1. Departments of Chemistry, University of Bath, Bath BA2 7AX, U.K.
2. Department of Biochemistry, King’s College London, London WC2R 2LS, U.K.
3. BHF Centre of Research Excellence, School of Medicine and Life Sciences, King’s College London, London WC2R 2LS, U.K.
4. Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K.