1. University of Cologne, Faculty of Mathematics and Natural Sciences, Department of Chemistry, Institute of Biochemistry, Zuelpicher Str. 47a, 50674 Cologne, Germany
2. Interdepartmental Research Unit of Peptide and Protein Chemistry and Biology, Department of Chemistry “Ugo Schiff”, University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy
3. University of Cologne, Faculty of Medicine, Institute for Clinical Chemistry, Kerpener Str. 62, 50937 Cologne, Germany
4. University of Cologne, Faculty of Mathematics and Natural Sciences, Department of Physics, Institute for Biological Physics, Zuelpicher Str. 47a, 50674 Cologne, Germany