1. Department of Chemistry and Pharmacy, Emil-Fischer-Center, University of Erlangen−Nuremberg, Schuhstrasse 19, 91052 Erlangen, Germany, Institute of Molecular Systems Biology, Swiss Federal Institute of Technology Zurich, Wolfgang-Pauli-Strasse 16, 8093 Zurich, Switzerland, and Institute of Biochemistry, Emil-Fischer-Center, University of Erlangen−Nuremberg, Fahrstrasse 17, 91054 Erlangen, Germany