Probing the Structure and Dynamics of Telomeric G-Quadruplexes with Thienoguanosine, a Fluorescent Analogue of Guanosine

G serves as a remarkably sensitive, minimally perturbing fluorescent guanosine analogue for structural and dynamic studies of G4s. Moreover, its longest lifetime (18.5 to 28.5 ns), at least twice that in DNA duplexes, is suitable for time-gated detection with high signal-to-noise ratio and easy distinction of G4s from duplexes, offering a key advantage for G4-targeting drug discovery.