Reaction: 12 reduced ferredoxin + 12 H+ + N2 + 40 ATP + 40 H2O = 12 oxidized ferredoxin + 3 H2 + 2 NH3 + 40 ADP + 40 phosphate
Other name(s): vnfD (gene name); vnfG (gene name); vnfK (gene name)
Systematic name: ferredoxin:dinitrogen oxidoreductase (ATP-hydrolysing, vanadium-dependent)
Comments: Requires Mg2+. This enzyme, originally isolated from the bacterium Azotobacter vinelandii, is a complex of two components (namely dinitrogen reductase and dinitrogenase). Dinitrogen reductase is a [4Fe-4S] protein, which, in the presence of ATP, transfers an electron from ferredoxin to the dinitrogenase component. Dinitrogenase is a vanadium-iron protein that reduces dinitrogen to two molecules of ammonia in three successive two-electron reductions via diazine and hydrazine. Compared with molybdenum-depedent nitrogenase (EC 1.18.6.1), this enzyme produces more dihydrogen and consumes more ATP per dinitrogen molecule being reduced. Unlike EC 1.18.6.1, this enzyme can also use CO as substrate, producing ethene, ethane and propane [7,9].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Eady, R.R., Richardson, T.H., Miller, R.W., Hawkins, M. and Lowe, D.J. The vanadium nitrogenase of Azotobacter chroococcum. Purification and properties of the Fe protein. Biochem. J. 256 (1988) 189-196. [PMID: 2851977]
2. Miller, R.W. and Eady, R.R. Molybdenum and vanadium nitrogenases of Azotobacter chroococcum. Low temperature favours N2 reduction by vanadium nitrogenase. Biochem. J. 256 (1988) 429-432. [PMID: 3223922]
3. Thorneley, R.N., Bergstrom, N.H., Eady, R.R. and Lowe, D.J. Vanadium nitrogenase of Azotobacter chroococcum. MgATP-dependent electron transfer within the protein complex. Biochem. J. 257 (1989) 789-794. [PMID: 2784670]
4. Dilworth, M.J., Eldridge, M.E. and Eady, R.R. Correction for creatine interference with the direct indophenol measurement of NH3 in steady-state nitrogenase assays. Anal. Biochem. 207 (1992) 6-10. [PMID: 1336937]
5. Dilworth, M.J., Eldridge, M.E. and Eady, R.R. The molybdenum and vanadium nitrogenases of Azotobacter chroococcum: effect of elevated temperature on N2 reduction. Biochem. J. 289 (1993) 395-400. [PMID: 8424785]
6. Eady, R.R. Current status of structure function relationships of vanadium nitrogenase. Coordinat. Chem. Rev. 237 (2003) 23-30.
7. Lee, C.C., Hu, Y. and Ribbe, M.W. Vanadium nitrogenase reduces CO. Science 329 (2010) 642. [PMID: 20689010]
8. Lee, C.C., Hu, Y. and Ribbe, M.W. Tracing the hydrogen source of hydrocarbons formed by vanadium nitrogenase. Angew Chem Int Ed Engl 50 (2011) 5545-5547. [PMID: 21538750]
9. Sippel, D. and Einsle, O. The structure of vanadium nitrogenase reveals an unusual bridging ligand. Nat. Chem. Biol. 13 (2017) 956-960. [PMID: 28692069]