Issue 1, 2013

A novel DNAzyme-based colorimetric assay for the detection of hOGG1 activity with lambda exonuclease cleavage

Abstract

The generation of 8-oxo-7,8-dihydroguanine (8-oxoG) in DNA is a common type of DNA damage after exposure to reactive oxygen species or drugs. Human 8-oxoG DNA glycosylase/AP lyase (hOGG1) is a kind of base excision repair enzyme specifically used to repair the base excision of 8-oxoG. In this paper, we develop a novel, simple and sensitive strategy for the detection of hOGG1 activity based on the self-assembly of the active HRP-mimicking DNAzyme coupled with lambda exonuclease (λ exo) cleavage. We designed two DNA oligonucleotides that are fully complementary to each other. One is modified with 8-oxoG, the other contains the G-quadruplex DNAzyme sequence. The two single-stranded DNA (ssDNA) firstly hybridize to form a DNA duplex containing an 8-oxoG. In the presence of hOGG1, the formed DNA duplex is selectively cleaved at the 8-oxoG site, yielding a new DNA duplex with a recessed 5′-phosphate terminus. Upon treatment with λ exo, the 5′-phosphoryl ssDNA of the new DNA duplex is digested by λ exo, releasing the G-quadruplex DNAzyme sequence. After addition of hemin, the G-quadruplex–hemin complex is used as a peroxidase-mimicking DNAzyme, catalyzing H2O2-mediated oxidation of 2,2′-azinobis(3-ethylbenzothiozoline)-6-sulfonic acid (ABTS2−) to generate a colorimetric signal. The activity of hOGG1 is directly related to UV/Vis absorption intensity. The results revealed that the method allowed a sensitive quantitative assay of the hOGG1 concentration with a wide range from 0.05–32 U mL−1 and a low detection limit of 0.01 U mL−1.

Graphical abstract: A novel DNAzyme-based colorimetric assay for the detection of hOGG1 activity with lambda exonuclease cleavage

Article information

Article type
Paper
Submitted
10 Sep 2012
Accepted
18 Oct 2012
First published
23 Oct 2012

Anal. Methods, 2013,5, 164-168

A novel DNAzyme-based colorimetric assay for the detection of hOGG1 activity with lambda exonuclease cleavage

S. Liu, H. Wu, J. Jiang, G. Shen and R. Yu, Anal. Methods, 2013, 5, 164 DOI: 10.1039/C2AY26018B

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