Interaction of DNA with coordination compounds of bivalent platinum .3. Platinum compounds with two pyrimidine ligands

The interaction of DNA with coordination compounds of bivalent platinum containing 5-substituted uracil ligands (R = H, Br, NO2) was studied. For all title complexes, the mode of interaction with DNA in solution is virtually unaffected by the nature of the substituent. Ionic strength has only a slight effect on complex formation. The platinum compounds alter the optical anisotropy of DNA but have no influence on its circular dichroism and hydrodynamic parameters. It is assumed that the platinum complexes bind to the macromolecule so that the pyrimidine ligands are on the periphery of the double helix. It is possible in this case that the NH3 groups form hydrogen bonds with the phosphate oxygens.