1. Department of Biochemistry ‘A. Castellani’, University of Pavia, via Taramelli 3b, 27100 Pavia, Italy
2. Department of Organic Chemistry and Biochemistry, University of Naples ‘Federico II’, via Cynthia 6, 80126 Naples, Italy
3. Biocrystallography Laboratory, Department of Science and Technology, University of Verona, Ca Vignal 1, strada Le Grazie 15, 37134 Verona, Italy