1. Department of Chemistry Simon Fraser University Burnaby BC V5A 1S6 Canada
2. York Structural Biology Laboratory Department of Chemistry University of York York YO10 5DD UK
3. Children's Medical Research Institute The University of Sydney Sydney NSW 2145 Australia
4. Department of Molecular Biology and Biochemistry Simon Fraser University Burnaby BC V5A 1S6 Canada
5. Chemistry, School of Environmental and Life Sciences The University of Newcastle University Drive Callaghan NSW 2308 Australia