Selenium-binding protein 1 (SELENBP1) is a copper-dependent thiol oxidase
Thilo Magnus Philipp1, Leon Gernoth1, Andreas Will1
1Institute of Nutritional Sciences, Nutrigenomics Section, Friedrich Schiller University Jena, Jena, Germany.
Redox Biology
|July 12, 2023
Summary
Copper ions are essential for the methanethiol oxidase (MTO) activity of Selenium-binding protein 1 (SELENBP1). This enzyme degrades volatile sulfur compounds, potentially impacting halitosis.
Area of Science:
- Biochemistry
- Enzymology
- Metalloprotein
Background:
- Selenium-binding protein 1 (SELENBP1) was previously identified as a methanethiol oxidase (MTO).
- SELENBP1 catalyzes the conversion of methanethiol into hydrogen peroxide, hydrogen sulfide, and formaldehyde.
Purpose of the Study:
- To investigate the role of copper ions in SELENBP1's MTO activity.
- To identify novel substrates and understand the physiological relevance of SELENBP1.
Main Methods:
- Site-directed mutagenesis of human SELENBP1 to probe copper-binding sites.
- Enzymatic assays using recombinant SELENBP1.
- Studies on the SELENBP1 ortholog SEMO-1 in *C. elegans*.
Main Results:
- Copper ions were found to be essential for SELENBP1's MTO activity; mutations in putative copper-binding sites abolished function.
- Selenium binding was not required for MTO activity.
- SELENBP1 also metabolizes other volatile sulfur compounds (VSCs) like ethanethiol and 1-pentanethiol.
- *C. elegans* SEMO-1 also requires copper for MTO activity.
Conclusions:
- SELENBP1 is a copper-dependent enzyme crucial for the degradation of methanethiol and other VSCs.
- This copper-dependent VSC degradation by SELENBP1, particularly in tissues like the colon, liver, and lung, may play a role in preventing malodors and extraoral halitosis.
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