EC - Nitrogenase

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IntEnz Enzyme Nomenclature


Accepted name:
Other name:
reduced ferredoxin:dinitrogen oxidoreductase (ATP-hydrolysing)
Systematic name:
ferredoxin:dinitrogen oxidoreductase (ATP-hydrolysing, molybdenum-dependent)




Requires Mg2+. The enzyme is a complex of two components (namely dinitrogen reducatse and dinitrogenase). Dinitrogen reductase is a [4Fe-4S] protein, which, in the presence of two molecules of ATP, transfers an electron from ferredoxin to the dinitrogenase component. Dinitrogenase is a molybdenum-iron protein that reduces dinitrogen to two molecules of ammonia in three successive two-electron reductions via diazene and hydrazine. The reduction is initiated by formation of hydrogen in stoichiometric amounts [2]. Acetylene is reduced to ethylene (but only very slowly to ethane), azide to nitrogen and ammonia, and cyanide to methane and ammonia. In the absence of a suitable substrate, hydrogen is slowly formed. Ferredoxin may be replaced by flavodoxin [see EC nitrogenase (flavodoxin)]. The enzyme does not reduce CO (cf. EC, vanadium-dependent nitrogenase).

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UM-BBD , UniPathway
Protein domains and families: PROSITE:PDOC00085 , PROSITE:PDOC00580
Structural data: CSA , EC2PDB
Gene Ontology: GO:0018697 , GO:0016163
CAS Registry Number: 9013-04-1
UniProtKB/Swiss-Prot: (192) [show] [UniProt]


  1. Zumft, W.G., Paneque, A., Aparicio, P.J. and Losada, M.
    Mechanism of nitrate reduction in Chlorella.
    Biochem. Biophys. Res. Commun. 36 : 980-986 (1969). [PMID: 4390523]
  2. Liang, J. and Burris, R.H.
    Hydrogen burst associated with nitrogenase-catalyzed reactions.
    Proc. Natl. Acad. Sci. USA 85 : 9446-9450 (1989). [PMID: 3200830]
  3. Dance, I.
    The mechanism of nitrogenase. Computed details of the site and geometry of binding of alkyne and alkene substrates and intermediates.
    J. Am. Chem. Soc. 126 : 11852-11863 (2004). [PMID: 15382920]
  4. Chan, J.M., Wu, W., Dean, D.R. and Seefeldt, L.C.
    Construction and characterization of a heterodimeric iron protein: defining roles for adenosine triphosphate in nitrogenase catalysis.
    Biochemistry 39 : 7221-7228 (2000). [PMID: 10852721]

[EC created 1978 as EC, transferred 1984 to EC, modified 2005, modified 2018]