1. Department of Chemistry, Building 207, Technical University of Denmark, DK-2800, Lyngby, Denmark; Department of Pharmaceutics, The Royal Danish School of Pharmacy, Universitetsparken 2, DK-2100 Copenhagen Ø, Denmark; Department of Biochemistry and the Graduate Program in Biophysics, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908; and Department of Pharmacology, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908