活性酸素による8-ヒドロキシグアニンの生成と生体との関わり : 変異誘発・発がん・修復

Reactive oxygen species (ROS) are produced by the normal oxygen metabolism in cells as a consequence of respiration in an oxygen atmosphere and by some kinds of environmental mutagens. ROS attack and modify cellular macromolecules including DNA. 8-Hydroxyguanine (8-OH-Gua) is one of the DNA lesions which are produced by ROS. 8-OH-Gua mainly induces G→T mutations in vitro, in E. coli and mammalian cells. Repair enzymes for 8-OH-Gua are present in cells and prevent the mutations induced by the DNA lesion. Formation of oxidative DNA lesions which are produced by ROS appears to be involved in many biological processes including carcinogenesis and ageing. Therefore, 8-OH-Gua may be a good marker of cellular production of ROS to estimate mutagenicities and carcinogenicities of chemical compounds.