Transient Catalytic Voltammetry of Sulfite Oxidase Reveals Rate Limiting Conformational Changes
- Sulfite oxidases are metalloenzymes that oxidize sulfite to sulfate at a molybdenum active site. In vertebrate sulfite oxidases, the electrons generated at the Mo center are transferred to an external electron acceptor via a heme domain, which can adopt two conformations: a “closed” conformation, suitable for internal electron transfer, and an “open” conformation suitable for intermolecular electron transfer. This conformational change is an integral part of the catalytic cycle. Sulfite oxidases have been wired to electrode surfaces, but their immobilization leads to a significant decrease in their catalytic activity, raising the question of the occurrence of the conformational change when the enzyme is on an electrode. We recorded and quantitatively modeled for the first time the transient response of the catalytic cycle of human sulfite oxidase immobilized on an electrode. We show that conformational changes still occur on the electrode, but at a lower rate than in solution, which is the reason for the decrease in activity ofSulfite oxidases are metalloenzymes that oxidize sulfite to sulfate at a molybdenum active site. In vertebrate sulfite oxidases, the electrons generated at the Mo center are transferred to an external electron acceptor via a heme domain, which can adopt two conformations: a “closed” conformation, suitable for internal electron transfer, and an “open” conformation suitable for intermolecular electron transfer. This conformational change is an integral part of the catalytic cycle. Sulfite oxidases have been wired to electrode surfaces, but their immobilization leads to a significant decrease in their catalytic activity, raising the question of the occurrence of the conformational change when the enzyme is on an electrode. We recorded and quantitatively modeled for the first time the transient response of the catalytic cycle of human sulfite oxidase immobilized on an electrode. We show that conformational changes still occur on the electrode, but at a lower rate than in solution, which is the reason for the decrease in activity of sulfite oxidases upon immobilization.…
Author details: | Ting Zeng, Silke LeimkühlerORCiDGND, Ulla WollenbergerORCiDGND, Vincent FourmondORCiD |
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DOI: | https://doi.org/10.1021/jacs.7b05480 |
ISSN: | 0002-7863 |
Pubmed ID: | https://pubmed.ncbi.nlm.nih.gov/28727916 |
Title of parent work (English): | Journal of the American Chemical Society |
Publisher: | American Chemical Society |
Place of publishing: | Washington |
Publication type: | Article |
Language: | English |
Year of first publication: | 2017 |
Publication year: | 2017 |
Release date: | 2020/04/20 |
Volume: | 139 |
Number of pages: | 9 |
First page: | 11559 |
Last Page: | 11567 |
Funding institution: | CNRS; Agence Nationale de la Recherche [ANR-12-BS08-0014, Government program [ANR-11-IDEX-0001-02]; Deutsche Forschungsgemeinschaft (Unicat Cluster of Excellence) [EXC 314] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Biochemie und Biologie |
Peer review: | Referiert |