1. Department of Pharmacology, University of Minnesota Medical School—Twin Cities, Minneapolis, Minnesota 55455
2. Department of Biochemistry, Molecular Biology, and Biophysics and Biotechnology Institute, University of Minnesota, St. Paul, Minnesota 55108
3. Department of Medicinal Chemistry and Institute for Therapeutic Discovery and Development, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55414
4. Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298
5. Mikrobiologisches Institut, Universität Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany