Godfrey Beddard

Research section: Physical Chemistry

KEYWORDS Femtosecond Laser Spectroscopy Light Triggered Protein Folding Electron Transfer Ultra-fast Reactions in Solution Dynamic Force Spectrometry

RESEARCH INTERESTS

Electron Transfer in DNA. Femtosecond laser spectroscopy allows us to follow several types of events such as electron transfer, bond breaking or isomerisation. Recent and ongoing experiments on dye - DNA complexes have allowed us to model electron transfer to the dye from the base pairs in DNA and so begin to understand how electrons and holes are transported along DNA prior to stand breaking.

Protein Folding. The molecular details of how proteins fold from the linear amino acid sequence to their unique three-dimensional structures is one of the major challenges in Chemical Physics. Although it has been known for more than twenty years that proteins can spontaneously fold to their native structures, how this is achieved is still not understood in any great detail. It is now known that misfolding is responsible for several diseases. Proteins are modified to be mis-folded by making new links between otherwise remote amino acids with disulphide bonds. These bonds are cleaved with a ultra-violet photon and the time course of subsequent folding followed by infra-red and visible laser spectroscopy.

Electronic Energy Migration. Specially designed small peptides will self-assemble into long ribbons. As each peptide contains a chromophore, either intrinsic or added by chemical modification we can, by using picosecond, time-resolved, single photon counting, follow energy migration along the ribbon. These ribbons mimic the light-harvesting antenna of photosynthetic organisms. By attaching electron acceptors and donors we are attempting to design artificial reaction centres.

Mechanical unfolding of proteins. An atomic force microscope is used to mechanically unfold single proteins and protein concatamers. The measured force at which the protein unfolds vs. distance over which the protein is extended is compared with theoretical predictions and tells us about the nature of the transition state for unfolding. Our current work is based around an I27 concatamer from the muscle protein Titin and we have recently shown that the transition state for chemical unfolding and forced unfolding is different. This is a collaborative project with colleagues in Physics and Biochemistry.

SELECTED PUBLICATIONS

Femtosecond Electron-Transfer Reactions in Mono- and Polynucleotides and in DNA. G. Reid, D. Whittaker, M. Day, D. Turton, V.Kayser, J. Kelly and G. Beddard, J. Am. Chem. Soc. (2002), 124, 5518

Pulling geometry defines the mechanical resistance of a b-sheet protein, D. J. Brockwell, E. Paci, R. C. Zinober, G. S. Beddard, P.Olmsted, D. A. Smith, R. N. Perham and S. E. Radford. Nature Structural Biology (2003), 10, 731

Energy Migration in Novel pH-Triggered Self-Assembled beta-Sheet Ribbons. V. Kayser, Veysel, D. Turton, A. Aggeli, A. Beevers, G. Reid, G. Beddard, Godfrey. Journal of the American Chemical Society (2004), 126(1), 336-343.

Mechanically unfolding the small, topologically simple protein L. D. Brockwell, G. Beddard, E. Paci, D. West, P. Olmsted, D. Smith & S. Radford, Biophysical Journal (2005), 89, 506