1. School of Molecular and Cell Biology and Astbury Centre, University of Leeds, Leeds LS2 9JT, U.K.
2. Department of Chemistry, University of California, Irvine, California 92697-3900, United States
3. Leiden University, Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, The Netherlands
4. Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, United States
5. Department of Pharmaceutical Sciences, University of California, Irvine, California 92697-3900, United States
6. School of Mathematics, University of Leeds, Leeds LS2 9JT, U.K.