1. Dulbecco Telethon Institute, Biomolecular NMR Laboratory c/o Center of Genomics, Bioinformatics and Biostatistics, S. Raffaele Scientific Institute, Via Olgettina 58, 20132, Milano (Italy), Fax: (+39) 0226434153
2. Present address: Protein Dynamics and Flexibility by NMR, Institut de Biologie Structurale, 41 Rue Jules Horowitz, Grenoble 38027 (France)
3. Istituto di Chimica del Riconoscimento Molecolare, Consiglio nazionale delle Ricerche, Via Mario Bianco 9, 20131, Milano (Italy)