title: Determination of the electron-detachment energies of 2'-deoxyguanosine 5'-monophosphate anion: influence of the conformation.
abstract: The vertical electron-detachment energies (VDEs) of the singly charged 2'-deoxyguanosine 5'-monophosphate anion (dGMP-) are determined by using the multiconfigurational second-order perturbation CASPT2 method at the MP2 ground-state equilibrium geometry of relevant conformers. The origin of the unique low-energy band in the gas phase photoelectron spectrum of dGMP-, with maximum at around 5.05 eV, is unambiguously assigned to electron detachment from the highest occupied molecular orbital of pi-character belonging to guanine fragment of a syn conformation. The presence of a short H-bond linking the 2-amino and phosphate groups, the guanine moiety acting as proton donor, is precisely responsible for the pronounced decrease of the computed VDE with respect to that obtained in other conformations. As a whole, the present research supports the nucleobase as the site with the lowest ionization potential in negatively charged (deprotonated) nucleotides at the most stable conformations as well as for B-DNA-like type arrangements, in agreement with experimental evidence.
authors.affiliation: Instituto de Ciencia Molecular, Universitat de València, Apartado 22085, ES-46071 Valencia, Spain. Mercedes.Rubio@uv.es
authors.forename: Mercedes
authors.initials: M
authors.lastname: Rubio
authors.forename: Daniel
authors.initials: D
authors.lastname: Roca-Sanjuán
authors.forename: Luis
authors.initials: L
authors.lastname: Serrano-Andrés
authors.forename: Manuela
authors.initials: M
authors.lastname: Merchán
mesh_terms: D003848:Deoxyguanine Nucleotides / Q000737:chemistry*; D004583:Electrons; D008968:Molecular Conformation; D013816:Thermodynamics
chemical_list: D003848:Deoxyguanine Nucleotides; C007257:2'-deoxyguanosine 5'-phosphate