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EC 1.9.3.1 Details
EC number
1.9.3.1
Accepted name
cytochrome-c oxidase
Reaction
4 ferrocytochrome c + O2 + 4 H+ = 4 ferricytochrome c + 2 H2O
Other name(s)
cytochrome aa3,
cytochrome caa3,
cytochrome bb3,
cytochrome cbb3,
cytochrome ba3,
cytochrome a3,
Warburg’s respiratory enzyme,
indophenol oxidase,
indophenolase,
complex IV (mitochondrial electron transport),
ferrocytochrome c oxidase,
cytochrome oxidase (ambiguous),
NADH cytochrome c oxidase (incorrect)
Systematic name
ferrocytochrome-c:oxygen oxidoreductase
CAS registry number
9001-16-5
Comment
An oligomeric membrane heme-Cu: O2 reductase-type enzyme that terminates the respiratory chains of aerobic and facultative aerobic organisms. The reduction of O2 to water is accompanied by the extrusion of four protons. The aa3-type enzymes of mitochondria and many bacterial species are the most abundant group, but other variations, such as the bacterial cbb3 enzymes, also exist. All of the variants have a conserved catalytic core subunit (subunit I) that contains a low spin heme (of a- or b-type), a binuclear metal center composed of a high spin heme (of a-, o-, or b-type heme, referred to as a3, o3 or b3)-iron, and a Cu atom (CuB). Besides subunit I, the enzyme usually has at least two other core subunits: subunit II is the primary electron acceptor; subunit III usually does not contain any cofactors, but in the case of cbb3-type enzymes it is a diheme c-type cytochrome. While most bacterial enzymes consist of only 3-4 subunits, the mitochondrial enzyme is much more complex and contains 14 subunits.
History
created 1961, modified 2000, deleted 2019
EC Tree
1.9.3.2 created 1965, deleted 2002