1. Center for Solid-Phase Organic Combinatorial Chemistry, Department of Chemistry, Carlsberg Laboratory, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark, Division of Infection and Immunity, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, U.K., and Wellcome Centre for Molecular Parasitology, Anderson College, University of Glasgow, Glasgow G11 6NU, U.K.