Consider the mechanisms of nitrogen assimilation and fixation in leguminous plants. Which enzyme complex is responsible for reducing atmospheric nitrogen gas into ammonia within root nodules?

💡 Solution & Explanation

Biological nitrogen fixation in root nodules of legumes is catalyzed by the nitrogenase enzyme complex harbored by symbiotic bacteria such as Rhizobium species, which converts inert atmospheric nitrogen into ammonia utilizing substantial ATP energy. Nitrate reductase and nitrite reductase process soil nitrates, while glutamine synthetase incorporates ammonia into amino acid synthesis. Nitrogenase is exceptionally sensitive to molecular oxygen, requiring leghemoglobin for protection.