1. Department of Bioorganic Chemistry; Leiden Institute of Chemistry; Einsteinweg 55 2333 CC Leiden The Netherlands
2. Department of Medical Biochemistry; Leiden Institute of Chemistry; Einsteinweg 55 2333 CC Leiden The Netherlands
3. Department of Chemistry, York Structural Biology Laboratory; University of York; Heslington York YO10 5DD UK
4. School of Chemistry and Bio21 Molecular Science and Biotechnology Institute; University of Melbourne; Parkville Victoria Australia