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MO: Fachverband Molekülphysik

MO 2: Biology Related Molecules

MO 2.5: Vortrag

Montag, 5. März 2018, 11:30–11:45, PA 1.150

UV-Induced Self-Repair of a DNA Lesion Traced with Quantum Chemistry — •Daniel Keefer, Vitus Besel, and Regina de Vivie-Riedle — Department of Chemistry, LMU Munich

Nucleobases in DNA and RNA absorb UV light, which can lead to several interesting photophysical and photochemical processes. In a recent experimental study [1], it was revealed that photoexcitation of a guanine (G) adenine (A) sequence can even lead to self-repair of an adjacent cyclobutane pyrimidine dimer (CPD) lesion in oligonucleotides. The proposed mechanism involves photoexcitation of G at 290 nm, followed by a long-living charge transfer state between G and A and subsequent electron donation from the A radical anion to the CPD lesion. This finally induces ring splitting and repair of the damaged nucleobase sequence.

In our theoretical study, we use (multiscale) quantum chemical methods in order to verify this mechanism. The excited states of the GA sequence adjacent to the CPD lesion are computed using high-level active space methods, including explicit consideration of the residual oligonucleotide and the water environment. We will discuss the existance and accessibility of G → A charge transfer states, and trace the time evolution of the experimentally addressed states in the system after photoexcitation by means of semiclassical dynamics.

1  D. Bucher et al. J. Am. Chem. Soc. 2016 138, 186.