Radical‐mediated cytosine and 5‐methylcytosine hydrolytic deamination reactions

Abstract The mechanisms of cytosine and 5‐methylcytosine hydrolytic deamination reactions in the gas phase have been investigated. The rate‐determining steps of the reactions are found by density functional theory (DFT). The lower barriers of hydrogen and hydroxyl radical‐mediated 5‐methylcytosine deamination make the C‐5 site of 5‐methylcytosine the hot spot for spontaneous mutations. The hydrogen radical inhibits cytosine and 5‐methylcytosine hydrolytic deamination reactions, while the hydroxyl radical clearly leads to an increased risk of genetic mutagenesis. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006