1. Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ (UK)
2. School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (UK)
3. School of Biological Sciences, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ (UK)