Nitrogenases
Definition and meaning of Nitrogenases in chemistry.
Nitrogenases are enzymes produced by certain bacteria that are responsible for the reduction of atmospheric nitrogen to ammonia. They are the only known family of enzymes that accomplish this essential step in the nitrogen cycle.
In more detail
These complex metalloenzymes typically contain a molybdenum-iron (MoFe) protein and an iron (Fe) protein that work together. They require a significant input of energy in the form of ATP and a strong reducing agent to break the exceptionally strong triple bond of the N2 molecule. Because nitrogenases are highly sensitive to oxygen, nitrogen-fixing organisms have evolved various strategies to protect the enzyme from inactivation. The biological fixation of nitrogen is critical for supplying bioavailable nitrogen to natural ecosystems.
Key facts
| Field | Biochemistry |
|---|---|
| Substrate | N2 |
| Product | NH3 |
| Cofactor | FeMoco |
The nitrogenase complex in the bacterium Rhizobium leguminosarum converts N2 into NH3 within the root nodules of legume plants.
Frequently asked questions
Why are nitrogenases sensitive to oxygen?
The metal clusters within the enzyme are easily oxidized by O2, irreversibly destroying their catalytic activity.
What is the overall biological reaction?
N2 + 8H+ + 8e- + 16ATP yields 2NH3 + H2 + 16ADP + 16Pi.