Question

Important enzymes involved in nitrogen fixation are -

• A. Nitrogenase and peptidase
• B. Nitrogenase and hexokinase
• C. Hexokinase and dehydrogenase
• D. Nitrogenase and hydrogenase

Hint:

Think of Nitrogenase as the "worker" that fixes nitrogen and Hydrogenase as the "recycler" that recovers wasted energy, making the whole process more efficient. Both are crucial for the organism.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The question asks to identify the key enzymes that are directly involved in the process of biological nitrogen fixation.
Step 2: Detailed Explanation:
The process of converting atmospheric nitrogen (\(N_2\)) to ammonia (\(NH_3\)) involves a complex interplay of enzymes.
Nitrogenase: This is the primary and essential enzyme complex that catalyzes the reduction of \(N_2\) to \(NH_3\). It is highly sensitive to oxygen. No nitrogen fixation can occur without it.
Hydrogenase: A significant side reaction of the nitrogenase enzyme is the production of hydrogen gas (\(H_2\)), which wastes energy (ATP) and reducing power (electrons). Many nitrogen-fixing organisms possess an "uptake hydrogenase" enzyme. This enzyme recaptures the \(H_2\) and oxidizes it, thereby recovering some of the energy that was lost. Therefore, hydrogenase is a very important enzyme for improving the overall efficiency of nitrogen fixation.
Peptidase, Hexokinase, Dehydrogenase: These are important enzymes in general cellular metabolism (protein breakdown, glycolysis, respiration) but are not the specific key enzymes of the nitrogen fixation pathway itself.
Step 3: Final Answer:
Both Nitrogenase (for the main reaction) and Hydrogenase (for improving efficiency) are the important enzymes involved in nitrogen fixation.