1. Institute of Biotechnology, Norwegian University of Science and Technology, Sem Sælands V. 6/8, 7491 Trondheim, Norway, Department of Biochemistry, Biophysics and Macromolecular Chemistry, University of Trieste, Via Licio Giorgieri 1, 34127 Trieste, Italy, Department of Chemistry, University of Rome “La Sapienza”, Rome, Italy