Modification of DNA damage mechanisms by nitric oxide during ionizing radiation

► Nitric oxide reacts with hydroxyl radical-induced guanine radicals to form xanthine and 8-azaguanine. ► Mechanisms of guanine radical reactions with nitric oxide are discussed. ► Radiosensitization of cells by NO may involve DNA base modifications. ► The DNA base modifications can lead to replication-induced DNA strand breaks.