1. Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, D-97070 Würzburg, Germany
2. Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Würzburg, Würzburg, Germany
3. Institute for Chemical Biology and Drug Discovery, Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States