title: Chemical modification of DNA: quantitation of O6-methyldeoxyguanosine by tandem mass spectrometry.
abstract: Methodology is described which allows quantitation of O6-methyldeoxyguanosine generated as a product of in vitro methylation of calf thymus DNA by methyl methanesulfonate (MeMS). Quantitative precision of 10% is achieved on samples of 10(-11)-10(-12) mol generated in 0.02% yield (expressed as O6-methyldeoxyguanosine versus deoxyguanosine) when DNA is treated with the weak carcinogen MeMS. These results show the potential application of this method to the analysis of DNA chemical modifications at the low levels that are relevant to the induction of biological effects of many alkylating agents. The methodology utilizes enzymatic degradation, reverse-phase chromatography and finally analysis by tandem mass spectrometry using desorption chemical ionization. Multiple reaction monitoring was used to increase sensitivity and the CD3-labeled nucleoside was used as an internal standard for quantification.
authors.forename: W G
authors.initials: WG
authors.lastname: Chae
authors.forename: C J
authors.initials: CJ
authors.lastname: Chang
authors.forename: J M
authors.initials: JM
authors.lastname: Wood
authors.forename: R G
authors.initials: RG
authors.lastname: Cooks
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000737:chemistry*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000032:analysis; D013058:Mass Spectrometry
chemical_list: D004247:DNA; C015558:O(6)-methyl-2'-deoxyguanosine; D003849:Deoxyguanosine