Ammonia monooxygenase

Ammonia monooxygenase (EC 1.14.99.39, AMO) is an enzyme,^{[1][2][3][4][5][6][7][8][9]} which catalyses the following chemical reaction

ammonia + AH₂ + O₂ ${\displaystyle \rightleftharpoons }$ NH₂OH + A + H₂O

Ammonia monooxygenase
Identifiers
EC no.	1.14.99.39
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Search PMC articles PubMed articles NCBI proteins

Ammonia monooxygenase contains copper and possibly nonheme iron. AMO is the first enzyme in ammonia oxidation. Aerobic oxidation of ammonia to hydroxylamine via AMO is an endergonic reaction. So, all aerobic ammonia oxidizing organisms conserve energy by further oxidizing hydroxylamine. It was believed that aerobic ammonia-oxidizing bacteria oxidize hydroxylamine to nitrite using octahaem hydroxylamine oxidoreductase (HAO). Recently, it was shown that the product of HAO is not nitrite but nitric oxide, which is further oxidized to nitrite by an unknown enzyme.