title: Characterization of G-quadruplex/hemin peroxidase: substrate specificity and inactivation kinetics.
abstract: Recently, G-quadruplex/hemin (G4/hemin) complexes have been found to exhibit peroxidase activity, and this feature has been extensively exploited for colorimetric detection of various targets. To further understand and characterize this important DNAzyme, its substrate specificity, inactivation mechanism, and kinetics have been examined by comparison with horseradish peroxidase (HRP). G4/hemin DNAzyme exhibits broader substrate specificity and much higher inactivation rate than HRP because of the exposure of the catalytic hemin center. The inactivation of G4/hemin DNAzyme is mainly attributed to the degradation of hemin by H(2)O(2) rather than the destruction of G4. Both the inactivation rate and catalytic oxidation rate of G4/hemin DNAzyme depend on the concentration of H(2)O(2), which suggests that active intermediates formed by G4/hemin and H(2)O(2) are the branch point of catalysis and inactivation. Reducing substrates greatly inhibit the inactivation of G4/hemin DNAzyme by rapidly reacting with the active intermediates. A possible catalytic and inactivation process of G4/hemin has been proposed. These results imply a potential cause for the hemin-mediated cellular injury and provide insightful information for the future application of G4/hemin DNAzyme.
authors: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing, 100190, PR China.
authors: Xiaojuan
authors: X
authors: Yang
authors: Canliang
authors: C
authors: Fang
authors: Hongcheng
authors: H
authors: Mei
authors: Tianjun
authors: T
authors: Chang
authors: Zehui
authors: Z
authors: Cao
authors: Dihua
authors: D
authors: Shangguan
mesh_terms: D002384:Catalysis; D003124:Colorimetry; D021881:DNA, Catalytic / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D054856:G-Quadruplexes; D006427:Hemin / Q000737:chemistry / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000032:analysis; D007700:Kinetics; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013379:Substrate Specificity
chemical_list: D021881:DNA, Catalytic; D006427:Hemin; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D009195:Peroxidase