1. Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, CambridgeCB2 1EW, U.K.
2. Department of Biochemistry & Structural Biology, Center for Molecular Protein Science, Lund University, 221 00Lund, Sweden
3. Department of Physics, Cavendish Laboratory, CambridgeCB3 0HE, U.K.