1. BioTechnology Institute University of Minnesota 1479 Gortner Avenue Saint Paul MN 55108 USA
2. Present address: Department of Chemistry Bethel University 3900 Bethel Drive Saint Paul MN 55112 USA
3. Department of Medicinal Chemistry University of Minnesota 308 Harvard St. SE Minneapolis MN 55455 USA
4. Present address: UCB Biopharma Chemin du Foriest 1420 Braine-l'Alleud Belgium