Institute of Biophysics, National Research Council, Palermo, Italy.|Institute of Biophysics, National Research Council, Palermo, Italy.|Institute of Biophysics, National Research Council, Palermo, Italy.|Institute of Biophysics, National Research Council, Palermo, Italy.|Institute of Biophysics, National Research Council, Palermo, Italy.|Institute of Biophysics, National Research Council, Palermo, Italy.