Interaction of several Ni(III) complexes of peptides with DNA; analysis by DNA-fiber EPR.

EPR spectra of Ni(III) complexes of GGH, GHG, and GHK were obtained by in-situ oxidation of the Ni(II) complexes in DNA-pellet and on DNA-fibers. A species with an apical coordination of nitrogenous base of DNA was detected for Ni(III) GGH. Both GHG and GHK complexes showed the EPR signals of Ni(III) species when the ligand to metal ion ratio was 2:1. The complexes bind as Ni(III)(N6), NI(III)(N5), and Ni(III)(N4) species on DNA.