1. Center for Biomolecular Recognition, Department of Medical Biochemistry and Genetics, Laboratory B, The Panum Institute Blegdamsvej 3c DK‐2200 Copenhagen N Denmark
2. Department of Molecular Biophysics and Biochemistry, Yale University, PO Box 208114 266 Whitney Avenue New Haven CT 06520‐8114 USA
3. Department of Chemistry, Yale University New Haven CT 06520‐8114 USA
4. Molecular, Cellular and Developmental Biology, Yale University New Haven CT 06520‐8114 USA