title: Electron photodetachment dissociation of DNA polyanions in a quadrupole ion trap mass spectrometer.
abstract: We hereby explore the effects of irradiating DNA polyanions stored in a quadrupole ion trap mass spectrometer with an optical parametric oscillator laser between 250 and 285 nm. We studied DNA 6-20-mer single strands and 12-base pair double strands. In all cases, laser irradiation causes electron detachment from the multiply charged DNA anions. Electron photodetachment efficiency directly depends on the number of guanines in the strand, and maximum efficiency is observed between 260 and 275 nm. Subsequent collision-induced dissociation (CID) of the radical anions produced by electron photodetachment results in extensive fragmentation. In addition to neutral losses, a large number of fragments from the w, d, a*, and z* ion series are obtained, contrasting with the w and (a-base) ion series observed in regular CID. The major advantage of this technique, coined electron photodetachment dissociation (EPD) is the absence of internal fragments, combined with good sequence coverage. EPD is therefore a highly promising approach for de novo sequencing of oligonucleotides. EPD of nucleic acids is also expected to give specific radical-induced strand cleavages, with conservation of other fragile bonds, including noncovalent bonds. In effect, preliminary results on a DNA hairpin and on double strands suggest that EPD could also be used to probe intra- and intermolecular interactions in nucleic acids.
authors.affiliation: Laboratoire de Spectrométrie de Masse, Université de Liège, Institut de Chimie, Bat B6c, B-4000 Liège, Belgium. v.gabelica@ulg.ac.be
authors.forename: Valérie
authors.initials: V
authors.lastname: Gabelica
authors.forename: Thibault
authors.initials: T
authors.lastname: Tabarin
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Antoine
authors.forename: Frédéric
authors.initials: F
authors.lastname: Rosu
authors.forename: Isabelle
authors.initials: I
authors.lastname: Compagnon
authors.forename: Michel
authors.initials: M
authors.lastname: Broyer
authors.forename: Edwin
authors.initials: E
authors.lastname: De Pauw
authors.forename: Philippe
authors.initials: P
authors.lastname: Dugourd
mesh_terms: D004247:DNA / Q000737:chemistry* / Q000528:radiation effects; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000528:radiation effects; D010777:Photochemistry; D017422:Sequence Analysis, DNA / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D004277:DNA, Single-Stranded; D004247:DNA