:Menaquinol oxidase (H+-transporting)

{{Infobox enzyme

| Name = Menaquinol oxidase (H⁺-transporting)

| EC_number = 7.1.1.5

| CAS_number =

| GO_code =

| image =

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Menaquinol oxidase (H⁺-transporting) ({{EC number|7.1.1.5}}, cytochrome aa3-600 oxidase) is an enzyme with systematic name menaquinol:O2 oxidoreductase (H+-transporting).{{cite journal | vauthors = Lauraeus M, Wikström M | title = The terminal quinol oxidases of Bacillus subtilis have different energy conservation properties | journal = The Journal of Biological Chemistry | volume = 268 | issue = 15 | pages = 11470–3 | date = May 1993 | doi = 10.1016/S0021-9258(18)82147-0 | pmid = 8388393 | doi-access = free }}{{cite journal | vauthors = Lemma E, Simon J, Schägger H, Kröger A | title = Properties of the menaquinol oxidase (Qox) and of qox deletion mutants of Bacillus subtilis | journal = Archives of Microbiology | volume = 163 | issue = 6 | pages = 432–8 | date = June 1995 | pmid = 7575098 | doi = 10.1007/bf00272132 | s2cid = 38546234 }}{{cite journal | vauthors = Yi SM, Narasimhulu KV, Samoilova RI, Gennis RB, Dikanov SA | title = Characterization of the semiquinone radical stabilized by the cytochrome aa3-600 menaquinol oxidase of Bacillus subtilis | journal = The Journal of Biological Chemistry | volume = 285 | issue = 24 | pages = 18241–51 | date = June 2010 | pmid = 20351111 | pmc = 2883873 | doi = 10.1074/jbc.M110.116186 | doi-access = free }} This enzyme catalyses the following chemical reaction

: 2 menaquinol + O₂ $\backslash rightleftharpoons$ 2 menaquinone + 2 H₂O

Cytochrome aa3-600, one of the respiratory oxidases from Bacillus subtilis, is a member of the heme-copper family of oxygen reductases.