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Proposing Institution

Theoretische Chemie, LMU
Project Manager

Sebastian Reiter
Butenandtstr. 5 - 13
81377 München
Ultraviolet radiation can induce photochemical reactions in nucleic acids and is therefore one of the major risk factors for damage to the genetic code. Nevertheless, the majority of photoexcitations in RNA and DNA do not lead to harmful reactions as the excess energy is dissipated via ultrafast, non-radiative relaxation pathways exhibited by all five canonical nucleobases. These processes are extensively investigated both experimentally and theoretically, mostly for isolated nucleobases. Our research focuses on the dynamics of the RNA base uracil after photoexcitation. We recently published wave packet simulations of this process in gas phase uracil, which lead to new insights into the underlying mechanisms of photostability as well as the first step towards photodamage.The next goal would be to go beyond gas phase calculations and consider uracil in its native biological environment. Here, the sugar phosphate backbone as well as neighbouring nucleobases and solvent molecules might influence the ultrafast population decay and therefore the photostability. Aiming for an explicit description of the environment, it is necessary to simulate the relaxation process in many different environmental snapshots, which we extract from classical molecular dynamics (MD) simulations. The 2D potential energy surface describing the relaxation process needs to be recalculated for every MD snapshot. Using quantum mechanics/molecular mechanics (QM/MM) calculations with QM regions of up to 1000 atoms, this is a computationally demanding task we would like to carry out on the SuperMUC system. We can then use the obtained surfaces to run wave packet dynamics in order to elucidate the effects of different neighbouring nucleobases and the biological environment on the photostability of uracil by comparing excited state lifetimes after UV irradiation.

Impressum, Conny Wendler