1. Department of Biochemistry, McGill University, Montreal, Quebec H3G1Y6, Canada
2. Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N6N5, Canada
3. Department of Chemistry, McGill University, Montreal, Quebec H3A0B8, Canada
4. Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G2R7, Canada