Chemical nature of in vivo DNA base damage in hydrogen peroxide-treated mammalian cells.

Hydrogen peroxide is generated in mammalian cells by normal metabolism or by treatment with external agents. Treatment of mammalian cells with this oxidizing agent results in DNA damage. Little is known about the chemical nature of hydrogen peroxide-mediated DNA damage in mammalian cells. Here we report on the chemical characterization of in vivo base damage to nuclear DNA in mammalian cells caused by exposure to H2O2. Chromatin was isolated from cells and analyzed by gas chromatography/mass spectrometry with selected-ion monitoring. Ten DNA base products were identified and quantitated. Modified bases identified were typical hydroxyl radical-induced products of DNA bases. Results indicate involvement of hydroxyl radicals in the mechanism of nuclear DNA damage in mammalian cells caused by H2O2.