1. Carlsberg Laboratory, Center for Solid-Phase Combinatorial Chemistry, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark, Carlsberg Biosector, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark, and Wellcome Trust Biocenter, School of Life Sciences, University of Dundee, Dow Street, DD1 5EH Dundee, U.K.