Effects of a 8-oxoadenosine Incorporation on Quadruplex structures: thermal stabilities and structural studies

The effects of incorporation of 8-oxoadenosine in two different truncations of human telomeric sequence forming quadruplex structures are reported. In order to characterize their structures, a combination of NMR and UV spectroscopy and computational techniques were used. Both oligonucleotides have been found to form four-fold sym. quadruplex structures. As a tautomeric equil. between keto and enol forms of 8-oxoadenosine may establish in soln. and intrinsic stabilities effects, such as internal H-bonds, for example, may det. the predominance of some particular tautomer, mol. modeling studies were performed on quadruplex structures contg. both the tautomeric forms. Both mols. resulted to be thermally less stable than the natural.