Mechanism of the two-component molybdenum-dependent nitrogenase reaction

MoFe protein catalyzes the reduction of N2 and is reduced in turn by Fe protein.

The Fe protein is believed to undergo a three-state cycle, and the MoFe protein a nine-state cycle.

Binding of ATP to reduced Fe protein is thought to generate an altered conformation of Fe protein, with a very low reduction potential.

Transfer of the electron from reduced Fe protein to MoFe protein is accompanied by hydrolysis of bound ATP to oxidized Fe protein then dissociates from the MoFe protein (this is the rate-limiting step for reduction) and is regenerated by exchange with ATP and reduction back to the oxidation state.