Detection of 3'→5' exonuclease activity using a metal-based luminescent switch-on probe

Hong Zhang He, Weng I. Chan, Tsun Yin Mak, Li Juan Liu, Modi Wang, Daniel Shiu Hin Chan, Edmond Dik Lung MA*, Chung Hang Leung

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

19 Citations (Scopus)


A luminescent iridium(III) complex has been discovered to be selective for G-quadruplex DNA, and was employed in a label-free G-quadruplex-based detection assay for 3'→5' exonuclease activity in aqueous solution. A proof-of-concept of this assay has been demonstrated by using prokaryotic exonuclease III (ExoIII) as a model enzyme. In this assay, a G-quadruplex-forming hairpin oligonucleotide (hairpin-G4 DNA, 5'-GAG3TG4AG3TG4A2GCAGA2G2ATA2CT2C4AC3TC4AC3TC-3') initially exists in a duplex conformation, resulting in a low luminescence signal due to the weak interaction between the iridium(III) complex and duplex DNA. Upon digestion by ExoIII, the guanine-rich sequence is released and folds into a G-quadruplex, which greatly enhances the luminescence emission of the iridium(III) probe. This method was highly sensitive for 3'→5' exonuclease over other DNA-modifying enzymes.

Original languageEnglish
Pages (from-to)218-223
Number of pages6
Issue number3
Publication statusPublished - 15 Dec 2013

Scopus Subject Areas

  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)

User-Defined Keywords

  • Exonuclease
  • G-quadruplex
  • Iridium
  • Luminescence
  • Metal complex


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