1. School of Biomedical Sciences, and The Astbury Centre for Structural Molecular Biology; University of Leeds; Leeds LS2 9JT U.K
2. Department of Chemistry; University of Cambridge; Lensfield Road Cambridge CB2 1EW U.K.
3. Advanced Institute for Materials Research; Tohoku University; 2-1-1 Katahira Aoba-ku Sendai Miyagi 980-8577 Japan
4. Centre for Molecular and Structural Biochemistry; School of Chemistry, and School of Biological Sciences; University of East Anglia; Norwich Research Park Norwich NR4 7TJ United Kingdom