Radicaux Libres Radioinduits Dans les Solutions Gelées de 5-méthylcytosine

Lion, Yves; Vorst, A. Van de

doi:10.1080/09553007414550711

Cited by 3 publications

(1 citation statement)

References 6 publications

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“…Altogether the kinetic and structural data thus obtained allow the proposal of comprehensive radical oxidative degradation pathways for the main DNA nucleobases. This provides basic information needed for a better understanding of the molecular effects of endogenously generated • OH radicals and environmental oxidizing agents including ionizing radiation and UVA light on cellular DNA. , In contrast there is still a relative paucity of information on both the • OH radical- and • H atom-mediated reactions of 5-methylcytosine (5-MeCyt) , present in DNA as the result of enzymatic methylation of cytosine residues to the extent of a few percent. Despite its low abundance, 5-MeCyt appears to play a major biological role since mutational hotspots have been observed in, for example, the key p53 tumor suppressor gene at methylated CpG sites .…”

Section: Introductionmentioning

confidence: 99%

^•H Atom and ^•OH Radical Reactions with 5-Methylcytosine

et al. 2007

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The reactions between either a hydrogen atom or a hydroxyl radical and 5-methylcytosine (5-MeCyt) are studied by using the hybrid kinetic energy meta-GGA functional MPW1B95. *H atom and *OH radical addition to positions C5 and C6 of 5-MeCyt, or *OH radical induced H-abstraction from the C5 methyl group, are explored. All systems are optimized in bulk solvent. The data presented show that the barriers to reaction are very low: ca. 7 kcal/mol for the *H atom additions and 1 kcal/mol for the reactions involving the *OH radical. Thermodynamically, the two C6 radical adducts and the *H-abstraction product are the most stable ones. The proton hyperfine coupling constants (HFCC), computed at the IEFPCM/MPW1B95/6-311++G(2d,2p) level, agree well with B3LYP results and available experimental and theoretical data on related thymine and cytosine radicals.

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Section: Introductionmentioning

confidence: 99%

^•H Atom and ^•OH Radical Reactions with 5-Methylcytosine

et al. 2007

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Free-Radical Damage of Nucleic Acids and Their Components: The Direct Absorption of Energy

Myers¹

1980

Free Radicals in Biology

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Synthesis of stable-isotope enriched 5-methylpyrimidines and their use as probes of base reactivity in DNA

Burdzy¹

2002

Nucleic Acids Research

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A specific and efficient method is presented for the conversion of 2'-deoxyuridine to thymidine via formation and reduction of the intermediate 5-hydroxymethyl derivative. The method has been used to generate both thymidine and 5-methyl-2'-deoxycytidine containing the stable isotopes 2H, 13C and 15N. Oligodeoxyribonucleotides have been constructed with these mass-tagged bases to investigate sequence-selectivity in hydroxyl radical reactions of pyrimidine methyl groups monitored by mass spectrometry. Studying the reactivity of 5-methylcytosine (5mC) is difficult as the reaction products can deaminate to the corresponding thymine derivatives, making the origin of the reaction products ambiguous. The method reported here can distinguish products derived from 5mC and thymine as well as investigate differences in reactivity for either base in different sequence contexts. The efficiency of formation of 5-hydroxymethyluracil from thymine is observed to be similar in magnitude in two different sequence contexts and when present in a mispair with guanine. The oxidation of 5mC proceeds slightly more efficiently than that of thymine and generates both 5-hydroxymethylcytosine and 5-formylcytosine but not the deaminated products. Thymine glycol is generated by both thymine and 5mC, although with reduced efficiency for 5mC. The method presented here should be widely applicable, enabling the examination of the reactivity of selected bases in DNA.

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Radicaux Libres Radioinduits Dans les Solutions Gelées de 5-méthylcytosine

Cited by 3 publications

References 6 publications

^•H Atom and ^•OH Radical Reactions with 5-Methylcytosine

^•H Atom and ^•OH Radical Reactions with 5-Methylcytosine

Free-Radical Damage of Nucleic Acids and Their Components: The Direct Absorption of Energy

Synthesis of stable-isotope enriched 5-methylpyrimidines and their use as probes of base reactivity in DNA

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Radicaux Libres Radioinduits Dans les Solutions Gelées de 5-méthylcytosine

Cited by 3 publications

References 6 publications

•H Atom and •OH Radical Reactions with 5-Methylcytosine

•H Atom and •OH Radical Reactions with 5-Methylcytosine

Free-Radical Damage of Nucleic Acids and Their Components: The Direct Absorption of Energy

Synthesis of stable-isotope enriched 5-methylpyrimidines and their use as probes of base reactivity in DNA

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^•H Atom and ^•OH Radical Reactions with 5-Methylcytosine

^•H Atom and ^•OH Radical Reactions with 5-Methylcytosine