1. Institute of Molecular Biology and Pathology, CNR Piazzale A. Moro 5 00185 Rome Italy
2. Institute of Biophysics of the Czech Academy of Sciences Královopolská 135 61265 Brno Czech Republic
3. Department of Biology University of Padua (Italy) On leave at: Centro Linceo “Beniamino Segre” Accademia Nazionale dei Lincei via della Lungara 10 00165 Rome Italy
4. Center for Life NanoSciences Istituto Italiano di Tecnologia (IIT) Viale Regina Elena 291 00166 Rome Italy
5. Department of Physics Sapienza University of Rome Piazzale Aldo Moro 2 00185 Rome Italy