1. Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
2. Department of Chemistry, Ludwig Maximilians University Munich, Munich, Germany
3. Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
4. Department of Chemistry, New York University, New York, United States
5. The Vollum Institute, Oregon Health and Science University, Portland, United States