1. Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, Department of Medicine, Cardiovascular Division, and Department of Pharmacology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104, Laboratorium voor Medicinale Chemie (FFW), Harelbekestraat 72, B-9000 Gent, Belgium, and Institut für Pharmazie, Fachbereich Chemie, Universität Hamburg,...