Suicide inactivation of covalent peroxidase-mimicking DNAzyme with hydrogen peroxide and its protection by a reductant substrate

• Hydrogen peroxide is an inactivating agent of covalent PMDNAzyme.
• 2,2′-Azino-bis(3-ethylbenthothiazoline-6-sulfonic acid, a reductant substrate prevents cPMDNAzyme inactivation.
• pH-optimum and concentrations of ABTS and H2O2 for the determination of cPMDNAzyme activity were optimized.

Recently a covalent peroxidase-mimicking DNAzyme (cPMDNAzyme) with the improved catalytic activity was prepared. Here we demonstrate that hydrogen peroxide, the oxidant substrate of cPMDNAzyme is an inactivating agent of this catalyst. Presence of the reductant substrate, 2,2′-azino-bis(3-ethylbenthothiazoline-6-sulfonic acid (ABTS) prevents the inactivation of cPMDNAzyme. The experimental conditions (pH-optimum, concentrations of ABTS and H2O2) for the determination of cPMDNAzyme activity were optimized that allows a construction of the colorimetric cPMDNAzyme–based biosensors and assays with improved sensitivity.

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