title: Detection of 3'→5' exonuclease activity using a metal-based luminescent switch-on probe.
abstract: 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.
authors: Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
authors: Hong-Zhang
authors: HZ
authors: He
authors: Weng-I
authors: WI
authors: Chan
authors: Tsun-Yin
authors: TY
authors: Mak
authors: Li-Juan
authors: LJ
authors: Liu
authors: Modi
authors: M
authors: Wang
authors: Daniel Shiu-Hin
authors: DS
authors: Chan
authors: Dik-Lung
authors: DL
authors: Ma
authors: Chung-Hang
authors: CH
authors: Leung
mesh_terms: D055162:Biocatalysis; D015374:Biosensing Techniques; D056831:Coordination Complexes / Q000737:chemistry; D015342:DNA Probes / Q000737:chemistry; D005090:Exodeoxyribonucleases / Q000737:chemistry*; D054856:G-Quadruplexes; D055029:Inverted Repeat Sequences; D007495:Iridium / Q000737:chemistry; D049408:Luminescent Agents / Q000737:chemistry
chemical_list: D056831:Coordination Complexes; D015342:DNA Probes; D049408:Luminescent Agents; D007495:Iridium; D005090:Exodeoxyribonucleases
keywords: BSA; ExoIII; Exonuclease; G-quadruplex; Iridium; Luminescence; Metal complex; T4 PNK; T4 polynucleotide kinase; T7 Exo; T7 exonuclease; UDG; bovine serum albumin; calf-thymus DNA; ctDNA; double-stranded DNA; dsDNA; exonuclease III; lambda exonuclease; single-stranded DNA; ssDNA; uracil-DNA glycosylase; λ Exo