title: Ab initio study of the structural, tautomeric, pairing, and electronic properties of seleno-derivatives of thymine.
abstract: The structural, tautomeric, hydrogen-bonding, stacking, and electronic properties of a seleno-derivative of thymine (T), denoted here as 4SeT and created by replacing O4 in T with Se, are investigated by means of ab initio computational techniques. The structural properties of T and 4SeT are very similar, and the geometrical differences are mainly limited to the adjacent environment of the C-Se bond. The canonical "keto" form is the most stable tautomer, in the gas phase and in aqueous solution, for both T and 4SeT. It is argued that the competition between two opposite trends, i.e., a decrease in the base-pairing ability and an increase of the stacking interaction upon incorporation of 4SeT into a duplex, likely explains the similar experimental melting points of a seleno-derivative duplex (Se-DNA) and its native counterpart. Interestingly, the underlying electronic structure shows that replacement of O4 with Se promotes a reduction in the HOMO-LUMO gap and an increase in interplane coupling, which suggests that Se-DNA could be potentially useful for nanodevice applications. This finding is further supported by the fact that transfer integrals between 4SeT...A stacked base pairs are larger than those determined for similarly stacked natural T...A pairs.
authors.affiliation: Chemistry Department, University of Tennessee, 1416 Circle Drive, 552 Dabney-Buehler Hall, Knoxville, Tennessee 37996-1600, USA. avazque1@utk.edu
authors.forename: Alvaro
authors.initials: A
authors.lastname: Vázquez-Mayagoitia
authors.forename: Oscar
authors.initials: O
authors.lastname: Huertas
authors.forename: Giorgia
authors.initials: G
authors.lastname: Brancolini
authors.forename: Agostino
authors.initials: A
authors.lastname: Migliore
authors.forename: Bobby G
authors.initials: BG
authors.lastname: Sumpter
authors.forename: Modesto
authors.initials: M
authors.lastname: Orozco
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Luque
authors.forename: Rosa
authors.initials: R
authors.lastname: Di Felice
authors.forename: Miguel
authors.initials: M
authors.lastname: Fuentes-Cabrera
mesh_terms: D020029:Base Pairing; D006860:Hydrogen Bonding; D008968:Molecular Conformation; D012643:Selenium / Q000737:chemistry*; D055672:Static Electricity; D013816:Thermodynamics; D013941:Thymine / Q000737:chemistry
chemical_list: D012643:Selenium; D013941:Thymine