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 analogues, was activated by green light (λ=532 nm). Highly selective covalent modification of G4 versus 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. Given the green light: Activation of a photoreactive molecular dye by green light (λ=532 nm) has been shown to generate selective and efficient (64 %) covalent targeting of human telomeric DNA and mutated analogues (see scheme).