Peroxidase activity of the Pu39WT-hemin complex. The Pu39WT parallel G-quadruplex-hemin complex has a peroxidase activity. (A) Comparison of DNAzyme activities of experiments carried out with Pu39WT (0.5 μM), hemin (0.5 μM), H2O2 (0.6 mM), and ABTS (6 mM) in the presence of either K+ or Na+. The oxidation of ABTS was monitored over 10 min. (B) Catalytic kinetics of the Pu39WT-hemin complex at different substrate (ABTS) concentrations, with Pu39WT (0.5 μM), hemin (0.5 μM), H2O2 (0.6 mM) and ABTS (from 6 mM to 18 mM). UV–Vis absorbance versus time plots at different substrate concentrations: 6, 9, 12, 15, 18 mM, corresponding to ABTS-1 to 5, respectively; Photograph of visible oxidation of ABTS corresponding to Figure B, taken 40 min after the reaction was triggered.