title: UV spectroscopy of DNA duplex and quadruplex structures in the gas phase.
abstract: UV absorption spectroscopy is one of the most widely used methods to monitor nucleic acid folding in solution, but the absorption readout is the weighted average contribution of all species present in solution. Mass spectrometry, on the other hand, is able to separate constituents of the solution based on their mass, but methods to probe the structure of each constituent are needed. Here, we explored whether gas-phase UV spectroscopy can give an indication of DNA folding in ions isolated by electrospray mass spectrometry. Model DNA single strands, duplexes, and G-quadruplexes were extracted from solution by electrospray; the anions were stored in a quadrupole ion trap and irradiated by a tunable laser to obtain the UV action spectra of each complex. We found that the duplex and quadruplex spectra are significantly different from the spectra of single strands, thereby suggesting that electronic spectroscopy can be used to probe the DNA gas-phase structure and obtain information about the intrinsic properties of high-order DNA structure.
authors.affiliation: Département de Chimie, Université de Liège, Building B6c, 3, allée de la chimie, 4000 Liège, Belgium. f.rosu@ulg.ac.be
authors.forename: Frédéric
authors.initials: F
authors.lastname: Rosu
authors.forename: Valérie
authors.initials: V
authors.lastname: Gabelica
authors.forename: Edwin
authors.initials: E
authors.lastname: De Pauw
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Antoine
authors.forename: Michel
authors.initials: M
authors.lastname: Broyer
authors.forename: Philippe
authors.initials: P
authors.lastname: Dugourd
mesh_terms: D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry*; D054856:G-Quadruplexes; D005740:Gases / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D012996:Solutions / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet
chemical_list: D004277:DNA, Single-Stranded; D005740:Gases; D012996:Solutions; D004247:DNA