Question

Which one of the following statements is TRUE about leghemoglobin?

• A. It binds oxygen to protect nitrogenase
• B. It binds hemoglobin to protect oxygenase
• C. It binds oxygen to protect hydrogenase
• D. It binds oxygen to protect oxygenase

Hint:

Nitrogenase is oxygen-sensitive; leghemoglobin acts as an oxygen buffer.
It ensures both protection of nitrogenase and energy supply for rhizobia.

Answer 1

The Correct Option is A

Step 1: Leghemoglobin is an oxygen-binding hemoprotein found in the root nodules of leguminous plants.
Step 2: The enzyme nitrogenase, which fixes atmospheric nitrogen into ammonia, is highly oxygen-sensitive and gets inactivated in the presence of oxygen.
Step 3: Leghemoglobin binds oxygen, maintaining a low free oxygen concentration in nodules, while still supplying enough oxygen for bacterial respiration.
Step 4: This protects nitrogenase from inactivation. Therefore, the correct answer is (A).