Why some nitrogen-processing enzymes are more efficient than others

Nitrogen gas is abundant in Earth's atmosphere, but most living organisms can't readily use it. Only a subset of microbes with enzymes known as nitrogenases can break nitrogen gas apart and convert it into ammonia.

The top 3

  1. Molybdenum-Dependent Nitrogenase: The Gold Standard: Molybdenum-containing nitrogenases are the most efficient, wasting less ATP on hydrogen reduction and utilizing molybdenum to enhance iron's nitrogen-binding strength, which is crucial for breaking the N2 triple bond.
  2. Vanadium-Dependent Nitrogenase: The Secondary Option: Vanadium-dependent nitrogenase is the second most efficient class of nitrogen-fixing enzymes, typically utilized by microbes when molybdenum is scarce in the environment.
  3. Iron-Only Nitrogenase: The Least Efficient Backup: The iron-only nitrogenase is the least efficient of the three classes, serving as a backup mechanism when both molybdenum and vanadium are unavailable to the nitrogen-fixing microbes.

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