In the mechanism of nitrogen reduction, ________ directly takes the place of the H₂ in the FeMo subunit of the enzyme nitrogenase. A) NH₃ B) N₂ C) HN=NH D) H₂N-NH₂ E) NADPH

Question

Quizplus · Accepted Answer

The FeMo cofactor in nitrogenase is coordinated by two bridging sulfides (S1 and S2) and one terminal sulfide (S0), as well as two homocitrate molecules. According to the mechanism of nitrogen reduction, the terminal sulfide in the FeMo cofactor is replaced by the nitrogen molecule (N2). This process requires the transfer of an electron from the reduced Fe protein to the FeMo cofactor, leading to the formation of a FeMo-N2 complex which subsequently undergoes a series of proton and electron transfers to form two molecules of ammonia (NH3). Therefore, the direct replacement of H2 (as stated in choice B) does not occur in the nitrogen reduction mechanism. Choices A, C, D, and E are also incorrect as they are not relevant to the nitrogen reduction process.

In the Mechanism of Nitrogen Reduction, ________ Directly Takes the Place