A heme•DNAzyme activated by hydrogen peroxide catalytically oxidizes thioethers by direct oxygen atom transfer rather than by a Compound I-like intermediate
| Autor: | Jeffrey J. Warren, Nisreen Shumayrikh, Dipankar Sen, Andrew J. Bennet |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
AcademicSubjects/SCI00010
Deoxyribozyme Thiophenes Biology Sulfides 010402 general chemistry 01 natural sciences Catalysis 03 medical and health sciences chemistry.chemical_compound Thioether Chemical Biology and Nucleic Acid Chemistry Genetics Heme 030304 developmental biology 0303 health sciences Electron Spin Resonance Spectroscopy Substrate (chemistry) DNA Catalytic Hydrogen Peroxide Combinatorial chemistry 0104 chemical sciences G-Quadruplexes Oxygen Kinetics chemistry Catalytic cycle Biocatalysis Hemin |
| Zdroj: | Nucleic Acids Research |
| ISSN: | 1362-4962 0305-1048 |
| Popis: | Hemin [Fe(III)-protoporphyrin IX] is known to bind tightly to single-stranded DNA and RNA molecules that fold into G-quadruplexes (GQ). Such complexes are strongly activated for oxidative catalysis. These heme•DNAzymes and ribozymes have found broad utility in bioanalytical and medicinal chemistry and have also been shown to occur within living cells. However, how a GQ is able to activate hemin is poorly understood. Herein, we report fast kinetic measurements (using stopped-flow UV–vis spectrophotometry) to identify the H2O2-generated activated heme species within a heme•DNAzyme that is active for the oxidation of a thioether substrate, dibenzothiophene (DBT). Singular value decomposition and global fitting analysis was used to analyze the kinetic data, with the results being consistent with the heme•DNAzyme's DBT oxidation being catalyzed by the initial Fe(III)heme–H2O2 complex. Such a complex has been predicted computationally to be a powerful oxidant for thioether substrates. In the heme•DNAzyme, the DNA GQ enhances both the kinetics of formation of the active intermediate as well as the oxidation step of DBT by the active intermediate. We show, using both stopped flow spectrophotometry and EPR measurements, that a classic Compound I is not observable during the catalytic cycle for thioether sulfoxidation. |
| Databáze: | OpenAIRE |
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