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Topology Controls the Electronic Absorption and Delocalization of Electron Holes in Guanine Quadruplexes
Author(s) -
MartínezFernández Lara,
Banyasz Akos,
Markovitsi Dimitra,
Improta Roberto
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201803222
Subject(s) - delocalized electron , guanine , antiparallel (mathematics) , topology (electrical circuits) , absorption spectroscopy , absorption (acoustics) , electron , chemical physics , chemistry , ionization , materials science , crystallography , physics , ion , quantum mechanics , gene , mathematics , organic chemistry , combinatorics , magnetic field , composite material , nucleotide , biochemistry
Guanine quadruplexes ( G4 ) are four‐stranded DNA structures involved in biological processes and are promising candidates for potential nanotechnological applications. This study examines how the G4 topology affects the electronic absorption and the delocalization of electron holes, which play a key role in charge transport and oxidative damage. Combining transient absorption spectroscopy with PCM/TD‐DFT calculations both parallel ( P ) and antiparallel ( A ) G4 are investigated, which are formed, respectively, by association of four TGGGGT strands and folding of the human telomeric sequence GGG(TTAGGG) 3 . The experimental absorption spectra obtained upon photo‐ionization of A and P are different. This is explained by the different topology of the two G4 , as well as by hole delocalization between two stacked guanines, possible only in P + . The spectral signature of delocalized hole in guanine‐rich regions is provided and the chemical physical effects which rule the hole delocalization are discussed.