NATURAL and ARTIFICIAL PHOTOSYNTHESIS GROUP Dr. Ron J. Pace Reader, Bio-Physical Chemistry Department of Chemistry, Faculty of Science, ANU 0200 Canberra ACT AUSTRAIA Email: Ron.Pace@anu.edu.au Phone: +61-(0)2-61254546 Fax : +61-(0)2-61258997

Reseach Interests

PHOTOSYNTHESIS:

Research in this area involves ARC funded collaborations with other groups at ANU, in the Chemistry Department, Research School of Chemistry and Research School of Biological Sciences.

Natural Photosynthesis : The work focuses on the primary light capture and electron transfer processes in Photosystem II (PS II). This protein complex, found in plants and photosynthetic bacteria, generates molecular oxygen by photo-catalytic oxidation of water and supports most animal life on earth. The water splitting reaction occurs within a unique, Mn4- Ca active site of PS II, whose detailed molecular structure and mechanism present great challenges for chemical understanding. The centre executes the most energetically demanding reaction in nature by means not yet understood.

Our group has developed ultra-high purity preparations of photosystem II material from plants, which are a unique experimental resource[1] We employ a broad range of spectroscopic tools to study catalytic processes in PS II. These include: Fourier transform infrared spectroscopy (FTIR), CW and Pulsed EPR and magneto-optical spectroscopy (with E. Krausz ,RSC) [2].

An active theoretical program operates within the group. This involves simulation studies of the spectral signatures of paramagnetic intermediates within the water oxidising catalytic cycle, to explore the mechanism, and high level quantum computational studies (with R. Stranger, Chemistry) of Mn cluster geometries and oxidation states.

Artificial Photosynthesis: We have a broad interest in all aspects of artificial photosynthesis (eg see [3]), but work is currently directed towards development of bio-mimetic catalysts for electrolytic H2 production. The Mn4- Ca cluster in PS II is by far the most efficient anodic water oxidising system known. Its mechanism holds the key to cost competitive and totally renewable generation of H2 fuel from water. This work involves collaboration with groups at Uppsala University, Sweden.

MEMBRANE BIOSENSORS:

A novel, ultra-high sensitivity biosensor system, based on synthetic ion channels has been developed in collaboration with the CRC for Molecular Sensing Technologies (Sydney) [4] Aspects of the supported membrane technology employed in this work will be required for full implementation of the artificial photosynthesis program outlined in the above figure.

Selected Publications

[1] 'Magneto-Optical Measurements of the Pigments in Fully Active Photosystem II Complexes from Plants'
P.J. Smith, S. Peterson, V. Masters, T. Wydrzynski, S. Styring , E. Krausz and R. J. Pace Biochemistry 41,1981-1989 (2002)

[2] 'Optical Spectra of Synechocyctis and Spinach Photosystem II Preparations at 1.7 K: Identification of the D1- Pheophytin Energies and Stark Shifts'S. Peterson, V. Masters, B. J. Prince, P.J. Smith, R. J. Pace and E. Krausz (2003) 'J. Am. Chem. Soc. 125, 13063-13074

[3] R.J. Pace, ' An Integrated Artificial Photosynthesis Model' in 'Artificial Photosynthesis', A. Collings, C Critchley eds. Wiley-VCH, 2005, Chap. 2

[4] 'A Biosensor that uses Ion-Channel Switches'
B.A. Cornell, V.L.B. Brach-Maksvytis, L.G. King, P.D.J. Osman, B. Raguse, L. Wieczorek and R.J. Pace , Nature, 387, 580-583 (1997).