1. Laboratory of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
2. Department of Genetics and Microbiology, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy
3. Biomolecular and Mass Spectrometry and Proteomics Group, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands