1. Department of Chemistry; Konstanz Research School-Chemical Biology; University of Konstanz; Universitätsstrasse 10 78457 Konstanz Germany
2. Department of Chemical Physiology; The Skaggs Institute for Chemical Biology; The Scripps Research Institute; 10550 North Torrey Pines Road La Jolla CA 92037 USA
3. Department of Biology; University of Konstanz; Universitätsstrasse 10 78457 Konstanz Germany