title: The anionic (9-methyladenine)-(1-methylthymine) base pair solvated by formic acid. A computational and photoelectron spectroscopy study.
abstract: The photoelectron spectrum for (1-methylthymine)-(9-methyladenine)...(formic acid) (1MT-9MA...FA) anions with the maximum at ca. 1.87 eV was recorded with 2.54 eV photons and interpreted through the quantum-chemical modeling carried out at the B3LYP/6-31+G(d,p) level. The relative free energies of the anions and their calculated vertical detachment energies suggest that only seven anionic structures contribute to the observed PES signal. We demonstrate that electron binding to the (1MT-9MA...FA) complex can trigger intermolecular proton transfer from formic acid, leading to the strong stabilization of the resulting radical anion. The SOMO distribution indicates that an excess electron may localize not only on the pyrimidine but also on the purine moiety. The biological context of DNA-environment interactions concerning the formation of single-strand breaks induced by excess electrons has been briefly discussed.
authors.affiliation: Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland. pondros@chem.univ.gda.pl
authors.forename: Piotr
authors.initials: P
authors.lastname: Storoniak
authors.forename: Kamil
authors.initials: K
authors.lastname: Mazurkiewicz
authors.forename: Maciej
authors.initials: M
authors.lastname: Haranczyk
authors.forename: Maciej
authors.initials: M
authors.lastname: Gutowski
authors.forename: Janusz
authors.initials: J
authors.lastname: Rak
authors.forename: Soren N
authors.initials: SN
authors.lastname: Eustis
authors.forename: Yeon Jae
authors.initials: YJ
authors.lastname: Ko
authors.forename: Haopeng
authors.initials: H
authors.lastname: Wang
authors.forename: Kit H
authors.initials: KH
authors.lastname: Bowen
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000737:chemistry; D000838:Anions / Q000737:chemistry; D020029:Base Pairing; D005561:Formates / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry; D013816:Thermodynamics; D013941:Thymine / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D000838:Anions; D005561:Formates; D012997:Solvents; C030544:formic acid; C030630:1-methylthymine; C013115:9-methyladenine; D000225:Adenine; D013941:Thymine