A Photoreactive G-Quadruplex Ligand Triggered by Green Light

A photoreactive molecular dye targeting the G-​quadruplex nucleic acid (G4) of the human telomeric sequence Tel22, and several mutated analogs, was activated by green light (λ=532 nm)​. Highly selective covalent modification of G4 vs. single-​stranded and double-​stranded DNA was achieved with efficiency up to 64 %. The phenoxyl radical was generated and detected by laser-​flash photolysis as a reactive intermediate that targeted loop thymine residues. These insights may suggest a non-​invasive tool for selective nucleic acid tagging and "pull-​down" cellular applications.