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Updated: Mar 13, 2026

Author Spotlight: Characterizing DNA G-Quadruplex by Bis-3-Chloropiperidine Based Chemical Mapping
Published on: May 12, 2023
Binding of the alkaloid coralyne to parallel G-quadruplex DNA [d(TTGGGGT)]4 studied by multi-spectroscopic techniques
Kumar Padmapriya1, Ritu Barthwal1
1Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India.
Abstract:
Binding of coralyne to tetra-molecular parallel G-quadruplex DNA [d(TTGGGGT)]4 was evaluated for the first time using biophysical techniques. Absorbance titrations show hypo/hyper-chromism accompanied by 12nm red shift with binding constant Kb=0.2-4.0×106M-1. Binding induces a negative circular dichroism band of coralyne at 315nm. Quenching of fluorescence (~64%) along with 10nm blue shift in emission maxima indicates proximity of coralyne to guanine bases. Job plot indicates existence of multiple complexes. The observed two fluorescence life times, 6 and 12ns, with relative abundance 33% and 63%, respectively suggest two binding sites/conformations in complex. 1D 1H NMR spectra reveal significant broadening and upfield shift of G3NH, G6NH and G3H8 proton signals upon binding. The NOESY spectra reveal sequence specific non-intercalative interaction of coralyne in monomeric form at two sites close to A3/G3 and G6 bases of [d(TTGGGGT)]4 and [d(TTAGGGT)]4, which has implications in anti-cancer drug action.
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