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Information on EC 1.14.99.64 - zeaxanthin 4-ketolase
for references in articles please use BRENDA:EC1.14.99.64
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EC Tree 1 Oxidoreductases
1.14 Acting on paired donors, with incorporation or reduction of molecular oxygen
1.14.99 Miscellaneous
1.14.99.64 zeaxanthin 4-ketolase
IUBMB Comments
The enzyme has a similar activity to that of EC 1.14.99.63, β-carotene 4-ketolase, but unlike that enzyme is able to also act on zeaxanthin.
The enzyme appears in viruses and cellular organisms
Reaction Schemes
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Synonyms
beta-carotene/zeaxanthin ketolase, bkt, CrtW148, more
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SYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
beta-carotene/zeaxanthin ketolase
bkt
CrtW148
-
-
-
-
bkt
-
-
ambiguous
-
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
adonixanthin + 2 reduced acceptor + 2 O2 = (3S,3'S)-astaxanthin + 2 acceptor + 3 H2O
(2)
-
-
-
zeaxanthin + 2 reduced acceptor + 2 O2 = adonixanthin + 2 acceptor + 3 H2O
(1)
-
-
-
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PATHWAY SOURCE
PATHWAYS
MetaCyc
astaxanthin biosynthesis (bacteria, fungi, algae)
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SYSTEMATIC NAME
IUBMB Comments
zeaxanthin,donor:oxygen oxidoreductase (adonixanthin-forming)
The enzyme has a similar activity to that of EC 1.14.99.63, beta-carotene 4-ketolase, but unlike that enzyme is able to also act on zeaxanthin.
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
LITERATURE
COMMENTARY
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
adonixanthin + 2 reduced acceptor + 2 O2
(3S,3'S)-astaxanthin + 2 acceptor + 3 H2O
Substrates: the enzyme is involved in biosynthesis of astaxanthin
Products: -
Products: -
?
adonixanthin + 2 reduced acceptor + 2 O2
(3S,3'S)-astaxanthin + 2 acceptor + 3 H2O
Substrates: the enzyme shows high (about 85%) conversion rate from zeaxanthin to astaxanthin
Products: -
Products: -
?
adonixanthin + 2 reduced acceptor + 2 O2
(3S,3'S)-astaxanthin + 2 acceptor + 3 H2O
Substrates: the enzyme is involved in biosynthesis of astaxanthin
Products: -
Products: -
?
adonixanthin + 2 reduced acceptor + 2 O2
(3S,3'S)-astaxanthin + 2 acceptor + 3 H2O
Substrates: the enzyme shows moderate (about 38%) conversion rate from zeaxanthin to astaxanthin
Products: -
Products: -
?
zeaxanthin + 2 reduced acceptor + 2 O2
adonixanthin + 2 acceptor + 3 H2O
Substrates: the enzyme is involved in biosynthesis of astaxanthin
Products: -
Products: -
?
zeaxanthin + 2 reduced acceptor + 2 O2
adonixanthin + 2 acceptor + 3 H2O
Substrates: the enzyme shows high (about 85%) conversion rate from zeaxanthin to astaxanthin
Products: -
Products: -
?
zeaxanthin + 2 reduced acceptor + 2 O2
adonixanthin + 2 acceptor + 3 H2O
Substrates: the enzyme is involved in biosynthesis of astaxanthin
Products: -
Products: -
?
zeaxanthin + 2 reduced acceptor + 2 O2
adonixanthin + 2 acceptor + 3 H2O
Substrates: the enzyme shows moderate (about 38%) conversion rate from zeaxanthin to astaxanthin
Products: -
Products: -
?
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NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
LITERATURE
COMMENTARY
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
adonixanthin + 2 reduced acceptor + 2 O2
(3S,3'S)-astaxanthin + 2 acceptor + 3 H2O
Substrates: the enzyme is involved in biosynthesis of astaxanthin
Products: -
Products: -
?
adonixanthin + 2 reduced acceptor + 2 O2
(3S,3'S)-astaxanthin + 2 acceptor + 3 H2O
Substrates: the enzyme is involved in biosynthesis of astaxanthin
Products: -
Products: -
?
zeaxanthin + 2 reduced acceptor + 2 O2
adonixanthin + 2 acceptor + 3 H2O
Substrates: the enzyme is involved in biosynthesis of astaxanthin
Products: -
Products: -
?
zeaxanthin + 2 reduced acceptor + 2 O2
adonixanthin + 2 acceptor + 3 H2O
Substrates: the enzyme is involved in biosynthesis of astaxanthin
Products: -
Products: -
?
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
Highest Expressing Human Cell Lines
Cell Line LinksPlease wait a moment until the data is sorted. This message will disappear when the data is sorted.
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
metabolism
physiological function
metabolism
the enzyme is involved in biosynthesis of astaxanthin
metabolism
the enzyme is involved in biosynthesis of astaxanthin
physiological function
Arabidopsis thaliana lines overexpressing the Chlamydomonas reinhardtii beta-carotene ketolase BKT accumulate high amounts of astaxanthin in the leaves. 1633 and 1722 genes are differentially expressed in the leaves and siliques, respectively, of BKT-overexpressing plants. These genes are enriched in the carotenoid biosynthetic pathways, and plant hormone biosynthesis and signaling pathways. As compared to the wild-type leaves and siliques, overexpression of BKT increases the levels of most amino acids, but decreases the contents of sugars and carbohydrates. Overexpressing plants have lower sensitivity to abscisic acid and increased tolerance to oxidative stress, and also exhibit enhanced resistance to the pathogen Pseudomonas syringae pv. tomato DC3000
physiological function
engineering the ketocarotenoid pathway into Chlamydomonas haploid vegetative green cells instead of the diploid zygospore stage by overexpressing beta-carotene ketolase. Overexpression results in the production of canthaxanthin, as well as a drastic reduction in the chlorophyll concentration. These phenotypes can only be detected from lines transformed and grown heterotrophically in the dark. Once exposed to light, these transformants lose their phenotypes as well as their antibiotic resistance
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UNIPROT
ENTRY NAME
ORGANISM
NO. OF AA
NO. OF TRANSM. HELICES
MOLECULAR WEIGHT[Da]
SOURCE
SEQUENCE
LOCALIZATION PREDICTION
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable).
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable). Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
expression in Escherichia coli
transgenic Arabidopsis thaliana expressing the beta-carotene ketolase from Chlamydomonas reinhardtii develop orange leaves which accumulate astaxanthin up to 2 mg/g dry weight with a 1.8fold increase in total carotenoids. The ketolases with high activity of converting zeaxanthin to astaxanthin triggers transgenic Arabidopsis to accumulate large amounts of astaxanthin in leaves and seeds
transgenic Arabidopsis thaliana expressing the beta-carotene ketolase from Chlamydomonas reinhardtii develop orange leaves which accumulate astaxanthin up to 2 mg/g dry weight with a 1.8fold increase in total carotenoids. The ketolases with high activity of converting zeaxanthin to astaxanthin triggers transgenic Arabidopsis to accumulate large amounts of astaxanthin in leaves and seeds
transgenic Arabidopsis thaliana expressing the beta-carotene ketolase from Chlamydomonas reinhardtii develop orange leaves which accumulate astaxanthin up to 2 mg/g dry weight with a 1.8fold increase in total carotenoids. The ketolases with high activity of converting zeaxanthin to astaxanthin triggers transgenic Arabidopsis to accumulate large amounts of astaxanthin in leaves and seeds
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APPLICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
agriculture
bioengineering of astaxanthin biosynthesis in rice endosperm. Transgenic overexpression of phytoene synthase and phytoene desaturase, of phytoene synthase, phytoene desaturase, zeaxanthin 4-ketolase, and all four genes phytoene synthase, phytoene desaturase, beta-carotene ketolase, and zeaxanthin hydroxylase driven by rice endosperm-specific promoters establish the carotenoid/ketocarotenoid/astaxanthin biosynthetic pathways in the endosperm and result in various types of germplasm, from yellow-grained beta-carotene-enriched Golden Rice to orange-red-grained Canthaxanthin Rice and Astaxanthin Rice, respectively. Grains of Astaxanthin Rice are enriched with astaxanthin in the endosperm and have higher antioxidant activity
synthesis
synthesis
bioengineering of astaxanthin biosynthesis in rice endosperm. Transgenic overexpression of phytoene synthase and phytoene desaturase, of phytoene synthase, phytoene desaturase, zeaxanthin 4-ketolase, and all four genes phytoene synthase, phytoene desaturase, beta-carotene ketolase, and zeaxanthin hydroxylase driven by rice endosperm-specific promoters establish the carotenoid/ketocarotenoid/astaxanthin biosynthetic pathways in the endosperm and result in various types of germplasm, from yellow-grained beta-carotene-enriched Golden Rice to orange-red-grained Canthaxanthin Rice and Astaxanthin Rice, respectively. Grains of Astaxanthin Rice are enriched with astaxanthin in the endosperm and have higher antioxidant activity
synthesis
engineering the ketocarotenoid pathway into Chlamydomonas haploid vegetative green cells instead of the diploid zygospore stage by overexpressing beta-carotene ketolase. Overexpression results in the production of canthaxanthin, as well as a drastic reduction in the chlorophyll concentration. These phenotypes can only be detected from lines transformed and grown heterotrophically in the dark. Once exposed to light, these transformants lose their phenotypes as well as their antibiotic resistance
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Zhong, Y.; Huang, J.; Liu, J.; Li, Y.; Jiang, Y.; Xu, Z.; Sandmann, G.; Chen, F.
Functional characterization of various algal carotenoid ketolases reveals that ketolating zeaxanthin efficiently is essential for high production of astaxanthin in transgenic Arabidopsis
J. Exp. Bot.
62
3659-3669
2011
Chlamydomonas reinhardtii (Q4VKB4), Chromochloris zofingiensis (Q5U931)
brenda
Yu, L.; Chen, Q.; Peng, Y.; Xie, L.; Liu, D.; Han, M.; Chen, F.; Xiao, S.; Huang, J.; Li, J.
Arabidopsis thaliana plants engineered to produce astaxanthin show enhanced oxidative stress tolerance and bacterial pathogen resistance
J. Agric. Food Chem.
67
12590-12598
2019
Chlamydomonas reinhardtii (Q4VKB4)
brenda
Zhu, Q.; Zeng, D.; Yu, S.; Cui, C.; Li, J.; Li, H.; Chen, J.; Zhang, R.; Zhao, X.; Chen, L.; Liu, Y.G.
From golden rice to aSTARice bioengineering astaxanthin biosynthesis in rice endosperm
Mol. Plant
11
1440-1448
2018
Chlamydomonas reinhardtii (Q4VKB4)
brenda
Tran, N.; Kaldenhoff, R.
Metabolic engineering of ketocarotenoids biosynthetic pathway in Chlamydomonas reinhardtii strain CC-4102
Sci. Rep.
10
10688
2020
Chlamydomonas reinhardtii (Q4VKB4)
brenda
EXTERNAL LINKS (specific for EC-Number 1.14.99.64)
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Release 2026.1 (March 2026)
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