ENZYME entry: EC

Accepted Name
Nitrogenase (flavodoxin).
Reaction catalysed
4 reduced flavodoxin + N(2) + 16 ATP + 16 H(2)O <=> 4 oxidized flavodoxin + H(2) + 2 NH(3) + 16 ADP + 16 phosphate
Fe(2+); Iron-sulfur; Mg(2+); Vanadium cation or Mo cation.
  • 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
  • Formerly EC
PRIAM enzyme-specific profiles1.19.6.1
KEGG Ligand Database for Enzyme Nomenclature1.19.6.1
IUBMB Enzyme Nomenclature1.19.6.1
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