Regulation of orientation and the dynamic behavior of metal complexes bound to DNA

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In order to develop effective reagents that cleave DNA oxidatively or hydrolytically, various metal complexes have been synthesized and the reactivity and the DNA binding structures have been investigated.1. Several copper(II) complexes with 4-dentate phenanthroline derivatives with substituents at 2- and 9-postions were synthesized. Bulky substituents that deformed the planarity of the complex enhanced the oxidative cleavage of DNA and the correlation between the reactivity and the binding structure was discussed.2. In the cleaving reaction with ternary copper(II) complexes with phenanthroline and amino acid, the amino acid depresses the reaction. Further lowering of the reactivity was induced by 2,9-dimethyl substituted phenanthroline. These results suggested that cleaving reaction proceeds with the mono-phenanthroline copper(II) complex.3. Binding structures of the ternary platinum(II) complexes of phenanthroline or dipyridine with lysine bound to oligonucleotide DO1 and DO2 were analyzed by NMR. The phenanthroline derivative intercalates between G2 and C3 of DO1 and G4 and A5 of DO2 from the minor groove while the bipyridine derivative binds to the AT site of DO1 in the minor groove. The binding structures were refined by molecular dynamic calculation.4. ESR signals from unstable Ni(III) complexes of histidine-containing tripeptides could be detected by in-situ oxidation of the Ni(II) complex incorporated in DNA. The super-hyperfine splitting from nitrogenous base suggested a presence of the species coordinated to a guanine N7.