IUBMB Enzyme Nomenclature


Accepted name: assimilatory sulfite reductase (NADPH)

Reaction: hydrogen sulfide + 3 NADP+ + 3 H2O = sulfite + 3 NADPH + 3 H+

Other name(s): sulfite reductase (NADPH); sulfite (reduced nicotinamide adenine dinucleotide phosphate) reductase; NADPH-sulfite reductase; NADPH-dependent sulfite reductase; H2S-NADP oxidoreductase; sulfite reductase (NADPH2); MET5 (gene name); MET10 (gene name); cysI (gene name); cysJ (gene name)

Systematic name: hydrogen-sulfide:NADP+ oxidoreductase

Comments: 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. cf. EC, assimilatory sulfite reductase (ferredoxin).

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9029-35-0


1. Hilz, H., Kittler, M. and Knape, G. Die Reduktion von Sulfate in der Hefe. Biochem. Z. 332 (1959) 151-166. [PMID: 14401842]

2. Yoshimoto, A. and Sato, R. Studies on yeast sulfite reductase. I. Purification and characterization. Biochim. Biophys. Acta 153 (1968) 555-575. [PMID: 4384979]

3. 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 (1973) 251-264. [PMID: 4144254]

4. Kobayashi, K. and Yoshimoto, A. Studies on yeast sulfite reductase. IV. Structure and steady-state kinetics. Biochim. Biophys. Acta 705 (1982) 348-356. [PMID: 6751400]

5. Siegel, L.M., Rueger, D.C., Barber, M.J., Krueger, R.J., Orme-Johnson, N.R. and Orme-Johnson, W.H. Escherichia coli sulfite reductase hemoprotein subunit. Prosthetic groups, catalytic parameters, and ligand complexes. J. Biol. Chem. 257 (1982) 6343-6350. [PMID: 6281269]

6. Coves, J., Zeghouf, M., Macherel, D., Guigliarelli, B., Asso, M. and Fontecave, M. Flavin mononucleotide-binding domain of the flavoprotein component of the sulfite reductase from Escherichia coli. Biochemistry 36 (1997) 5921-5928. [PMID: 9153434]

7. Crane, B.R., Siegel, L.M. and 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 (1997) 12101-12119. [PMID: 9315848]

[EC created 1961, modified 2015]

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