1. Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
2. Department of Chemistry, Johannes Gutenberg-University, 55099 Mainz, Germany
3. Katz Group Center, University of Alberta, Edmonton, AB T6G 2T9, Canada
4. Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz, Germany