The Enzyme Database

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EC 1.18.6.1     
Accepted name: nitrogenase
Reaction: 8 reduced ferredoxin + 8 H+ + N2 + 16 ATP + 16 H2O = 8 oxidized ferredoxin + H2 + 2 NH3 + 16 ADP + 16 phosphate
For diagram of reaction, click here
Systematic name: reduced ferredoxin:dinitrogen oxidoreductase (ATP-hydrolysing)
Comments: Requires Mg2+. It is composed of two proteins that can be separated but are both required for nitrogenase activity. Dinitrogen reductase is a [4Fe-4S] protein, which, with two molecules of ATP and ferredoxin, generates an electron. The electron is transferred to the other protein, dinitrogenase (molybdoferredoxin). Dinitrogenase is a molybdenum-iron protein that reduces dinitrogen in three succesive two-electron reductions from nitrogen to diimine to hydrazine to two molecules of ammonia. The molybdenum may be replaced by vanadium or iron. 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 1.19.6.1 nitrogenase (flavodoxin)].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, UM-BBD, CAS registry number: 9013-04-1
References:
1.  Zumft, W.G., Paneque, A., Aparicio, P.J. and Losada, M. Mechanism of nitrate reduction in Chlorella. Biochem. Biophys. Res. Commun. 36 (1969) 980–986. [PMID: 4390523]
2.  Liang, J. and Burris, R.H. Hydrogen burst associated with nitrogenase-catalyzed reactions. Proc. Natl. Acad. Sci. USA 85 (1988) 9446–9450. [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 (2004) 11852–11863. [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 (2000) 7221–7228. [PMID: 10852721]
[EC 1.18.6.1 created 1978 as EC 1.18.2.1, transferred 1984 to EC 1.18.6.1, modified 2005]
 
 


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