KEGG ENZYME: 1.7.3.6

ENZYME: 1.7.3.6

Entry

EC 1.7.3.6                  Enzyme

Name

hydroxylamine oxidase (cytochrome);
HAO (ambiguous);
hydroxylamine oxidoreductase (ambiguous);
hydroxylamine oxidase (misleading)

Class

Oxidoreductases;
Acting on other nitrogenous compounds as donors;
With oxygen as acceptor

Sysname

hydroxylamine:oxygen oxidoreductase

Reaction(IUBMB)

hydroxylamine + O2 = nitrite + H2O + H+ (overall reaction) [RN:R10230];
(1a) hydroxylamine + 2 ferricytochrome c = nitroxyl + 2 ferrocytochrome c + 2 H+ [RN:R10913];
(1b) nitroxyl + 2 ferrocytochrome c + O2 + H+ = nitrite + 2 ferricytochrome c + H2O (spontaneous) [RN:R10914]

Reaction(KEGG)

R10230 R10913 R10914

Substrate

hydroxylamine [CPD:C00192];
O2 [CPD:C00007];
ferricytochrome c [CPD:C00125];
nitroxyl [CPD:C20937];
ferrocytochrome c [CPD:C00126];
H+ [CPD:C00080]

Product

nitrite [CPD:C00088];
H2O [CPD:C00001];
H+ [CPD:C00080];
nitroxyl [CPD:C20937];
ferrocytochrome c [CPD:C00126];
ferricytochrome c [CPD:C00125]

Comment

The enzyme from the heterotrophic nitrifying bacterium Paracoccus denitrificans contains three to five non-heme, non-iron-sulfur iron atoms and interacts with cytochrome c556 and pseudoazurin [2,3]. Under anaerobic conditions in vitro only nitrous oxide is formed [3]. Presumably nitroxyl is released and combines with a second nitroxyl to give nitrous oxide and water. When oxygen is present, nitrite is formed.

History

EC 1.7.3.6 created 1972 as EC 1.7.3.4, part transferred 2013 to EC 1.7.3.6, modified 2015

Pathway

ec00910

Nitrogen metabolism

Reference

Authors

Kurokawa, M, Fukumori, Y and Yamanaka, T

Title

A hydroxylamine - cytochrome c reductase occurs in the heterotrophic nitrifier Arthrobacter globiformis.

Journal

Plant Cell Physiol 26:1439-1442 (1985)

Reference

2 [PMID:8253206]

Authors

Wehrfritz JM, Reilly A, Spiro S, Richardson DJ

Title

Purification of hydroxylamine oxidase from Thiosphaera pantotropha. Identification of electron acceptors that couple heterotrophic nitrification to aerobic denitrification.

Journal

FEBS Lett 335:246-50 (1993)
DOI:10.1016/0014-5793(93)80739-H

Reference

3 [PMID:8920986]

Authors

Moir JW, Wehrfritz JM, Spiro S, Richardson DJ

Title

The biochemical characterization of a novel non-haem-iron hydroxylamine oxidase from Paracoccus denitrificans GB17.

Journal

Biochem J 319 ( Pt 3):823-7 (1996)
DOI:10.1042/bj3190823

Reference

4 [PMID:9082922]

Authors

Wehrfritz J, Carter JP, Spiro S, Richardson DJ

Title

Hydroxylamine oxidation in heterotrophic nitrate-reducing soil bacteria and purification of a hydroxylamine-cytochrome c oxidoreductase from a Pseudomonas species.

Journal

Arch Microbiol 166:421-4 (1996)
DOI:10.1007/bf01682991

Other DBs

ExplorEnz - The Enzyme Database:

1.7.3.6

IUBMB Enzyme Nomenclature:

1.7.3.6

ExPASy - ENZYME nomenclature database:

1.7.3.6

BRENDA, the Enzyme Database:

1.7.3.6

CAS:

9075-43-8

LinkDB

DBGET integrated database retrieval system