flavin-dependent sulfhydryl oxidase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: [protein]-dithiol + O2 = [protein]-disulfide + H2O2 using FAD as a cofactor, leading to formation of disulfide bridges in proteins. [PMID:10899311, PMID:19679655, PMID:35495482]

Flavin-dependent sulfhydryl oxidase activity is a critical enzyme function involved in the oxidation of thiol groups within proteins. This enzymatic activity is catalyzed by a family of enzymes known as sulfhydryl oxidases, which utilize flavin adenine dinucleotide (FAD) as a cofactor. The catalytic mechanism involves the following steps:

1. **Thiol substrate binding:** The enzyme binds to the thiol-containing substrate, typically a cysteine residue within a protein.
2. **Oxidation of thiol:** The FAD cofactor within the enzyme accepts electrons from the thiol group of the substrate, oxidizing it to a disulfide bond. This oxidation reaction is facilitated by the flavin's ability to cycle between its oxidized and reduced forms.
3. **Electron transfer:** The electrons from the oxidized thiol are transferred to molecular oxygen, which is reduced to water. This step requires the presence of molecular oxygen as an electron acceptor.
4. **Disulfide bond formation:** The oxidized thiol groups of two substrate molecules can then form a disulfide bond, stabilizing the protein structure and influencing its biological activity.

The flavin-dependent sulfhydryl oxidase activity plays a crucial role in various cellular processes, including:

* **Protein folding:** Disulfide bond formation mediated by sulfhydryl oxidases contributes to protein folding and stabilization.
* **Redox signaling:** The oxidation of thiol groups by sulfhydryl oxidases can act as a signaling mechanism in various cellular pathways.
* **Oxidative stress response:** Sulfhydryl oxidases are involved in cellular responses to oxidative stress by oxidizing thiol groups and contributing to redox homeostasis.
* **Extracellular matrix formation:** Sulfhydryl oxidases are essential for the formation and stability of extracellular matrix proteins, which provide structural support and regulate cell adhesion.

Overall, flavin-dependent sulfhydryl oxidase activity is an essential enzymatic function that governs the oxidation of thiol groups within proteins, influencing their structure, function, and cellular interactions.'
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Proteins (1)

Compounds (1)