Question

Nitrogenase enzyme involved in nitrogen fixation works best in:

• A. Aerobic conditions
• B. Anaerobic conditions
• C. Insensitive to oxygen
• D. Both aerobic and anaerobic conditions

Hint:

Nitrogen fixation is the chemical process in which the atmospheric nitrogen is converted into ammonia. Nitrogenase enzymes are extremely sensitive to oxygen, that is why it works in anaerobic conditions and bacteria such as Rhizobium have specialized structures called leghemoglobin which is used to remove oxygen from the environment.

Answer 1

The Correct Option is B

Nitrogenase, the enzyme facilitating biological nitrogen fixation, transforms atmospheric nitrogen (N2) into ammonia (NH3). This enzyme is extremely sensitive to oxygen, leading to its irreversible inactivation. Consequently, nitrogenase requires anaerobic conditions for effective operation. Many nitrogen-fixing organisms possess specialized adaptations to maintain a low oxygen partial pressure environment for nitrogenase activity. For instance, in legumes, leghemoglobin in root nodules creates an oxygen-free environment. This is critical because oxygen acts as an oxidizing agent, disrupting the nitrogenase enzyme's redox reactions. Thus, nitrogen fixation is optimal in the absence of oxygen.