1. Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone 16, I-80134 Naples, Italy, Department of Chemistry, University of Naples “Federico II”, Complesso Universitario Monte S. Angelo, Via Cinthia, I-80126 Naples, Italy, Institute of Protein Biochemistry, CNR, Via Pietro Castellino 111, I-80131 Naples, Italy, and Department of Chemistry, University of Florence, Via della Lastruccia 3, I-50019 Sesto Fiorentino (FI), Italy