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.
Other name(s): reduced ferredoxin:dinitrogen oxidoreductase (ATP-hydrolysing)
Systematic name: ferredoxin:dinitrogen oxidoreductase (ATP-hydrolysing, molybdenum-dependent)
Comments: Requires Mg2+. The enzyme is a complex of two components (namely dinitrogen reductase 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 1.19.6.1 nitrogenase (flavodoxin)]. The enzyme does not reduce CO (cf. EC 1.18.6.2, vanadium-dependent nitrogenase).
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]