1. Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland, Functional Genomics Center Zürich (FGCZ), Winterthurerstrasse 190, CH-8057 Zürich, Switzerland, Dipartimento Farmaco-Chimico, Università di Bari, via E. Orabona 4, I-70125 Bari, Italy, School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, Scotland EH9 3JJ, UK, and Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 15, CZ-612 65 Brno, Czech Republic