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NMR solution structure of the 1:1 complex of wttel26 g-quadruplex and a tripodal cationic fluorescent probe nbte
Liu LY, Liu W, Wang KN, Zhu BC, Xia XY, Ji LN, Mao ZW (2020): "Quantitative Detection of G-Quadruplex DNA in Live Cells Based on Photon Counts and Complex Structure Discrimination." Angew.Chem.Int.Ed.Engl., 59, 9719-9726. doi: 10.1002/anie.202002422.
G-quadruplex DNA show structural polymorphism, leading to challenges in the use of selective recognition probes for the accurate detection of G-quadruplexes in vivo. Herein, we present a tripodal cationic fluorescent probe, NBTE, which showed distinguishable fluorescence lifetime responses between G-quadruplexes and other DNA topologies, and fluorescence quantum yield (Φf ) enhancement upon G-quadruplex binding. We determined two NBTE-G-quadruplex complex structures with high Φf values by NMR spectroscopy. The structures indicated NBTE interacted with G-quadruplexes using three arms through π-π stacking, differing from that with duplex DNA using two arms, which rationalized the higher Φf values and lifetime response of NBTE upon G-quadruplex binding. Based on photon counts of FLIM, we detected the percentage of G-quadruplex DNA in live cells with NBTE and found G-quadruplex DNA content in cancer cells is 4-fold that in normal cells, suggesting the potential applications of this probe in cancer cell detection.

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