title: Characterizing DNA photo-oxidation reactions by high-resolution mass measurements with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
abstract: High-resolution mass measurements by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry were employed to characterize laser-induced oxidation of guanine in a small synthetic deoxyoligonucleotide. The oligonucleotide was exposed to high-intensity UV radiation at 266 nm to produce modifications on the guanine base. The primary product showed a +16 Da mass shift relative to the original strand, whereas secondary products showed mass shifts of +32 and +34 Da. The mass shift of the primary product is consistent with an 8-oxoguanine modification. However, the reactivity of the primary product with hot piperidine and other secondary oxidizing agents was different from that of a synthetic oligonucleotide containing 7,8-dihydro-8-oxo-2'-deoxyguanine (8-oxoG). Based upon the results, a new reaction scheme involving the formation of an epoxide ring across the C-4 and C-5 positions by UV laser-induced oxidation is suggested. The results also illustrate the ability of MALDI to characterize chemical reactivity rapidly at the a low picomolar level.
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark 19716, USA.
authors.forename: W P
authors.initials: WP
authors.lastname: Bartolini
authors.forename: M V
authors.initials: MV
authors.lastname: Johnston
mesh_terms: D001483:Base Sequence; D004249:DNA Damage; D066298:In Vitro Techniques; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000528:radiation effects; D010084:Oxidation-Reduction; D010777:Photochemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D009838:Oligodeoxyribonucleotides