1. CERM, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Italy
2. Department of Chemistry “U. Schiff”, University of Florence, via della Lastruccia 3, 50019, Sesto Fiorentino, Italy
3. Department
of Biophysics, University of Michigan, 830 N. University, Ann Arbor, Michigan 48109, United States
4. Department
of Biochemistry and Department of Chemistry, Duke University School of Medicine, 307 Research Drive, Durham, North Carolina 27710, United States