Affiliation: | a Massachusetts Institute of Technology, Department of Chemistry, 77 Massachusetts Avenue, Cambridge, MA 02139, USA b Karlsruhe Institute of Technology, Institute of Organic Chemistry, Fritz-Haber-Weg 6, 76137 Karlsruhe, Germany c The John Innes Centre, Department of Biological Chemistry, Norwich NR4 7UH, UK d The University of East Anglia, Norwich NR4 7TJ, UK |