Mutational Analysis of the Nitrogenase Carbon Monoxide Protective Protein CowN Reveals That a Conserved C-Terminal Glutamic Acid Residue Is Necessary for Its Activity.

Nitrogenase is the only enzyme that catalyzes the reduction of nitrogen gas into ammonia. Nitrogenase is tightly inhibited by the environmental gas carbon monoxide (CO). Many nitrogen fixing bacteria protect nitrogenase from CO inhibition using the protective protein CowN.