title: Nontargeted analysis of DNA adducts by mass-tag MS: reaction of p-benzoquinone with DNA.
abstract: Using a method in which DNA adducts are discovered based on their conversion in a nucleotide form to phosphorimidazolides with isotopologue benzoylhistamines (or p-bromobenzoylhistamine) prior to detection by MALDI-TOF-MS, we have profiled the adducts that form when calf thymus DNA is reacted in vitro with p-benzoquinone (BQ). We find, as relative values normalized to 100% of adducts observed, 79% BQ-dCMP, 21% BQ-methyl-dCMP (a new DNA adduct), and trace amounts of BQ-dAMP and BQ-dGMP. Because mC is 5% of C in this DNA, the reaction of BQ with DNA in vitro is about five times faster at methyl-C than C. When equal amounts of dCMP and methyl-dCMP are reacted with BQ, equal amounts of the corresponding adducts are observed. Thus, the microenvironment of methyl-C in DNA enhances its reactivity relative to C with BQ. In a prior, similar study, but based on analysis by (32)P-postlabeling, the second most abundant adduct was assigned to BQ-A, apparently because of comigration of the BQ-A and BQ-methyl-C adducts (as bisphosphates) in the chromatographic step. Because the calf thymus DNA (used as received) was contaminated with RNA, we also detected the ribonucleotide adduct, BQ-CMP.
authors.affiliation: Department of Pharmaceutical Sciences and Barnett Institute, Northeastern University, Boston, Massachusetts 02115, United States.
authors.forename: Poguang
authors.initials: P
authors.lastname: Wang
authors.forename: Jianxin
authors.initials: J
authors.lastname: Gao
authors.forename: Guodong
authors.initials: G
authors.lastname: Li
authors.forename: Olga
authors.initials: O
authors.lastname: Shimelis
authors.forename: Roger W
authors.initials: RW
authors.lastname: Giese
mesh_terms: D000818:Animals; D016227:Benzoquinones / Q000378:metabolism*; D002417:Cattle; D004247:DNA / Q000378:metabolism*; D018736:DNA Adducts / Q000032:analysis*; D003854:Deoxyribonucleotides / Q000378:metabolism*; D007202:Indicators and Reagents / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods
chemical_list: D016227:Benzoquinones; D018736:DNA Adducts; D003854:Deoxyribonucleotides; D007202:Indicators and Reagents; C004532:quinone; D004247:DNA; C427203:calf thymus DNA