1. Institute of Inorganic Chemistry II University Ulm Albert-Einstein-Allee 11 89081 Ulm Germany
2. Institute of Molecular Virology Ulm University Medical Center Meyerhofstrasse 1 89081 Ulm Germany
3. Department for Synthesis of Macromolecules Max-Planck-Institute for Polymer Research Ackermannweg 10 55128 Mainz Germany