1. Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11 Göttingen 37077 Germany
2. Laboratory of Genetics, Department of Biology MCA, University of Camerino Gentille III da Varano Camerino 62032 Italy
3. Department of Molecular and Radiation Biophysics, Petersburg Nuclear Physics Institute Gatchina 188300 Russia