1. Department of Chemistry, Western Washington University, 516 High Street, Bellingham, Washington 98225-9150, United States
2. Department of Biology, Western Washington University, 516 High Street, Bellingham, Washington 98225-9160, United States
3. Department of Biochemistry and Molecular Biology, Department of Chemistry, and Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
4. Department of Physiology and Biophysics, Boston University School of Medicine, 700 Albany Street, Boston, Massachusetts 02118-2526, United States
5. Department of Chemistry, University of Colorado at Denver, Denver, Colorado 80204, United States