EC - Nitrite reductase (NO-forming)

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IntEnz Enzyme Nomenclature


Accepted name:
nitrite reductase (NO-forming)
Other names:
cd-cytochrome nitrite reductase
[nitrite reductase (cytochrome)] [misleading]
cytochrome c-551:O2, NO2+ oxidoreductase
cytochrome cd
cytochrome cd1
hydroxylamine (acceptor) reductase
methyl viologen-nitrite reductase
nitrite reductase (cytochrome; NO-forming)
Systematic name:
nitric-oxide:ferricytochrome-c oxidoreductase




The reaction is catalysed by two types of enzymes, generally found in the cytoplasm of denitrifying bacteria. One type comprises proteins containing multiple copper centres, the other a heme protein, cytochrome cd1. Acceptors include c-type cytochromes such as cytochrome c-552 or cytochrome c-553 from Pseudomonas denitrificans, and small blue copper proteins such as azurin and pseudoazurin. Cytochrome cd1 also has oxidase and hydroxylamine reductase activities. May also catalyse the reaction of hydroxylamine reductase (EC since this is a well-known activity of cytochrome cd1.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0050421
CAS Registry Number: 37256-41-0
UniProtKB/Swiss-Prot: (15) [show] [UniProt]


  1. Miyata, M. and Mori, T.
    Studies on denitrification. X. The "denitrifying enzyme" as a nitrite reductase and the electron donating system for denitrification.
    J. Biochem. (Tokyo) 66 : 463-471 (1969). [PMID: 5354021]
  2. Chung, C.W. and Najjar, V.A.
    Cofactor requirements for enzymatic denitrification. I. Nitrite reductase.
    J. Biol. Chem. 218 : 617-625 (1956).
  3. Walker, G.C. and Nicholas, D.J.D.
    Nitrite reductase from Pseudomonas aeruginosa.
    Biochim. Biophys. Acta 49 : 350-360 (1961).
  4. Singh, J.
    Cytochrome oxidase from Pseudomonas aeruginosa. III. Reduction of hydroxylamine.
    Biochim. Biophys. Acta 333 : 28-36 (1974).
  5. Michalski, W.P. and Nicholas, D.J.D.
    Molecular characterization of a copper-containing nitrite reductase from Rhodopseudomonas sphaeriodes forma sp. Denitrificans.
    Biochim. Biophys. Acta 828 : 130-137 (1985).
  6. Godden, J.W., Turley, S., Teller, D.C., Adman, E.T., Liu, M.Y., Payne, W.J. and Legall, J.
    The 2.3 angstrom X-ray structure of nitrite reductase from Achromobacter cycloclastes.
    Science 253 : 438-442 (1991). [PMID: 1862344]
  7. Williams, P.A., Fulop, V., Leung, Y.C., Chan, C., Moir, J.W.B., Howlett, G., Ferguson, S.J., Radford, S.E. and Hajdu, J.
    Pseudospecific docking surfaces on electron transfer proteins as illustrated by pseudoazurin, cytochrome c-550 and cytochrome cd1 nitrite reductase.
    Nat. Struct. Biol. 2 : 975-982 (1995). [PMID: 7583671]
  8. Hole, U.H., Vollack, K.U., Zumft, W.G., Eisenmann, E., Siddiqui, R.A., Friedrich, B. and Kroneck, P.M.H.
    Characterization of the membranous denitrification enzymes nitrite reductase (cytochrome cd1) and copper-containing nitrous oxide reductase from Thiobacillus denitrificans.
    Arch. Microbiol. 165 : 55-61 (1996). [PMID: 8639023]
  9. Zumft, W.G.
    Cell biology and molecular basis of denitrification.
    Microbiol. Mol. Biol. Rev. 61 : 533-616 (1997). [PMID: 9409151]
  10. Ferguson, S.J.
    Nitrogen cycle enzymology.
    Curr. Opin. Chem. Biol. 2 : 182-193 (1998). [PMID: 9667932]
  11. Vijgenboom, E., Busch, J.E. and Canters, G.W.
    In vitro studies disprove the obligatory role of azurin in denitrification in Pseudomonas aeruginosa and show that azu expression is under the control of RpoS and ANR.
    Microbiology 143 : 2853-2863 (1997). [PMID: 9308169]

[EC created 1961, modified 1976, modified 2001, modified 2002 (EC created 1961 as EC, transferred 1964 to EC, modified 1976, incorporated 2002) (EC created 1965, incorporated 2002)]