Interrelationship between hydrogen peroxide, ammonia, glutamine, hydroxylamine and nitrite metabolism in the cyanobacterium Phormidium uncinatum

Abstract

On transition from nitrogen starvation to ammonia or ammonia/glutamine sufficiency Phormidium uncinatum produces high amounts of H2O2, which is consumed by several oxidative reactions catalyzed by thylakoid membrane bound enzymes. These include: oxidation of glutamine to free hydroxylamine, of ammonia to nitrite, of bound hydroxylamine to nitrite, and dismutation of free hydroxylamine to ammonia and nitrite. A possible role of these transformations for detoxification is discussed.