Extended Data Fig. 2: Photophysical characterization of 9 and its interactions with G4 DNA.
From: Optical control of gene expression using a DNA G-quadruplex targeting reversible photoswitch
a-c, UV-Vis absorption spectra of 50 μM 9 in PBS, measured (a) in the dark, after 405 nm illumination for 2 min and subsequent 525 nm illumination for 2 min, and (b,c) after a series of 405 nm and 525 nm illumination durations (0-300 s), starting from the steady dark-adapted state and 405 nm illuminated state, respectively. d, UV-Vis absorbance of 50 μM 9 at 475 nm in PBS, measured during consecutive cis-trans photoisomerization cycles, alternating between 405 nm and 525 nm illuminations. e,f, Thermal trans-to-cis relaxation of 50 μM 9 in PBS, with half-lives of (e) t1/2 = 11.2 h at 25 °C and (f) t1/2 = 2.6 h at 37 °C, measured by recording UV-Vis absorbance of trans-9 at 470 nm and 475 nm, respectively. g, CD spectra of G4 MYC recorded by a titration with increasing amounts of 9 in 10 mM Tris-HCl buffer, 100 mM LiCl, pH 7.4 after further 525 nm illumination for 60 s of the 405 nm illuminated samples shown in Fig. 3e.
