Research Guides

My group studies radical pairs – ubiquitous short-lived reaction intermediates whose chemistry is controlled to a large extent by electron and nuclear spins. Their defining characteristics are spin-selective reactivity and long-lived spin-coherences which result in reaction rates and product yields that are sensitive to magnetic interactions orders of magnitude weaker than the thermal energy per molecule, kT. Thus, manifestly quantum effects of weak magnetic fields on chemical reactions occur under conditions where the corresponding classical effects would be entirely negligible.

Our research exploits the unique properties of radical pairs using a range of experimental and theoretical approaches.  For example:

• We are testing the hypothesis that birds rely on radical pair reactions in the retina to detect the direction of the Earth’s magnetic field as a compass for use during migration.

• We develop and apply NMR techniques for studying protein folding in real time using the nuclear spin polarization effects that arise in photo-induced radical pair reactions.

• We aim to determine whether exposure to environmental electromagnetic fields (from power transmission lines, household electrical equipment, mobile phones, etc.) can influence biological radical pair reactions and hence have implications for human health.

• We use weak static and time-dependent magnetic interactions to probe and control the reactions of radical pairs that are too short-lived to be detectable by more conventional magnetic resonance methods.

• We are applying ideas from quantum measurement theory to find the correct way to describe spin-selective radical pair reactivity.

• We have developed and are using a variety of approaches to accelerate Liouville-space simulations of the large densely coupled spin systems encountered in EPR spectroscopy and Spin Chemistry.

More information can be found on our research group web pages.
 
Current funding is provided by EPSRC, the EMF Biological Research Trust (a UK medical charity) and the US government agency DARPA.

Current collaborators include:  Christiane Timmel (ICL, Oxford), Stuart Mackenzie (PTCL, Oxford), Mark Wallace (PTCL, Oxford), Devens Gust (Arizona State University), Henrik Mouritsen (University of Oldenburg), Christoph Lienau (University of Oldenburg), Stefan Weber (University of Freiburg).
 

• Strategies for state space restriction in densely coupled spin systems with applications to spin chemistry, J. Chem. Phys., 132 (2010) 174101

• Spin-selective reactions of radical pairs act as quantum measurements, Chem. Phys. Lett., 488 (2010) 90–93

• Magnetic compass of birds is based on a molecule with optimal directional sensitivity, Biophys. J., 96 (2009) 3451-3457

• Effect of magnetic fields on cryptochrome-dependent responses in Arabidopsis thaliana, J. Roy. Soc. Interface, 6 (2009) 1193-1205

• Chemical magnetoreception in birds: the radical pair mechanism, Proc. Natl. Acad. Sci. USA, 106 (2009) 353-360

• Magnetic field effect on the photoactivation reaction of Escherichia coli DNA photolyase, Proc. Natl. Acad. Sci. USA, 105 (2008) 14395-14399

• Chemical compass model of avian magnetoreception, Nature, 453 (2008) 387-390

• Determination of radical re-encounter probability distributions from magnetic field effects on reaction yields, J. Amer. Chem. Soc., 129 (2007) 6746-6755

• A pre-existing hydrophobic collapse in the unfolded state of an ultrafast folding protein, Nature, 447 (2007) 106-109

• Oligomerization of the human prion protein proceeds via a molten globule intermediate, J. Biol. Chem., 282 (2007) 6300-6307

• ¹⁹F NMR studies of the native and denatured states of green fluorescent protein, J. Amer. Chem. Soc. 128 (2006) 10729-10737

• Analysis of the spin-polarized electron spin echo of the [P₇₀₀⁺A₁^-] radical pair of photosystem I indicates that both reaction centre subunits are competent in electron transfer in cyanobacteria, green algae, and higher plants, Biochemistry, 45 (2006) 7389-7403

• Multiple subsets of side-chain packing in partially folded states of alpha-lactalbumins, Proc. Natl. Acad. Sci. USA, 102 (2005) 8899-8904

 A complete list of publications can be found here.