1. School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
2. Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
3. Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA
4. School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
5. Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
6. Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands