IUBMB Enzyme Nomenclature


Accepted name: S-sulfosulfanyl-L-cysteine sulfohydrolase

Reaction: (1) [SoxY protein]-S-sulfosulfanyl-L-cysteine + H2O = [SoxY protein]-S-sulfanyl-L-cysteine + sulfate
(2) [SoxY protein]-S-(2-sulfodisulfanyl)-L-cysteine + H2O = [SoxY protein]-S-disulfanyl-L-cysteine + sulfate

Other name(s): SoxB

Systematic name: [SoxY protein]-S-sulfosulfanyl-L-cysteine sulfohydrolase

Comments: Contains Mn2+. The enzyme is part of the Sox enzyme system, which participates in a bacterial thiosulfate oxidation pathway that produces sulfate. It catalyses two reactions in the pathway. In both cases the enzyme hydrolyses a sulfonate moiety that is bound (either directly or via a sulfane) to a cysteine residue of a SoxY protein, releasing sulfate. The enzyme from Paracoccus pantotrophus contains a pyroglutamate (cycloglutamate) at its N-terminus.

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


1. Quentmeier, A. and Friedrich, C.G. The cysteine residue of the SoxY protein as the active site of protein-bound sulfur oxidation of Paracoccus pantotrophus GB17. FEBS Lett. 503 (2001) 168-172. [PMID: 11513876]

2. Friedrich, C.G., Rother, D., Bardischewsky, F., Quentmeier, A. and Fischer, J. Oxidation of reduced inorganic sulfur compounds by bacteria: emergence of a common mechanism. Appl. Environ. Microbiol. 67 (2001) 2873-2882. [PMID: 11425697]

3. Quentmeier, A., Hellwig, P., Bardischewsky, F., Grelle, G., Kraft, R. and Friedrich, C.G. Sulfur oxidation in Paracoccus pantotrophus: interaction of the sulfur-binding protein SoxYZ with the dimanganese SoxB protein. Biochem. Biophys. Res. Commun. 312 (2003) 1011-1018. [PMID: 14651972]

4. Epel, B., Schafer, K.O., Quentmeier, A., Friedrich, C. and Lubitz, W. Multifrequency EPR analysis of the dimanganese cluster of the putative sulfate thiohydrolase SoxB of Paracoccus pantotrophus. J. Biol. Inorg. Chem. 10 (2005) 636-642. [PMID: 16133204]

5. Hensen, D., Sperling, D., Truper, H.G., Brune, D.C. and Dahl, C. Thiosulphate oxidation in the phototrophic sulphur bacterium Allochromatium vinosum. Mol. Microbiol. 62 (2006) 794-810. [PMID: 16995898]

6. Grabarczyk, D.B. and Berks, B.C. Intermediates in the Sox sulfur oxidation pathway are bound to a sulfane conjugate of the carrier protein SoxYZ. PLoS One 12 (2017) e0173395. [PMID: 28257465]

[EC created 2018]

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