:Carotenoid-9',10'-cleaving dioxygenase

{{Infobox enzyme

| Name = Carotenoid-9',10'-cleaving dioxygenase

| EC_number = 1.13.11.71

| CAS_number =

| GO_code =

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Carotenoid-9',10'-cleaving dioxygenase ({{EC number|1.13.11.71}}, BCO2 (gene), beta-carotene 9',10'-monooxygenase (misleading)) is an enzyme with systematic name all-trans-beta-carotene:O₂ oxidoreductase (9',10'-cleaving).{{cite journal | vauthors = Kiefer C, Hessel S, Lampert JM, Vogt K, Lederer MO, Breithaupt DE, von Lintig J | title = Identification and characterization of a mammalian enzyme catalyzing the asymmetric oxidative cleavage of provitamin A | journal = The Journal of Biological Chemistry | volume = 276 | issue = 17 | pages = 14110–6 | date = April 2001 | pmid = 11278918 | doi = 10.1074/jbc.M011510200 | doi-access = free }}{{cite journal | vauthors = Lindqvist A, He YG, Andersson S | title = Cell type-specific expression of beta-carotene 9',10'-monooxygenase in human tissues | journal = The Journal of Histochemistry and Cytochemistry | volume = 53 | issue = 11 | pages = 1403–12 | date = November 2005 | pmid = 15983114 | doi = 10.1369/jhc.5A6705.2005 | doi-access = free }} This enzyme catalyses the following chemical reaction

: all-trans-beta-carotene + O₂ $\backslash rightleftharpoons$ all-trans-10'-apo-beta-carotenal + beta-ionone

Carotenoid-9',10'-cleaving dioxygenase contains Fe²⁺.