1. School of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
2. Dynamic Structural Science Consortium, Research Complex at Harwell, Didcot OX11 0FA, U.K.
3. School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K.
4. Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K.