1. Max Planck Research Group Nucleic Acid Chemistry; Max Planck Institute for Biophysical Chemistry; Am Fassberg 11 37077 Göttingen Germany
2. Department of Biology; Faculty of Sciences; University of Isfahan; Isfahan Iran
3. Institute for Organic and Biomolecular Chemistry; Georg-August-University Göttingen; Tammannstrasse 2 37077 Göttingen Germany