*H atom and *OH radical reactions with 5-methylcytosine.
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.
Grand
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Laboratoire Lésions des Acides Nucléiques, DRFMC/SCIB, UMR-E 3 (CEA/UJF), CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France.
Morell
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Labet
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Cadet
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Eriksson
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D044503:5-Methylcytosine / Q000737:chemistry*; D003198:Computer Simulation; D006859:Hydrogen / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D015394:Molecular Structure; D016877:Oxidants / Q000737:chemistry; D013816:Thermodynamics
D016877:Oxidants; D017665:Hydroxyl Radical; D044503:5-Methylcytosine; D006859:Hydrogen