Comprehensive Study of Guanine Excited State Relaxation and Photoreactivity in G-quadruplexes(136 views) Martinez-fernandez L, Changenet P, Banyasz A, Gustavsson T, Markovitsi D, Improta R
J Phys Chem Lett (ISSN: 1948-7185linking, 1948-7185electronic), 2019 Nov 7; 10(21): 6873-6877.
LIDYL, CEA, CNRS, Universite Paris-Saclay , F-91191 Gif-sur-Yvette , France., Laboratoire d'Optique et Biosciences, Institut Polytechnique de Paris , CNRS, INSERM, Universite Paris-Saclay , 91128 Palaiseau cedex , France., Istituto Biostrutture e Bioimmagini-Consiglio Nazionale delle Ricerche , Via Mezzocannone 16 , I-80134 Napoli , Italy.,
References: Not available.
Comprehensive Study of Guanine Excited State Relaxation and Photoreactivity in G-quadruplexes
G-quadruplexes (G4) are four-stranded DNA/RNA structures playing a key role in many biological functions and promising for nanotechnology applications. Here, combining theoretical calculations and multiscale time-resolved fluorescence, we describe, for the first time, an ensemble of photoactivated processes involving the guanines of the G4 core. We use as showcase the G4 formed by the human telomeric sequence GGG(TTAGGG)3 in the presence of Na(+) ions. According to quantum mechanical/molecular mechanics calculations, the hyperchromism at the red part of the absorption spectrum, typical of G4 structures, arises mainly from the inner Na(+) ions. Various relaxation pathways, leading to excited states localized on individual bases, neutral excimers, and excited charge transfer states between two guanines or a guanine and a thymine in the loop, are mapped. Their fingerprints are detected in the fluorescence anisotropies and the fluorescence decays, spanning five decades of time. Finally, a reaction funnel leading to guanine dimerization is identified.
Comprehensive Study of Guanine Excited State Relaxation and Photoreactivity in G-quadruplexes