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  • Title: Use of short duplexes for the analysis of the sequence-dependent cleavage of DNA by a chemical nuclease, a manganese porphyrin.
    Author: Mourgues S, Kupan A, Pratviel G, Meunier B.
    Journal: Chembiochem; 2005 Dec; 6(12):2326-35. PubMed ID: 16276504.
    Abstract:
    A manganese porphyrin, manganese(III)-bis(aqua)-meso-tetrakis(4-N-methylpyridiniumyl)porphyrin, in the presence of KHSO5 is able to perform deoxyribose or guanine oxidation depending on its mode of interaction with DNA. These two reactions involve an oxygen-atom transfer or an electron transfer, respectively. The oxidative reactivity of the manganese-oxo porphyrin was compared on short oligonucleotide duplexes of different sequences. The major mechanism of DNA damage is due to deoxyribose hydroxylation at a site of strong interaction, an (A.T)3 sequence. Guanine oxidation by electron transfer was found not to be competitive with this major mechanism. It was found that a single intrastrand guanine was three orders of magnitude less reactive than an (A.T)3 sequence. The reactivity of a 5'-GG sequence was found to be intermediate and was estimated to be two orders of magnitude less than that of an (A.T)3 site. Short oligonucleotide duplexes, as double-stranded-DNA models, proved to be convenient tools for the study of the comparative reactivity of this reagent toward different sequences of DNA. However, they showed a particular reactivity at their terminal base pairs (the "end effect") that biased their modeling capacity for double-helix-DNA models.
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