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Base Pairing Enhances Fluorescence and Favors Cyclobutane Dimer Formation Induced upon Absorption of UVA Radiation by DNA

2011; American Chemical Society; Volume: 133; Issue: 14 Linguagem: Inglês

10.1021/ja110879m

1943-2984

Ákos Bányász, Ignacio Vayá, Pascale Changenet‐Barret, T. Gustavsson, Thierry Douki, Dimitra Markovitsi,

Photochemistry and Electron Transfer Studies

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.