1. Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200f−bus 02404, 3001 Heverlee, Leuven, Belgium, Institut Curie, Service Bioinformatique, 26 Rue d'Ulm, Paris Cedex 05, 75248 France, and Biomedical Research Institute, Hasselt University and Transnationale Universiteit Limburg, Agoralaan, Building D, 3590 Diepenbeek, Belgium