1. Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
2. Institute of Biological Chemistry, Faculty of Chemistry, University of Vienna, Währinger Street 38, 1090 Vienna, Austria
3. Instituto de Medicina Molecular, Faculdade de Medicina de Universidad de Lisboa, 1649-028 Lisboa, Portugal
4. Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom