1. Department of Macromolecular Biochemistry Leiden Institute of Chemistry Einsteinweg 55 2333 CC Leiden The Netherlands
2. Institute of Structural and Molecular Biology University College London and Birkbeck College London WC1E 6BT UK
3. VIB-VUB Center for Structural Biology Pleinlaan 2 1050 Brussels Belgium
4. Jean Jeener NMR Centre VUB Pleinlaan 2 1050 Brussels Belgium
5. Department of Bio-organic Synthesis Leiden Institute of Chemistry Einsteinweg 55 2333 CC Leiden The Netherlands
6. ZoBio BV BioPartner 2 building J.H. Oortweg 19 2333 CH Leiden The Netherlands
7. Department of Medical Biochemistry Leiden Institute of Chemistry Einsteinweg 55 2333 CC Leiden The Netherlands
8. Present address: NMR Spectroscopy Research Group Bijvoet Center for Biomolecular Research Utrecht University Padualaan 8 3584 CH Utrecht The Netherlands