1. Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States
2. Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
3. Carle Illinois College of Medicine, University of Illinois, Urbana, Illinois 61801, United States
4. Department of Biochemistry, University of Illinois, Urbana, Illinois 61801, United States
5. Arnold and Mabel Beckman Institute, University of Illinois, Urbana, Illinois 61801, United States
6. Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United States