1. Department of Chemistry, The H.C. Ørsted Institute, University of Copenhagen, DK-2100 København Ø, Denmark
2. Laboratoire de Biochimie et de Biologie Moléculaire, IFR 6, CR. C. Bernard, Hôpital Lariboisière, 2 rue Ambroise Paré, 75475 Paris Cedex 10, France
3. Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2