Cysteine dioxygenase

Cysteine dioxygenase
cysteine dioxygenase, type I
Symbol CDO1
Entrez 1036
HUGO 1795
OMIM 603943
RefSeq NM_001801
UniProt Q16878
Other data
EC number
Locus Chr. 5 q23.2

Cysteine dioxygenase (CDO, CAS number: 37256-59-0)) is a mammalian non-heme iron enzyme that catalyzes the conversion of L-cysteine to cysteine sulfinic acid (cysteine sulfinate) by incorporation of dioxygen.

CDO reaction scheme showing cysteine sulfinic acid formation from cysteine by dioxygen incorporation

Cysteine sulfinic acid lies at a branch-point in cysteine catabolism, where it can follow two pathways resulting in the formation of taurine or sulfate. The cysteine sulfinic acid-dependent pathway of taurine metabolism follows the synthesis of hypotaurine (2-aminoethane sulfinate), which is subsequently oxidized to taurine. Also, cysteine sulfinate can undergo transamination to form β-sulfinylpyruvate, decomposing to form pyruvate and sulfite.


  • Sakakibara S, Yamaguchi K, Hosokawa Y, Kohashi N, Ueda I (February 1976). "Purification and some properties of rat liver cysteine oxidase (cysteine dioxygenase)". Biochim. Biophys. Acta 422 (2): 273–9. PMID 2307. 

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