EC - Dissimilatory sulfite reductase

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IntEnz Enzyme Nomenclature


Accepted name:
dissimilatory sulfite reductase
Other names:
siroheme sulfite reductase
hydrogen-sulfide:(acceptor) oxidoreductase (ambiguous)
Systematic name:
hydrogen-sulfide:[DsrC sulfur-carrier protein],acceptor oxidoreductase




Contain siroheme. The enzyme is essential in prokaryotic sulfur-based energy metabolism, including sulfate/sulfite reducing organisms, sulfur-oxidizing bacteria, and organosulfonate reducers. In sulfur reducers it catalyses the reduction of sulfite to sulfide (reaction 1 in the right to left direction), while in sulfur oxidizers it catalyses the opposite reaction (reaction 2 in the left to right direction) [1]. The reaction involves the small protein DsrC, which is present in all the organisms that contain dissimilatory sulfite reductase. During the process an intramolecular disulfide bond is formed between two L-cysteine residues of DsrC. This disulfide can be reduced by a number of proteins including DsrK and TcmB [5]. This enzyme is different from EC, assimilatory sulfite reductase (NADPH), and EC, assimilatory sulfite reductase (ferredoxin), which are involved in sulfate assimilation.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB


  1. Schedel, M., Vanselow, M. and Trueper, H.G.
    Siroheme sulfite reductase from Chromatium vinosum. Purification and investigation of some of its molecular and catalytic properties.
    Arch. Microbiol. 121: 29-36 (1979).
  2. Seki, Y., Sogawa, N., Ishimoto, M.
    Siroheme as an active catalyst in sulfite reduction.
    J. Biochem. 90: 1487-1492 (1981). [PMID: 7338517]
  3. Pott, A. S., Dahl, C.
    Sirohaem sulfite reductase and other proteins encoded by genes at the dsr locus of Chromatium vinosum are involved in the oxidation of intracellular sulfur.
    Microbiology (Reading, Engl.) 144: 1881-1894 (1998). [PMID: 9695921]
  4. Oliveira, T. F., Vonrhein, C., Matias, P. M., Venceslau, S. S., Pereira, I. A., Archer, M.
    The crystal structure of Desulfovibrio vulgaris dissimilatory sulfite reductase bound to DsrC provides novel insights into the mechanism of sulfate respiration.
    J. Biol. Chem. 283: 34141-34149 (2008). [PMID: 18829451]
  5. Venceslau, S. S., Stockdreher, Y., Dahl, C., Pereira, I. A.
    The "bacterial heterodisulfide" DsrC is a key protein in dissimilatory sulfur metabolism.
    Biochim. Biophys. Acta 1837: 1148-1164 (2014). [PMID: 24662917]

[EC created 1972, modified 2015]