title: Absorption spectrum of A-T DNA unraveled by quantum mechanical calculations in solution on the (dA)2 x (dT)2 tetramer.
abstract: The absorption spectrum of A-T DNA is computed for the first time in aqueous solution by means of quantum mechanical calculations performed on realistic models, thereby accounting for both stacking and base pairing interactions and including solvent effects through the polarizable continuum model. The computed and experimental spectra are in close agreement. Our analysis allows the identification of all the electronic transitions hidden in the broad absorption spectrum of A-T DNA, thus determining their most relevant properties and providing an explanation for the most significant experimental features, such as the small blue shift of the band maximum and the appearance of a shoulder on the red wing of the absorption band. The lowest-energy dark excited state corresponds to a charge-transfer state between two stacked adenine bases.
authors.affiliation: Istituto per i Processi Chimico-Fisici-CNR, Area della Ricerca del CNR Via Moruzzi,1 I-56124 Pisa, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Santoro
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Barone
authors.forename: Roberto
authors.initials: R
authors.lastname: Improta
mesh_terms: D054856:G-Quadruplexes; D008956:Models, Chemical; D011067:Poly dA-dT / Q000737:chemistry*; D011789:Quantum Theory; D012996:Solutions; D013057:Spectrum Analysis
chemical_list: D012996:Solutions; D011067:Poly dA-dT