The binding structures of several paramagnetic metal complexes of 5,10,15,20-tetrakis(1-methyl-4-or -2-pyridinio) porphyrin (H2L 1 or H2L2) on the highly oriented DNA fibres were investigated by means of ESR spectroscopy and computer simulations of the spectra. The structural parameters characteristic of the sterospecific groove binding were obtained for [CuL2]Cl4, high-spin [FeCl(L1)]Cl4 and low-spin [CoL1] [ClO 4]4 and the low-spin monoimidazole adduct [CoL 1(Him)] [ClO4]4. They bind to the DNA with the normals of the porphyrin planes titled by about 45° from the double helix axes. The low-spin bis(imidazole) adduct [FeCl(L1) (Him) 2]Cl4 binds to A-form DNA with the porphyrin plane nearly parallel to the double helix axis. The complex [CoL1] [ClO 4]4 binds to DNA as an intercalator as well as a groove binder. It was also revealed that some metalloporphyrins stabilize the tertiary structures of DNA around the binding sites.
|Number of pages||7|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|Publication status||Published - 1995 Dec 1|
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