Premium
Ultraviolet Absorption Induces Hydrogen‐Atom Transfer in G⋅C Watson–Crick DNA Base Pairs in Solution
Author(s) -
Röttger Katharina,
Marroux Hugo J. B.,
Grubb Michael P.,
Coulter Philip M.,
Böhnke Hendrik,
Henderson Alexander S.,
Galan M. Carmen,
Temps Friedrich,
OrrEwing Andrew J.,
Roberts Gareth M.
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201506940
Subject(s) - molecular structure of nucleic acids: a structure for deoxyribose nucleic acid , ultraviolet , base pair , absorption (acoustics) , chemistry , dna , physics , optics , biochemistry
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⋅C) Watson–Crick base pairs by ultrafast time‐resolved UV/visible and mid‐infrared spectroscopy. The formation of an intermediate biradical species (G[−H]⋅C[+H]) with a lifetime of 2.9 ps was tracked. The majority of these biradicals return to the original G⋅C Watson–Crick pairs, but up to 10 % of the initially excited molecules instead form a stable photoproduct G*⋅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.