title: Gas-Phase Conformations and N-Glycosidic Bond Stabilities of Sodium Cationized 2'-Deoxyguanosine and Guanosine: Sodium Cations Preferentially Bind to the Guanine Residue.
abstract: 2'-Deoxyguanosine (dGuo) and guanosine (Guo) are fundamental building blocks of DNA and RNA nucleic acids. In order to understand the effects of sodium cationization on the gas-phase conformations and stabilities of dGuo and Guo, infrared multiple photon dissociation (IRMPD) action spectroscopy experiments and complementary electronic structure calculations are performed. The measured IRMPD spectra of [dGuo+Na]+and [Guo+Na]+are compared to calculated IR spectra predicted for the stable low-energy structures computed for these species to determine the most favorable sodium cation binding sites, identify the structures populated in the experiments, and elucidate the influence of the 2'-hydroxyl substituent on the structures and IRMPD spectral features. These results are compared with those from a previous IRMPD study of the protonated guanine nucleosides to elucidate the differences between sodium cationization and protonation on structure. Energy-resolved collision-induced dissociation (ER-CID) experiments and survival yield analyses of protonated and sodium cationized dGuo and Guo are performed to compare the effects of these cations toward activating the N-glycosidic bonds of these nucleosides. For both [dGuo+Na]+and [Guo+Na]+, the gas-phase structures populated in the experiments are found to involve bidentate binding of the sodium cation to the O6 and N7 atoms of guanine, forming a 5-membered chelation ring, with guanine found in both anti and syn orientations and C2'-endo (2T3or3T2) puckering of the sugar. The ER-CID results, IRMPD yields and the computed C1'-N9 bond lengths indicate that sodium cationization activates the N-glycosidic bond less effectively than protonation for both dGuo and Guo. The 2'-hydroxyl substituent of Guo is found to impact the preferred structures very little except that it enables a 2'OH···3'OH hydrogen bond to be formed, and stabilizes the N-glycosidic bond relative to that of dGuo in both the sodium cationized and protonated complexes.
authors.affiliation: Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: L A
authors.identifier: 0000-0002-7988-5117
authors.initials: LA
authors.lastname: Hamlow
authors.affiliation: Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: C C
authors.initials: CC
authors.lastname: He
authors.affiliation: Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: J K
authors.initials: JK
authors.lastname: Lee
authors.affiliation: Institute for Molecules and Materials, FELIX Laboratory, Radboud University , Toernooiveld 7c, 6525ED Nijmegen, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Gao
authors.affiliation: Institute for Molecules and Materials, FELIX Laboratory, Radboud University , Toernooiveld 7c, 6525ED Nijmegen, The Netherlands.
authors.forename: G
authors.initials: G
authors.lastname: Berden
authors.affiliation: Institute for Molecules and Materials, FELIX Laboratory, Radboud University , Toernooiveld 7c, 6525ED Nijmegen, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Oomens
authors.affiliation: Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: M T
authors.identifier: 0000-0002-5614-0948
authors.initials: MT
authors.lastname: Rodgers
mesh_terms: D001665:Binding Sites; D002414:Cations, Monovalent / Q000737:chemistry; D003849:Deoxyguanosine / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry; D006147:Guanine / Q000737:chemistry*; D006151:Guanosine / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D010782:Photolysis; D012964:Sodium / Q000737:chemistry*
chemical_list: D002414:Cations, Monovalent; D006027:Glycosides; D006151:Guanosine; D006147:Guanine; D012964:Sodium; D003849:Deoxyguanosine