1. Institute of Analytical and Pharmaceutical Chemistry The Royal Danish School of Pharmacy DK-2100 Copenhagen, Denmark Department of Chemistry, University of Copenhagen DK-2100 Copenhagen, Denmark Department of Biochemistry and Biophysics University of Göteborg and Chalmers Institute of Technology, S-412 96 Göteborg, Sweden Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel