ABSTRACT
Considerable interest has arisen in recent years in the formation and consequences of oxidative damage to DNA. Reactive oxygen species (ROS) and free radicals have been suggested to play a role in biological processes such as carcinogenesis and aging (1,2). This interest is derived in part from the realization that ROS form inside cells as a byproduct of normal cell metabolism (3). ROS such as hydroxyl radical (OH*) or singlet oxygen (]O2) are highly reactive and produce a complex pattern of DNA modifications (4). For example OH' radical causes a variety of DNA damage including base modifications, abasic sites, DNA strand breaks, and cross-links (5). Several lines of evidence suggest that an oxidatively damaged form of guanine, 7,8-dihydro-8-oxoguanine (8-OxoG) threatens the integrity of genetic information and may be used as a model lesion to study the biological impact of endogenous oxidative stress.
