Catalytic electrochemistry of xanthine dehydrogenase
- We report the mediated electrocatalytic voltammetry of the molybdoenzyme xanthine dehydrogenase (XDH) from Rhodobacter capsulatus at a thiol-modified Au electrode. The 2-electron acceptor N-methylphenazinium methanesulfonate (phenazine methosulfate, PMS) is an effective artificial electron transfer partner for XDH instead of its native electron acceptor NAD(+). XDH catalyzes the oxidative hydroxylation of hypoxanthine to xanthine and xanthine to uric acid. Cyclic voltammetry was used to generate the active (oxidized) form of the mediator. Simulation of the catalytic voltammetry across a broad range of substrate and PMS concentrations at different sweep rates was achieved with the program DigiSim to yield a set of consistent rate and equilibrium constants that describe the catalytic system. This provides the first example of the mediated electrochemistry of a xanthine dehydrogenase (or oxidase) that is uncomplicated by interference from product oxidation. A remarkable two-step, sequential oxidation of hypoxanthine to uric acid viaWe report the mediated electrocatalytic voltammetry of the molybdoenzyme xanthine dehydrogenase (XDH) from Rhodobacter capsulatus at a thiol-modified Au electrode. The 2-electron acceptor N-methylphenazinium methanesulfonate (phenazine methosulfate, PMS) is an effective artificial electron transfer partner for XDH instead of its native electron acceptor NAD(+). XDH catalyzes the oxidative hydroxylation of hypoxanthine to xanthine and xanthine to uric acid. Cyclic voltammetry was used to generate the active (oxidized) form of the mediator. Simulation of the catalytic voltammetry across a broad range of substrate and PMS concentrations at different sweep rates was achieved with the program DigiSim to yield a set of consistent rate and equilibrium constants that describe the catalytic system. This provides the first example of the mediated electrochemistry of a xanthine dehydrogenase (or oxidase) that is uncomplicated by interference from product oxidation. A remarkable two-step, sequential oxidation of hypoxanthine to uric acid via xanthine by XDH is observed.…
| Author details: | Palraj Kalimuthu, Silke LeimkühlerORCiDGND, Paul V. Bernhardt |
|---|---|
| DOI: | https://doi.org/10.1021/jp307374z |
| ISSN: | 1520-6106 |
| Title of parent work (English): | The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry |
| Publisher: | American Chemical Society |
| Place of publishing: | Washington |
| Publication type: | Article |
| Language: | English |
| Year of first publication: | 2012 |
| Publication year: | 2012 |
| Release date: | 2017/03/26 |
| Volume: | 116 |
| Issue: | 38 |
| Number of pages: | 8 |
| First page: | 11600 |
| Last Page: | 11607 |
| Funding institution: | Australian Research Council [DP0880288, DP120101465]; Deutsche Forschungsgemeinschaft Cluster of Excellence "Unifying concepts in catalysis" |
| Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Biochemie und Biologie |
| Peer review: | Referiert |
