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EC 1.7.2.6 Details

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EC number

1.7.2.6

Accepted name

hydroxylamine dehydrogenase

Reaction

hydroxylamine + H₂O + 4 ferricytochrome c = nitrite + 4 ferrocytochrome c + 5 H⁺

Other name(s)

HAO (ambiguous), hydroxylamine oxidoreductase (ambiguous), hydroxylamine oxidase (misleading)

Systematic name

hydroxylamine:ferricytochrome-c oxidoreductase (nitrite-forming)

CAS registry number

9075-43-8

Comment

The enzymes from the nitrifying bacterium Nitrosomonas europaea [1,4] and the methylotrophic bacterium Methylococcus capsulatus [5] are hemoproteins with seven c-type hemes and one specialized P-460-type heme per subunit. The enzyme converts hydroxylamine to nitrite via an enzyme-bound nitroxyl intermediate [3]. While nitrite is the main product, the enzyme from Nitrosomonas europaea can also produce nitric oxide by catalysing the activity of EC 1.7.2.9, hydroxylamine oxidase [2].

History

created 1972 as EC 1.7.3.4, part transferred 2012 to EC 1.7.2.6, modifed 2021, modified 2021

EC Tree

1 Oxidoreductases

1.1 Acting on the CH-OH group of donors

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

1.6.1 With NAD⁺ or NADP⁺ as acceptor

1.6.2 With a heme protein as acceptor

1.6.3 With oxygen as acceptor

1.6.4 With a disulfide as acceptor (deleted sub-subclass)

1.6.5 With a quinone or similar compound as acceptor

1.6.6 With a nitrogenous group as acceptor

1.6.7 With an iron-sulfur protein as acceptor (deleted sub-subclass)

1.6.8 With a flavin as acceptor (deleted sub-subclass)

1.6.99 With unknown physiological acceptors

1.6.99.1 NADPH dehydrogenase

1.6.99.2 created 1961 as EC 1.6.5.2, transferred 1965 to EC 1.6.99.2, deleted 2005

1.6.99.3 NADH dehydrogenase

1.6.99.4 created 1965, deleted 1972

1.6.99.5 NADH dehydrogenase (quinone)

1.6.99.6 NADPH dehydrogenase (quinone)

1.6.99.7 created 1972, modified 1981 (EC 1.6.99.10 created 1978, incorporated 1981), deleted 2003

1.6.99.8 created 1972, deleted 2002

1.6.99.9 created 1972, deleted 2002

1.6.99.10 created 1978, deleted 1981

1.6.99.11 created 1989, deleted 2002

1.6.99.12 created 1989, deleted 2002

1.6.99.13 created 1992, deleted 2002

1.7 Acting on other nitrogenous compounds as donors

1.8 Acting on a sulfur group of donors

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

1.11.1 Peroxidases

1.11.2 Peroxygenases

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

1.21.3.1 isopenicillin-N synthase

1.21.3.2 columbamine oxidase

1.21.3.3 reticuline oxidase

1.21.3.4 sulochrin oxidase [(+)-bisdechlorogeodin-forming]

1.21.3.5 sulochrin oxidase [(-)-bisdechlorogeodin-forming]

1.21.3.6 aureusidin synthase

1.21.3.7 tetrahydrocannabinolic acid synthase

1.21.3.8 cannabidiolic acid synthase

1.21.3.9 dichlorochromopyrrolate synthase

1.21.3.10 hercynylcysteine S-oxide synthase

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)