Complexes of DNA with trivalent metal ions in presence of manganese ions

The interaction of DNA with Fe3+, Al3+, Co(NH3)6(3+) in a solution containing MnCl2 was studied. It was shown that there exists a competition for the binding sites between Mn2+ and Al3+, while the binding of Mn2+ to DNA does not depend on the presence of Fe3+ and Co(NH3)6(3+) in solution. We proposed that Fe3+ and Co(NH3)6(3+) ions prefer to bind to phosphates, and Al3+ ions are capable to bind to the nitrogen bases of DNA.