1. Department of Biochemistry, The University of Western Ontario, London, ON, Canada
2. Department of Chemistry, The University of Western Ontario, London, ON, Canada
3. Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
4. Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
5. Department of Chemistry, Yale University, New Haven, CT, USA