Thiazole Orange: A Useful Probe for Fluorescence Sensing of G-Quadruplex–Ligand Interactions

Abstract

Fluorimetric titrations were performed to gain insight into parameters that govern the association of thiazole orange (TO) and G-quadruplex-DNA (G4-DNA). Use of loop-containing and loop- lacking quadruplexes evidenced the critical influence of the loops on the stoichiometry of the association and on the fluorescence exaltation of TO. We subsequently tried to benefit from this sensitivity to evaluate the influence of G4-DNA cationic environment on ligand binding via a recently reported G4-FID assay.

Keywords:

• Thiazole orange
• G-quadruplex-DNA
• fluorescent probe

This work was supported by Centre National de la Recherche Scientifique (CNRS) and Commissariat à l'Energie Atomique (CEA). We also acknowledge C. Hounsou for the syntheses of quinacridine ligands and Dr. S. Bombard, A. DeCian and Dr J.-L. Mergny for helpful scientific discussions.