Reductase - transfers electrons from a donor protein (like ferredoxin) to nitrogenase
- Known as an Fe protein for its iron-sulfur cluster
Nitrogenase - splits and reduces nitrogen
- Known as a MoFe protein for its presence of its iron-sulfur cluster AND iron-sulfur-molybdenum cluster
The passing of these electrons require that the two complexes come together
- Accomplished with the hydrolysis of ATP
- ATP hydrolysis causes a conformational change that brings the two halves together so that the electrons can be passed


Michigan State University

- Some bacteria and archaea are diazotrophic (nitrogen-fixing) splitting gaseous, atmospheric nitrogen and reducing it to ammonia
- The triple nitrogen bond is difficult to break because of the instability of highly reactive, high-energy intermediates in the pathway
- After intermediates are created, the reaction is downhill in terms of energy, making it easy, but getting there can be difficult
- The reactions require special catalysts (enzymes) not found in higher organisms
- Energetically expensive process
- Requires 16 ATP per mole of N2 split and reduced
- Split N2 - reduce to NH3
- N2 + 10H+ + 8e- -> 2 NH3+ + H2
Ferredoxin, Nitrogenase
Two parts - reductase and nitrogenase


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