IUBMB Enzyme Nomenclature


Accepted name: β-carotene 3-hydroxylase

Reaction: β-carotene + 4 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + 2 O2 = zeaxanthin + 4 oxidized ferredoxin [iron-sulfur] cluster + 2 H2O (overall reaction)
(1a) β-carotene + 2 reduced ferredoxin [iron-sulfur] cluster + H+ + O2 = β-cryptoxanthin + 2 oxidized ferredoxin [iron-sulfur] cluster + H2O
(1b) β-cryptoxanthin + 2 reduced ferredoxin [iron-sulfur] cluster + H+ + O2 = zeaxanthin + 2 oxidized ferredoxin [iron-sulfur] cluster + H2O

For diagram of reaction click here or click here

Other name(s): β-carotene 3,3'-monooxygenase; CrtZ

Systematic name: β-carotene,reduced ferredoxin [iron-sulfur] cluster:oxygen 3-oxidoreductase

Comments: Requires ferredoxin and iron(II). Also acts on other carotenoids with a β-end group. In some species canthaxanthin is the preferred substrate.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Sun, Z., Gantt, E. and Cunningham, F.X., Jr. Cloning and functional analysis of the β-carotene hydroxylase of Arabidopsis thaliana. J. Biol. Chem. 271 (1996) 24349-24352. [PMID: 8798688]

2. Fraser, P.D., Miura, Y. and Misawa, N. In vitro characterization of astaxanthin biosynthetic enzymes. J. Biol. Chem. 272 (1997) 6128-6135. [PMID: 9045623]

3. Fraser, P.D., Shimada, H. and Misawa, N. Enzymic confirmation of reactions involved in routes to astaxanthin formation, elucidated using a direct substrate in vitro assay. Eur. J. Biochem. 252 (1998) 229-236. [PMID: 9523693]

4. Bouvier, F., Keller, Y., d'Harlingue, A. and Camara, B. Xanthophyll biosynthesis: molecular and functional characterization of carotenoid hydroxylases from pepper fruits (Capsicum annuum L.). Biochim. Biophys. Acta 1391 (1998) 320-328. [PMID: 9555077]

5. Linden, H. Carotenoid hydroxylase from Haematococcus pluvialis: cDNA sequence, regulation and functional complementation. Biochim. Biophys. Acta 1446 (1999) 203-212. [PMID: 10524195]

6. Zhu, C., Yamamura, S., Nishihara, M., Koiwa, H. and Sandmann, G. cDNAs for the synthesis of cyclic carotenoids in petals of Gentiana lutea and their regulation during flower development. Biochim. Biophys. Acta 1625 (2003) 305-308. [PMID: 12591618]

7. Choi, S.K., Matsuda, S., Hoshino, T., Peng, X. and Misawa, N. Characterization of bacterial β-carotene 3,3'-hydroxylases, CrtZ, and P450 in astaxanthin biosynthetic pathway and adonirubin production by gene combination in Escherichia coli. Appl. Microbiol. Biotechnol. 72 (2006) 1238-1246. [PMID: 16614859]

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