EC - Assimilatory sulfite reductase (NADPH)

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IntEnz Enzyme Nomenclature


Accepted name:
assimilatory sulfite reductase (NADPH)
Other names:
H2S-NADP oxidoreductase
NADPH-dependent sulfite reductase
NADPH-sulfite reductase
sulfite (reduced nicotinamide adenine dinucleotide phosphate) reductase
sulfite reductase (NADPH)
sulfite reductase (NADPH2)
MET5 (gene name)
MET10 (gene name)
cysI (gene name)
cysJ (gene name)
Systematic name:
hydrogen-sulfide:NADP+ oxidoreductase




Contains siroheme, [4Fe-4S] cluster, FAD and FMN. The enzyme, which catalyses the six-electron reduction of sulfite to sulfide, is involved in sulfate assimilation in bacteria and yeast. Different from EC, dissimilatory sulfite reductase, which is involved in prokaryotic sulfur-based energy metabolism.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00314
Structural data: CSA , EC2PDB
Gene Ontology: GO:0004783
CAS Registry Number: 9029-35-0
UniProtKB/Swiss-Prot: (239) [show] [UniProt]


  1. Hilz, H., Kittler, M. and Knape, G.
    Die Reduktion von Sulfate in der Hefe.
    Biochem. Z. 332 : 151-166 (1959). [PMID: 14401842]
  2. Siegel, L.M., Murphy, M.J. and Kamin, H.
    Reduced nicotinamide adenine dinucleotide phosphate-sulfite reductase of enterobacteria. I. The Escherichia coli hemoflavoprotein: molecular parameters and prosthetic groups.
    J. Biol. Chem. 248 : 251-264 (1973). [PMID: 4144254]
  3. Yoshimoto, A. and Sato, R.
    Studies on yeast sulfite reductase. I. Purification and characterization.
    Biochim. Biophys. Acta 153 : 555-575 (1968). [PMID: 4384979]
  4. Kobayashi, K., Yoshimoto, A.
    Studies on yeast sulfite reductase. IV. Structure and steady-state kinetics.
    Biochim. Biophys. Acta 705 : 348-356 (1982). [PMID: 6751400]
  5. Siegel, L. M., Rueger, D. C., Barber, M. J., Krueger, R. J., Orme-Johnson, N. R., Orme-Johnson, W. H.
    Escherichia coli sulfite reductase hemoprotein subunit. Prosthetic groups, catalytic parameters, and ligand complexes.
    J. Biol. Chem. 257 : 6343-6350 (1982). [PMID: 6281269]
  6. Coves, J., Zeghouf, M., Macherel, D., Guigliarelli, B., Asso, M., Fontecave, M.
    Flavin mononucleotide-binding domain of the flavoprotein component of the sulfite reductase from Escherichia coli.
    Biochemistry 36 : 5921-5928 (1997). [PMID: 9153434]
  7. Crane, B. R., Siegel, L. M., Getzoff, E. D.
    Structures of the siroheme- and Fe4S4-containing active center of sulfite reductase in different states of oxidation: heme activation via reduction-gated exogenous ligand exchange.
    Biochemistry 36 : 12101-12119 (1997). [PMID: 9315848]

[EC created 1961, modified 2015]