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EC 1.7.2.9 Details

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EC number

1.7.2.9

Accepted name

hydroxylamine oxidase

Reaction

hydroxylamine + 3 ferricytochrome c = nitric oxide + 3 ferrocytochrome c + 3 H⁺

Other name(s)

HOX

Systematic name

hydroxylamine:ferricytochrome-c oxidoreductase (nitric acid-forming)

CAS registry number

9075-43-8

Comment

The enzyme, characterized from the anaerobic ammonium-oxidizing (anammox) bacterium Kuenenia stuttgartiensis, is very similar to EC 1.7.2.6, hydroxylamine dehydrogenase. Both enzymes are homotrimeric enzymes in which each subunit contains seven c-type hemes and one specialized P460-type heme that is bound to a tyrosine residue in an adjacent subunit. However, this enzyme catalyses only the 3 electron oxidation of hydroxylamine, forming nitric oxide, and is not capable of performing further oxidation to form nitrite.

History

created 2021

EC Tree

1 Oxidoreductases

1.1 Acting on the CH-OH group of donors

1.1.1 With NAD⁺ or NADP⁺ as acceptor

1.1.2 With a cytochrome as acceptor

1.1.3 With oxygen as acceptor

1.1.4 With a disulfide as acceptor

1.1.5 With a quinone or similar compound as acceptor

1.1.7 With an iron-sulfur protein as acceptor

1.1.9 With a copper protein as acceptor

1.1.98 With other, known, physiological acceptors

1.1.99 With unknown physiological acceptors

1.2 Acting on the aldehyde or oxo group of donors

1.3 Acting on the CH-CH group of donors

1.4 Acting on the CH-NH₂ group of donors

1.5 Acting on the CH-NH group of donors

1.6 Acting on NADH or NADPH

1.7 Acting on other nitrogenous compounds as donors

1.7.1 With NAD⁺ or NADP⁺ as acceptor

1.7.2 With a cytochrome as acceptor

1.7.2.1 nitrite reductase (NO-forming)

1.7.2.2 nitrite reductase (cytochrome; ammonia-forming)

1.7.2.3 trimethylamine-N-oxide reductase

1.7.2.4 nitrous-oxide reductase

1.7.2.5 nitric oxide reductase (cytochrome c)

1.7.2.6 hydroxylamine dehydrogenase

1.7.2.7 hydrazine synthase

1.7.2.8 hydrazine dehydrogenase

1.7.2.9 hydroxylamine oxidase

1.7.3 With oxygen as acceptor

1.7.5 With a quinone or similar compound as acceptor

1.7.5.1 nitrate reductase (quinone)

1.7.5.2 nitric oxide reductase (menaquinol)

1.7.6 With a nitrogenous group as acceptor

1.7.7 With an iron-sulfur protein as acceptor

1.7.9 With a copper protein as acceptor

1.7.99 With unknown physiological acceptors

1.8 Acting on a sulfur group of donors

1.8.1 With NAD⁺ or NADP⁺ as acceptor

1.8.2 With a cytochrome as acceptor

1.8.3 With oxygen as acceptor

1.8.4 With a disulfide as acceptor

1.8.5 With a quinone or similar compound as acceptor

1.8.6 With a nitrogenous group as acceptor (deleted sub-subclass)

1.8.7 With an iron-sulfur protein as acceptor

1.8.98 With other, known, physiological acceptors

1.8.99 With unknown physiological acceptors

1.9 Acting on a heme group of donors

1.10 Acting on diphenols and related substances as donors

1.11 Acting on a peroxide as acceptor

1.12 Acting on hydrogen as donor

1.13 Acting on single donors with incorporation of molecular oxygen (oxygenases)

1.14 Acting on paired donors, with incorporation or reduction of molecular oxygen

1.15 Acting on superoxide as acceptor

1.16 Oxidizing metal ions

1.17 Acting on CH or CH₂ groups

1.18 Acting on iron-sulfur proteins as donors

1.19 Acting on reduced flavodoxin as donor

1.20 Acting on phosphorus or arsenic in donors

1.21 Catalysing the reaction X-H + Y-H = X-Y

1.21.1 With NAD⁺ or NADP⁺ as acceptor

1.21.3 With oxygen as acceptor

1.21.4 With a disulfide as acceptor

1.21.98 With other, known, physiological acceptors

1.21.99 With unknown physiological acceptors

1.22 Acting on halogen in donors

1.23 Reducing C-O-C group as acceptor

1.97 Other oxidoreductases

1.98 Enzymes using H₂ as reductant (deleted subclass)

1.99 Other enzymes using O₂ as oxidant (deleted subclass)