Nitrogenase Complex


The nitrogenase complex carries out the fixation of nitrogen by reducing molecular dinitrogen (N2) to ammonium ( ) and also reduces acetylene to ethylene. The two component proteins are dinitrogenase and dinitrogenase reductase. Although different metals can form the metal clusters contained in nitrogenase proteins, all nitrogenases have similar properties. The nitrogenase enzyme system is widely distributed among the Bacteria and the Archaea, with protein sequences highly conserved across the kingdoms.

Keywords: nitrogen fixation; nitrogenase; FeMo‐co; P cluster; dinitrogenase reductase; nif

Figure 1.

The path of electron flow in nitrogenase.

Figure 2.

Metal clusters of nitrogenase proteins.

Figure 3.

The acetylene reduction assay.



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Further Reading

Burgess BK and Lowe DJ (1996) Mechanism of molybdenum nitrogenase. Chemistry Review 96: 2983–3011.

Burris RH (1975) The acetylene‐reduction technique. In: Nitrogen Fixation by Free‐living Micro‐organisms, pp. 249–257. Cambridge: Cambridge University Press.

Eady RR (1996) Structure–function relationships of alternative nitrogenases. Chemistry Review 96: 3013–3030.

Elmerich C, Kondorosi A and Newton W (1998) Biological Nitrogen Fixation for the 21st Century. Dordrecht: Kluwer Academic.

Howard JB and Rees DC (1994) Nitrogenase: a nucleotide‐dependent molecular switch. Annual Review of Biochemistry 63: 235–264.

Ludden PW and Roberts GP (1989) Regulation of nitrogenase activity by reversible ADP‐ribosylation. Current Topics in Cellular Regulation 30: 23–55.

Peters JW, Stowell MHB, Soltis SM, Finnegan MG, Johnson MK and Rees DC (1997) Redox dependent structural changes in the nitrogenase P‐cluster. Biochemistry 36: 1181–1187.

Seefeldt LC and Dean DR (1997) Role of nucleotides in nitrogenase catalysis. Accounts of Chemical Research 30: 260–266.

Stacey G, Burris R and Evans H (eds) (1992) Biological Nitrogen Fixation. New York: Chapman & Hall.

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How to Cite close
Ludden, Paul W(Apr 2001) Nitrogenase Complex. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0001386]