1. Department
of Biology, University of Copenhagen, Copenhagen, Denmark
2. SISSA-Scuola Internazionale Superiore di Studi Avanzati, Trieste, Italy
3. Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
4. Laboratory
of Chemical Physics, National Institute of Diabetes and Digestive
and Kidney Diseases, National Institutes of Health, 9000 Rockville
Pike, Bethesda, Maryland, United States