1. Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy, Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy, Department of Agricultural Biotechnology, University of Florence, Via Donizetti 6, 50144 Florence, Italy, and ProtEra, Viale delle Idee 22, 50019 Sesto Fiorentino, Italy