1. Department of Chemistry Ludwig-Maximilians-Universität München Butenandtstraße 5–13 81377 Munich Germany
2. Baseclick GmbH Floriansbogen 2–4 82061 Neuried (München Germany
3. Astbury Centre for Structural Molecular Biology School of Molecular and Cellular Biology, University of Leeds Leeds LS2 9JT UK
4. Department of Biochemistry University of Cambridge Cambridge CB2 1QW UK