title: The intrinsic stabilities and structures of alkali metal cationized guanine quadruplexes.
abstract: The structures and stabilities of self-assembled guanine quadruplexes, M(9eG)8+(M = Na, K, Rb, Cs; 9eG = 9-ethylguanine), have been studied in the gas phase by blackbody infrared radiative dissociation to determine the difference in the stabilizing effect of the alkali metal cations. The order of stabilities to decomposition was determined to be K+> Rb+> Cs+≫ Na+, which is consistent with the observation of K+being the ion of choice in guanine quadruplexes in nucleic acids. In the gas phase, the sodiated quadruplex was found to lose one 9eG at a time, whereas the quadruplexes of the heavier cations lost a neutral guanine tetrad. Vibrational spectroscopy on the gas-phase quadruplex ions was consistent with the structures in which the metal cations were sandwiched between two guanine tetrads. Electronic structure calculations are also used to compare with the observed stabilities and vibrational spectra.
authors.affiliation: Department of Chemistry, Memorial University, St John's, NL A1B 3X7, Canada. tfridgen@mun.ca.
authors.forename: M
authors.initials: M
authors.lastname: Azargun
authors.affiliation: Department of Chemistry, Memorial University, St John's, NL A1B 3X7, Canada. tfridgen@mun.ca.
authors.forename: Y
authors.initials: Y
authors.lastname: Jami-Alahmadi
authors.affiliation: Department of Chemistry, Memorial University, St John's, NL A1B 3X7, Canada. tfridgen@mun.ca.
authors.forename: T D
authors.initials: TD
authors.lastname: Fridgen
mesh_terms: D002412:Cations / Q000737:chemistry; D054856:G-Quadruplexes; D008672:Metals, Alkali / Q000737:chemistry*; D008958:Models, Molecular
chemical_list: D002412:Cations; D008672:Metals, Alkali