1. Department of Biochemistry & Molecular BiologyIndiana University School of Medicine Indianapolis Indiana 46202 USA
2. ENSCO, Inc. 4849 North Wickham Road Melbourne Florida 32940 USA
3. 9 European Molecular Biology Laboratory 71 Avenue des Martyrs, CS 90181 38042 Grenoble, Cedex 9 France
4. Cardiff Catalysis InstituteSchool of ChemistryCardiff University Cardiff CF10 3AT UK