title: Base pairing enhances fluorescence and favors cyclobutane dimer formation induced upon absorption of UVA radiation by DNA.
abstract: The photochemical properties of the DNA duplex (dA)(20)·(dT)(20) are compared with those of the parent single strands. It is shown that base pairing increases the probability of absorbing UVA photons, probably due to the formation of charge-transfer states. UVA excitation induces fluorescence peaking at ∼420 nm and decaying on the nanosecond time scale. The fluorescence quantum yield, the fluorescence lifetime, and the quantum yield for cyclobutane dimer formation increase upon base pairing. Such behavior contrasts with that of the UVC-induced processes.
authors.affiliation: CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, 91191 Gif-sur-Yvette, France.
authors.forename: Akos
authors.initials: A
authors.lastname: Banyasz
authors.forename: Ignacio
authors.initials: I
authors.lastname: Vayá
authors.forename: Pascale
authors.initials: P
authors.lastname: Changenet-Barret
authors.forename: Thomas
authors.initials: T
authors.lastname: Gustavsson
authors.forename: Thierry
authors.initials: T
authors.lastname: Douki
authors.forename: Dimitra
authors.initials: D
authors.lastname: Markovitsi
mesh_terms: D000042:Absorption; D020029:Base Pairing / Q000528:radiation effects*; D003503:Cyclobutanes / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D019281:Dimerization; D011740:Pyrimidine Dimers / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D014466:Ultraviolet Rays
chemical_list: D003503:Cyclobutanes; D011740:Pyrimidine Dimers; D004247:DNA