Interaction of the cobalt complex of a bleomycin functional model with d(CGCAATTGCG)2: evidence of minor groove binding by 2D NMR methods.

The interaction between the cobalt complex of a bleomycin functional model and d(CGCAATTGCG)2 was determined by 2D NMR methods. The intermolecular NOE cross peaks between ligand protons and the DNA minor groove protons suggest that the cobalt complex of AMPHIS-NET binds in the minor groove of DNA at the central AATT site. Also, the NOEs interactions of H8 pyridine proton and H2 imidazole proton in the metal-binding domain with H4' sugar proton of C9 and H4' sugar proton of A15 demonstrate that the sixth ligand site of cobalt complex, which is occupied by a solvent molecule, faces towards the minor groove of DNA. This binding model is in accord with the observed non-diffusion DNA cleavage by the metal-complexes of the bleomycin functional model compounds.