1. Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
2. Department of Biology and Biotechnology, University of Pavia, Via Ferrata 1, 27100, Pavia, Italy
3. Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands