1. Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
2. Department of Biochemistry & Microbiology, University of Victoria, P.O. Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada
3. Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
4. Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada