Meso-tetrakis(4-N-methylpyridiniumyl)porphyrinatomanganese (III) (Mn-TMPyP) and its iron(III) analogue (Fe-TMPyP)when activated by dissymmetric peroxide such as KHSO5 become powerful oxidant. High-valent manganese-oxo and iron-oxo porphyrins mimic oxidation reaction mechanism of natural heme enzymes namely cytochrome P450 and peroxidases to oxidize short stranded oligonucleotides. Cytochrome P450 bears an anionic thiolate molecule (from cysteine) as proximal axial ligand that directs its reactivity towards oxygen atom transfer mechanism. Peroxidases have a neutral proximal axial ligand, imidazole (from histidine); that mediates an electron transfer mechanism. Using DNA as substrate it was shown that Mn-TMPyP/KHSO5 at pH 6 with water as proximal axial ligand behaves like a peroxidase while it mimics cytochrome P450 chemistry at pH 8 with an hydroxo axial ligand. FeTMPyP/KHSO5 exists as a �-oxo species in solution; thus it reacts mainly by oxygen atom transfer mechanism.

Oxidation of DNA by high-valent metal-oxo porphyrins Mn-TMPyP and Fe-TMPyP

247th National Meeting (2014)

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