1. Department of Chemistry, New York University, New York, New York 10003, United States
2. Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
3. Department of Biochemistry, University of Geneva, Geneva, Switzerland
4. National Centre of Competence in Research (NCCR) in Chemical Biology, University of Geneva, Geneva, Switzerland
5. Department of Chemistry, University of Buffalo, The State University of New York (SUNY), Buffalo, New York, United States
6. Department of Chemistry and Center for Integrated Protein Science, Ludwig Maximilians University Munich, 81377 Munich, Germany