Why is leghaemoglobin called an oxygen scavenger?

Leghaemoglobin in legume root nodules is called an oxygen scavenger because it binds and buffers oxygen to keep very low free O₂ levels, protecting the nitrogen-fixing enzyme nitrogenase which is oxygen-sensitive.

• Source: produced by plant (globin) and rhizobial bacteria (heme) together.
• Role: maintains a pink nodule color; supplies enough O₂ for respiration but prevents nitrogenase inactivation.
• Outcome: efficient conversion of atmospheric N₂ to ammonia for the plant.