hydroxylamine dehydrogenase

{{Infobox enzyme

| Name = Hydroxylamine dehydrogenase

| EC_number = 1.7.2.6

| CAS_number = 9075-43-8

| GO_code =

| image =

| width =

| caption =

}}

Hydroxylamine dehydrogenase ({{EC number|1.7.2.6}}, HAO (ambiguous)) is an enzyme with systematic name hydroxylamine:ferricytochrome-c oxidoreductase.{{cite journal | vauthors = Rees MK | title = Studies of the hydroxylamine metabolism of Nitrosomonas europaea. I. Purification of hydroxylamine oxidase | journal = Biochemistry | volume = 7 | issue = 1 | pages = 353–66 | date = January 1968 | pmid = 5758552 | doi = 10.1021/bi00841a045 }}{{cite journal | vauthors = Hooper AB, Terry KR | title = Hydroxylamine oxidoreductase of Nitrosomonas. Production of nitric oxide from hydroxylamine | journal = Biochimica et Biophysica Acta | volume = 571 | issue = 1 | pages = 12–20 | date = November 1979 | pmid = 497235 | doi = 10.1016/0005-2744(79)90220-1 }}{{cite journal | vauthors = Hooper AB, Balny C | title = Reaction of oxygen with hydroxylamine oxidoreductase of Nitrosomonas: fast kinetics | journal = FEBS Letters | volume = 144 | issue = 2 | pages = 299–303 | date = August 1982 | pmid = 7117545 | doi = 10.1016/0014-5793(82)80658-3 | s2cid = 9726167 | doi-access = free | bibcode = 1982FEBSL.144..299H }}{{cite journal | vauthors = Lipscomb JD, Hooper AB | title = Resolution of multiple heme centers of hydroxylamine oxidoreductase from Nitrosomonas. 1. Electron paramagnetic resonance spectroscopy | journal = Biochemistry | volume = 21 | issue = 17 | pages = 3965–72 | date = August 1982 | pmid = 6289867 | doi = 10.1021/bi00260a010 }}{{cite journal | vauthors = Poret-Peterson AT, Graham JE, Gulledge J, Klotz MG | title = Transcription of nitrification genes by the methane-oxidizing bacterium, Methylococcus capsulatus strain Bath | journal = The ISME Journal | volume = 2 | issue = 12 | pages = 1213–20 | date = December 2008 | pmid = 18650926 | doi = 10.1038/ismej.2008.71 | doi-access = free | bibcode = 2008ISMEJ...2.1213P }} This enzyme catalyses the following chemical reaction

: (1) hydroxylamine + H₂O + 2 ferricytochrome c $\backslash rightleftharpoons$ nitrite + 2 ferrocytochrome c + 5 H⁺

: (2) hydroxylamine + ferricytochrome c $\backslash rightleftharpoons$ nitric oxide + ferrocytochrome c + 3 H⁺

The enzymes from the nitrifying bacterium Nitrosomonas europaea and the methylotrophic bacterium Methylococcus capsulatus are hemoproteins.