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 NH2OH + A + H2O
Ammonia monooxygenase
Identifiers
EC number1.14.99.39
Databases
IntEnzIntEnz view
BRENDABRENDA entry
ExPASyNiceZyme view
KEGGKEGG entry
MetaCycmetabolic pathway
PRIAMprofile
PDB structuresRCSB PDB PDBe PDBsum

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.

References
  1. Hyman MR, Page CL, Arp DJ (August 1994). "Oxidation of methyl fluoride and dimethyl ether by ammonia monooxygenase in Nitrosomonas europaea". Applied and Environmental Microbiology. 60 (8): 3033–5. doi:10.1128/AEM.60.8.3033-3035.1994. PMC 201762. PMID 8085841.
  2. Bergmann DJ, Hooper AB (October 1994). "Sequence of the gene, amoB, for the 43-kDa polypeptide of ammonia monoxygenase of Nitrosomonas europaea". Biochemical and Biophysical Research Communications. 204 (2): 759–62. doi:10.1006/bbrc.1994.2524. PMID 7980540.
  3. Holmes AJ, Costello A, Lidstrom ME, Murrell JC (October 1995). "Evidence that particulate methane monooxygenase and ammonia monooxygenase may be evolutionarily related". FEMS Microbiology Letters. 132 (3): 203–8. doi:10.1111/j.1574-6968.1995.tb07834.x. PMID 7590173.
  4. Zahn JA, Arciero DM, Hooper AB, DiSpirito AA (November 1996). "Evidence for an iron center in the ammonia monooxygenase from Nitrosomonas europaea". FEBS Letters. 397 (1): 35–8. doi:10.1016/s0014-5793(96)01116-7. PMID 8941709.
  5. Moir JW, Crossman LC, Spiro S, Richardson DJ (May 1996). "The purification of ammonia monooxygenase from Paracoccus denitrificans". FEBS Letters. 387 (1): 71–4. doi:10.1016/0014-5793(96)00463-2. PMID 8654570.
  6. Whittaker M, Bergmann D, Arciero D, Hooper AB (August 2000). "Electron transfer during the oxidation of ammonia by the chemolithotrophic bacterium Nitrosomonas europaea". Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1459 (2–3): 346–55. doi:10.1016/s0005-2728(00)00171-7. PMID 11004450.
  7. Arp DJ, Sayavedra-Soto LA, Hommes NG (October 2002). "Molecular biology and biochemistry of ammonia oxidation by Nitrosomonas europaea". Archives of Microbiology. 178 (4): 250–5. doi:10.1007/s00203-002-0452-0. PMID 12209257.
  8. Gilch S, Meyer O, Schmidt I (September 2009). "A soluble form of ammonia monooxygenase in Nitrosomonas europaea". Biological Chemistry. 390 (9): 863–73. doi:10.1515/BC.2009.085. PMID 19453274.
  9. Rasche ME, Hicks RE, Hyman MR, Arp DJ (September 1990). "Oxidation of monohalogenated ethanes and n-chlorinated alkanes by whole cells of Nitrosomonas europaea". Journal of Bacteriology. 172 (9): 5368–73. doi:10.1128/jb.172.9.5368-5373.1990. PMC 213201. PMID 2394686.
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