Roettger, Katharina, Marroux, Hugo J. B., Grubb, Michael P., Coulter, Philip M., Boehnke, Hendrik, Henderson, Alexander S., Galan, M. Carmen, Temps, Friedrich, Orr-Ewing, Andrew J. and Roberts, Gareth M. (2015) Ultraviolet Absorption Induces Hydrogen-Atom Transfer in G center dot C Watson-Crick DNA Base Pairs in Solution. Angewandte Chemie-International Edition, 54 (49). pp. 14719-14722.

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Abstract

Ultrafast deactivation pathways bestow photostability on nucleobases and hence preserve the structural integrity of DNA following absorption of ultraviolet (UV) radiation. One controversial recovery mechanism proposed to account for this photostability involves electron-driven proton transfer (EDPT) in Watson-Crick base pairs. The first direct observation is reported of the EDPT process after UV excitation of individual guanine-cytosine (G center dot C) Watson-Crick base pairs by ultrafast time-resolved UV/visible and mid-infrared spectroscopy. The formation of an intermediate biradical species (G[-H]center dot C[+H]) with a lifetime of 2.9 ps was tracked. The majority of these biradicals return to the original G center dot C Watson-Crick pairs, but up to 10% of the initially excited molecules instead form a stable photoproduct G*center dot C* that has undergone double hydrogen-atom transfer. The observation of these sequential EDPT mechanisms across intermolecular hydrogen bonds confirms an important and long debated pathway for the deactivation of photoexcited base pairs, with possible implications for the UV photochemistry of DNA.

Document Type:	Article
Additional Information:	Times Cited: 0
Research affiliation:	Kiel University OceanRep > The Future Ocean - Cluster of Excellence
Projects:	Future Ocean
Date Deposited:	18 Oct 2016 03:46
Last Modified:	18 Oct 2016 03:46
URI:	https://oceanrep.geomar.de/id/eprint/32662

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