Professor
P. J. Hore
Physical & Theoretical Chemistry Laboratory
Telephone: 44 (0) 1865
275 415
Magnetic Resonance techniques
provide unparalleled atomic-level information on the structures,
motions and reactivity of molecules. Our work, which is experimental,
theoretical and computational, uses Nuclear Magnetic Resonance
(NMR), Electron Paramagnetic Resonance (EPR), and related methods
to study problems in biophysical chemistry.
Current projects
include studies of protein structure and folding, magnetoreception
in birds and plants, free radical chemistry and physics, and
the putative health hazards of non-ionizing electromagnetic
fields. Although at first sight disparate, these topics are
in fact linked by a class of transient reaction intermediates
known as radical pairs. Ubiquitous in photochemical, thermolytic
and radiolytic reactions, radical pairs have the defining characteristic
of a relatively long-lived electron spin-correlation, with
the consequence that their reaction rates and yields are modulated
by internal and external magnetic interactions that are orders
of magnitude weaker than the thermal energy per molecule, kBT.
Some of the questions we are trying to answer are summarized
below. More information can be found on the research
group web pages.
Real-time NMR of proteins
How does a protein achieve
its biologically active three-dimensional structure? An unbiased
search through the astronomical number of conformations available
to a polypeptide chain would result in folding on a geological
timescale. Most small proteins fold in seconds, some do so
in microseconds. We are developing new NMR techniques to follow
changes in the structures of proteins as they fold in real
time. This involves triggering the folding of a denatured protein
and using fast NMR techniques to monitor the subsequent structural
changes as the molecule rearranges to its native state.
Magnetoreception
Migratory birds travel vast distances each year, finding their
way by various means, including a remarkable ability to perceive
the Earth’s magnetic field. Although it has been known for
40 years that birds possess a magnetic compass, avian magnetoreception
remains poorly understood. We are exploring the idea that the
primary detector is a specialized ocular photoreceptor protein
(cryptochrome) that plays host to magnetically sensitive photochemical
reactions with radical pairs as fleeting intermediates.
Magnetokinetics
Chemists have long been fascinated by the possibility that
magnetic fields might influence the outcome of chemical reactions.
In recent years this has been brought into focus by concerns
about the harmful effects of power transmission lines, household
electrical equipment and mobile phones. We are trying to understand
how weak static and time-dependent magnetic interactions can
be used to probe and control the reactions of free radicals
that are too short-lived to be detectable by conventional EPR
methods.
Selected recent publications:
- 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.
- Oligomerization
of the human prion protein proceeds via a molten globule intermediate,
J. Biol. Chem., 282 (2007) 6300-6307.
- Bloch-Redfield-Wangsness
theory engine implementation using symbolic processing software,
J. Magn. Reson., 184 (2007) 196-206
- 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.
- 19F NMR studies of the native and denatured states of green
fluorescent protein, J. Amer. Chem. Soc. 128 (2006) 10729-10737.
- Multiple subsets of side-chain packing in partially folded
states of α-lactalbumins, Proc. Natl. Acad.
Sci. USA, 102 (2005)
8899-8904.
- Magnetic field effect on singlet oxygen production
in a biochemical system, Chem. Comm. 2005, 174-176.
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