynthetic production of oxygen by green plants is the primary source of the atmospheric oxygen and is essential for all aerobic life on earth. The process takes place in the highly specialized, chlorophyll/protein complex called photosystem II. In the generation of molecular O2, water is oxidized in a four-step reaction sequence at a unique manganese/calcium-containing site, providing the protons and electrons that are ultimately used in carbon assimilation.
In an associated research project we are also attempting to mimic various aspects of photosystem II structure and function through the molecular engineering of minimal model proteins (both natural and man-made), as part of a broader program in artificial photosynthesis and development of (Molecular Biofuels).
Some of the experimental approaches that we employ in our studies include:
- mass spectrometric measurements of rapid (ms time-range) oxygen isotope exchange reactions in photosystem II, used for determining the binding properties of the substrate water and mechanism of O-O bond formation;
- time-resolved, light-minus-dark difference Fourier transform infrared (FTIR) spectroscopy, used for investigating redox-active components, secondary protein structure and chemical bond formation and breakage in photosystem II reactions;
- electron paramagnetic resonance (EPR) spectroscopy, used for monitoring organic radicals and the catalytic manganese cluster.
In all of the above studies highly purified samples are prepared from higher plants, directed mutants of cyanobacteria, and E. coli over-expression strains using the latest techniques in molecular biology and biochemistry.
Selected Publications
Hillier W and Wydrzynski T (2008) 18O-water exchange in Photosystem II: substrate binding and intermediates of the water-splitting cycle. Coordination Chemistry Reviews 252, 306-317
Wydrzynski T, Hillier and Conlan B (2007) Engineering model proteins for Photosystem II function. Photosynthesis Research 94, 225-233
McConnell IL, Badger M, Wydrzynski T and Hillier W (2007) A quantitative assessment of the carbonic anhydrase activity in photosystem II. Biochimica et Biophysica Acta 1767, 639-647
Wydrzynski T and Satoh K, editors (2005) Photosystem II: The Light-Driven Water:Plastoquinone Oxidoreductase, In: Advances in Photosynthesis and Respiration, Vol 22 Springer, Dordrecht, pp. 1-786. [ISBN-10: 1-4020-4249-3]
Hay S, Wallace BB, Smith TA, Ghiggino KP and Wydrzynski T (2004) Protein engineering of cytochrome b562 for quinone binding and light-induced electron transfer. Proceedings of the National Academy of ScienceUSA 101, 17675-17680
Hillier W and Wydrzynski T (2004) Substrate water interactions within the photosystem II oxygen evolving complex. Physical Chemistry & Chemical Physics 6, 4882 -4889
Hendry G and Wydrzynski T (2003) 18O isotope exchange measurements reveal that calcium is involved in the binding of one substrate-water molecule to the oxygen-evolving complex in photosystem II. Biochemistry 42, 6209-6217
Razeghifard MR and Wydrzynski T (2003) Binding of Zn-Chlorin to a synthetic four-helix bundle peptide through histidine ligation. Biochemistry 42, 1024-1030
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