Simple and Convenient G-Quadruplex-Based Turn-On Fluorescence Assay for 3′ → 5′ Exonuclease Activity

A selective, oligonucleotide-based, label-free, turn-on fluorescence detection method for 3' -> 5' exonuclease activity has been developed using crystal violet as a G-quadruplex-binding probe. The assay is highly simple and rapid, does not require the use of gel-based equipment or radioisotopic labeling, and is amenable to high-throughput and real-time detection. A proof-of-concept of this assay has been demonstrated for prokaryotic Exonuclease HI (ExoIII) and human TREX1.