Mn-TMPyP/KHSOs

Velikyan I, Acharya S, Trifonova A, Foldesi A, Chattopadhyaya J (2001) The pffas of 2 -hydroxyl group in nudeosides and nucleotides. J Am Chem Soc 123 2893-2894 Veltwisch D, Asmus K-D (1982) On the reaction of methyl and phenyl radicals with p-benzoquinone in aqueous solution. J Chem Soc Perkin Trans 2 1147-1152 Vialas C, Pratviel G, Claparols C, Meunier B (1998) Efficient oxidation of 2 -deoxyguanosine by Mn-TMPyP/KHSOs to imidazolone dlz without formation of 8-oxo-dG. J Am Chem Soc 120 11548-11553... 

Fig. 6. Mechanism for the cleavage of DNA or DNA models after hydroxylation of C-H bonds on the 1 and 5 positions of deoxyribose by Cu(phen)2/H202 (route A) or Mn-TMPyP/KHSOs (routes A and B) (A = thermal step, B = base, BE = /3 elimination).

First, a simplified model of DNA, polydeoxyadenylic acid, was shown to be readily cleaved at neutral pH by Mn-TMPyP/KHSOs with spontaneous release of free adenine and, after heating, formation of a rather unstable sugar degradation product identified as 5-methylene-2(5H)-furanone, supporting a C-1 oxidation pathway. The first /3-elimination created a 5 -phosphate end and the second one was accompanied by 5-MF release. The two DNA strands were terminated by phosphate groups (Fig. 6, route A) (282). 

Pitie, M., Bemadou, J., Meunier, B. (1995). Oxidation at carbon-1 of DMA deoxyriboses by the Mn-TMPyP/KHSO, system results from a cytochrome P-450-type hydroxy-lation reaction, J. Am. Chem. Soc., 117 2935. 

Fig. 25. Mechanism of Cl and C5 direct hydroxylation of deoxyribose mediated by the Mn =0 species of Mn-TMPyP in the presence of KHSOs. a stands for Mn-TMPyP + KHSOs oxidation. A refers to a heating step at 90°C at pH = 8 for 15 min. To be compared with Figs 4 and 8.

The C4 oxidation was never detected with the Mn-TMPyP/KHSOs system on double-stranded DNA. The classical base propenals 13 (208) or the related... 

On the contrary, in the case of the oxidation of dG by Mn-TMPyP/KHSOs, the formation of diz was not dependent upon the presence of molecular oxygen. Furthermore, LC/ESI-MS analysis of the reaction showed that when the reaction was performed in the presence of labeled molecular oxygen ( 62) diz was not labeled. The fact that no intermediate radical species was trapped by molecular oxygen indicated that the radical intermediate due to a one-electron oxidation of guanine, (G-H), was rapidly further oxidized, in this reaction medium, into a non-radical cationic species, (G-H) . This second electron abstraction is faster than the trapping by molecular oxygen. The non-radical cationic species was to be trapped by nucleophiles. However, when the reaction was performed in labeled water H2 0, diz did... 

Fig. 29. LC/ESI-MS analysis of the oxidation of a short double-stranded oligonucleotide by Mn-TMPyP/KHSOs. ODN I stands for the self complementary oligonucleotide 5 -CAGCTG. The oxidation was carried out in 50 mM Tris/HCl buffer pH = 7, NaCl 100 mM with the following concentrations of reactants duplex ODN I, Mn-TMPyP, KHSO5, 200 pM, 200 pM, 2mM, respectively. The reaction lasted 5 min at 0°C. A HPLC trace B in-line ESI-MS spectrum of ODN I (retention time, 44.5 min).

Fig. 30. Products of guanine oxidation in double-stranded oligonucleotides generated by Mn-TMPyP/KHSOs. Incorporation of labeled oxygen atoms in the products of...

Pitie M, Bemadou J, Meunier B. Oxidation of carbon-T of DNA deoxytiboses by the Mn-TMPYP/KHSOs system results from a cytochrome p-450-type hydroxylation reaction. J clm Chem Soc. 1995 117 2935—2936. 

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