1. School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)
2. Department of Microbiology, University of Manitoba, 45 Chancellors Circle, Winnipeg, MB R3T2N2 (Canada)
3. Current address: Bioscience Division, Los Alamos National Laboratory, P. O. Box 1663, Los Alamos, NM 87545 (USA)
4. Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A1S6 (Canada)
5. Current address: Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA)
6. Current address: Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST (UK)