IUBMB Enzyme Nomenclature


Accepted name: eukaryotic sulfide quinone oxidoreductase

Reaction: hydrogen sulfide + glutathione + a quinone = S-sulfanylglutathione + a quinol

Other name(s): SQR; SQOR; SQRDL (gene name)

Systematic name: sulfide:glutathione,quinone oxidoreductase

Comments: Contains FAD. This eukaryotic enzyme, located at the inner mitochondrial membrane, catalyses the first step in the metabolism of sulfide. While both sulfite and glutathione have been shown to act as sulfane sulfur acceptors in vitro, it is thought that the latter acts as the main acceptor in vivo. The electrons are transferred via FAD and quinones to the electron transfer chain. Unlike the bacterial homolog (EC, bacterial sulfide:quinone reductase), which repeats the catalytic cycle without releasing the product, producing a polysulfide, the eukaryotic enzyme transfers the persulfide to an acceptor at the end of each catalytic cycle.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number:


1. Vande Weghe, J.G. and Ow, D.W. A fission yeast gene for mitochondrial sulfide oxidation. J. Biol. Chem. 274 (1999) 13250-13257. [PMID: 10224084]

2. Hildebrandt, T.M. and Grieshaber, M.K. Three enzymatic activities catalyze the oxidation of sulfide to thiosulfate in mammalian and invertebrate mitochondria. FEBS J. 275 (2008) 3352-3361. [PMID: 18494801]

3. Jackson, M.R., Melideo, S.L. and Jorns, M.S. Human sulfide:quinone oxidoreductase catalyzes the first step in hydrogen sulfide metabolism and produces a sulfane sulfur metabolite. Biochemistry 51 (2012) 6804-6815. [PMID: 22852582]

4. Libiad, M., Yadav, P.K., Vitvitsky, V., Martinov, M. and Banerjee, R. Organization of the human mitochondrial hydrogen sulfide oxidation pathway. J. Biol. Chem. 289 (2014) 30901-30910. [PMID: 25225291]

[EC created 2017]

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