1. Department of Molecular Microbiology Groningen Institute for Biomolecular Sciences and Biotechnology University of Groningen 9747 AG Groningen The Netherlands
2. Department of Pharmaceutical Technology and Biopharmacy Groningen Research Institute of Pharmacy University of Groningen 9713AV Groningen The Netherlands
3. Chair of Medicinal and Bioinorganic Chemistry Department of Chemistry Technical University of Munich Lichtenbergstr. 4 85748 Garching b. München Germany