*H atom and *OH radical reactions with 5-methylcytosine

J Phys Chem A. 2007 Sep 20;111(37):8968-72. doi: 10.1021/jp0737799. Epub 2007 Aug 28.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5-Methylcytosine / chemistry*
  • Computer Simulation
  • Hydrogen / chemistry*
  • Hydroxyl Radical / chemistry*
  • Molecular Structure
  • Oxidants / chemistry
  • Thermodynamics

Substances

  • Oxidants
  • Hydroxyl Radical
  • 5-Methylcytosine
  • Hydrogen