1. Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, Section of Biochemistry, University of Florence, 50134 Florence, Italy
2. Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge CB2 1EW, U.K.
3. Department of Physics, Cavendish Laboratory, 19 J. J. Thomson Avenue, Cambridge CB3 0HE, U.K.