KEGG   ENZYME: 1.19.6.1Help
Entry
EC 1.19.6.1                 Enzyme                                 

Name
nitrogenase (flavodoxin)
Class
Oxidoreductases;
Acting on reduced flavodoxin as donor;
With dinitrogen as acceptor
BRITE hierarchy
Sysname
reduced flavodoxin:dinitrogen oxidoreductase (ATP-hydrolysing)
Reaction(IUBMB)
4 reduced flavodoxin + N2 + 16 ATP + 16 H2O = 4 oxidized flavodoxin + H2 + 2 NH3 + 16 ADP + 16 phosphate [RN:R05186]
Reaction(KEGG)
Substrate
reduced flavodoxin [CPD:C02745];
N2 [CPD:C00697];
ATP [CPD:C00002];
H2O [CPD:C00001]
Product
oxidized flavodoxin [CPD:C02869];
H2 [CPD:C00282];
NH3 [CPD:C00014];
ADP [CPD:C00008];
phosphate [CPD:C00009]
Comment
Requires Mg2+. It is composed of two components, dinitrogen reductase and dinitrogenase, that can be separated but are both required for nitrogenase activity. Dinitrogen reductase is a [4Fe-4S] protein, which, at the expense of ATP, transfers electrons from a dedicated flavodoxin to dinitrogenase. Dinitrogenase is a protein complex that contains either a molybdenum-iron cofactor, a vanadium-iron cofactor, or an iron-iron cofactor, that reduces dinitrogen in three succesive two-electron reductions from nitrogen to diimine to hydrazine to two molecules of ammonia. The reduction is initiated by formation of hydrogen. The enzyme can also reduce acetylene 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. Some enzymes utilize ferredoxin rather than flavodoxin as the electron donor (see EC 1.18.6.1, nitrogenase).
History
EC 1.19.6.1 created 1984, modified 2014
Pathway
Nitrogen metabolism
Metabolic pathways
Reference
1  [PMID:164247]
  Authors
Zumft WG, Mortenson LE.
  Title
The nitrogen-fixing complex of bacteria.
  Journal
Biochim. Biophys. Acta. 416 (1975) 1-52.
Reference
2  [PMID:4344006]
  Authors
Eady RR, Smith BE, Cook KA, Postgate JR
  Title
Nitrogenase of Klebsiella pneumoniae. Purification and properties of the component proteins.
  Journal
Biochem. J. 128 (1972) 655-75.
Reference
3  [PMID:3907625]
  Authors
Deistung J, Cannon FC, Cannon MC, Hill S, Thorneley RN
  Title
Electron transfer to nitrogenase in Klebsiella pneumoniae. nifF gene cloned and the gene product, a flavodoxin, purified.
  Journal
Biochem. J. 231 (1985) 743-53.
Other DBs
ExplorEnz - The Enzyme Database: 
IUBMB Enzyme Nomenclature: 
ExPASy - ENZYME nomenclature database: 
BRENDA, the Enzyme Database: 
CAS: 
9013-04-1

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