title: *H atom and *OH radical reactions with 5-methylcytosine.
abstract: 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.
authors.affiliation: Laboratoire Lésions des Acides Nucléiques, DRFMC/SCIB, UMR-E 3 (CEA/UJF), CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France.
authors.forename: A
authors.initials: A
authors.lastname: Grand
authors.forename: C
authors.initials: C
authors.lastname: Morell
authors.forename: V
authors.initials: V
authors.lastname: Labet
authors.forename: J
authors.initials: J
authors.lastname: Cadet
authors.forename: L A
authors.initials: LA
authors.lastname: Eriksson
mesh_terms: 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
chemical_list: D016877:Oxidants; D017665:Hydroxyl Radical; D044503:5-Methylcytosine; D006859:Hydrogen