EC
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1.1.1.242
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Transferred entry: | zeatin reductase. Now EC 1.3.1.69, zeatin reductase
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[EC 1.1.1.242 created 1992, deleted 2001] |
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EC |
1.3.1.69 |
Accepted name: |
zeatin reductase |
Reaction: |
dihydrozeatin + NADP+ = zeatin + NADPH + H+ |
Glossary: |
zeatin.html">zeatin = (E)-2-methyl-4-(9H-purin-6-ylamino)but-2-en-1-ol = (E)-N6-(4-hydroxy-3-methylbut-2-enyl)adenine |
Systematic name: |
dihydrozeatin:NADP+ oxidoreductase |
Comments: |
Previously classified erroneously as EC 1.1.1.242. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 123644-82-6 |
References: |
1. |
Martin, R.C., Mok, M.C., Shaw, G. and Mok, D.W.S. An enzyme mediating the conversion of zeatin to dihydrozeatin in Phaseolus embryos. Plant Physiol. 90 (1989) 1630–1635. [PMID: 16666974] |
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[EC 1.3.1.69 created 1992 as EC 1.1.1.242, transferred 2001 to EC 1.3.1.69] |
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EC |
1.5.99.12 |
Accepted name: |
cytokinin dehydrogenase |
Reaction: |
N6-prenyladenine + acceptor + H2O = adenine + 3-methylbut-2-enal + reduced acceptor |
Glossary: |
zeatin.html">zeatin = (E)-2-methyl-4-(9H-purin-6-ylamino)but-2-en-1-ol = (E)-N6-(4-hydroxy-3-methylbut-2-enyl)adenine
N6-prenyladenine = N6-(3-methylbut-2-en-1-yl)purin-6-amine |
Other name(s): |
N6-dimethylallyladenine:(acceptor) oxidoreductase; 6-N-dimethylallyladenine:acceptor oxidoreductase; OsCKX2; CKX; cytokinin oxidase/dehydrogenase; N6-dimethylallyladenine:acceptor oxidoreductase |
Systematic name: |
N6-prenyladenine:acceptor oxidoreductase |
Comments: |
A flavoprotein (FAD). Catalyses the oxidation of cytokinins, a family of N6-substituted adenine derivatives that are plant hormones, where the substituent is a prenyl group. Although this activity was previously thought to be catalysed by a hydrogen-peroxide-forming oxidase, this enzyme does not require oxygen for activity and does not form hydrogen peroxide. 2,6-Dichloroindophenol, methylene blue, nitroblue tetrazolium, phenazine methosulfate and copper(II) in the presence of imidazole can act as acceptors. This enzyme plays a part in regulating rice-grain production, with lower levels of the enzyme resulting in enhanced grain production [2]. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 55326-39-1 |
References: |
1. |
Galuszka, P., Frebort, I., Sebela, M., Jacobsen, S. and Pec, P. Cytokinin oxidase or dehydrogenase? Mechanism of cytokinin degradation in plants. Eur. J. Biochem. 268 (2001) 450–461. [DOI] [PMID: 11168382] |
2. |
Ashikari, M., Sakakibara, H., Lin, S., Yamamoto, T., Takashi, T., Nishimura, A., Angeles, E.R., Qian, Q., Kitano, H. and Matsuoka, M. Cytokinin oxidase regulates rice grain production. Science 309 (2005) 741–745. [DOI] [PMID: 15976269] |
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[EC 1.5.99.12 created 2001] |
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EC |
1.14.99.69 |
Accepted name: |
tRNA 2-(methylsulfanyl)-N6-isopentenyladenosine37 hydroxylase |
Reaction: |
2-(methylsulfanyl)-N6-prenyladenosine37 in tRNA + reduced acceptor + O2 = N6-[(2E)-4-hydroxy-3-methylbut-2-en-1-yl]-2-(methylsulfanyl)adenosine37 in tRNA + acceptor + H2O |
Glossary: |
2-(methylsulfanyl)-N6-prenyladenosine = N6-(3-methylbut-2-en-1-yl)-2-(methylsulfanyl)adenosine |
Other name(s): |
miaE (gene name); tRNA 2-methylthio-N6-isopentenyl adenosine(37) hydroxylase; tRNA 2-(methylsulfanyl)-N6-dimethylallyladenosine37 hydroxylase |
Systematic name: |
tRNA 2-(methylsulfanyl)-N6-prenyladenosine37,donor:oxygen 4-oxidoreductase (trans-hydroxylating) |
Comments: |
The enzyme, found only within a small subset of facultative anaerobic bacteria, belongs to the nonheme diiron family. The enzyme from Salmonella typhimurium was shown to catalyse a stereoselective (E)-hydroxylation at the terminal C4-position of the prenyl group. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB |
References: |
1. |
Persson, B.C. and Bjork, G.R. Isolation of the gene (miaE) encoding the hydroxylase involved in the synthesis of 2-methylthio-cis-ribozeatin in tRNA of Salmonella typhimurium and characterization of mutants. J. Bacteriol. 175 (1993) 7776–7785. [DOI] [PMID: 8253666] |
2. |
Persson, B.C., Olafsson, O., Lundgren, H.K., Hederstedt, L. and Bjork, G.R. The ms2io6A37 modification of tRNA in Salmonella typhimurium regulates growth on citric acid cycle intermediates. J. Bacteriol. 180 (1998) 3144–3151. [DOI] [PMID: 9620964] |
3. |
Corder, A.L., Subedi, B.P., Zhang, S., Dark, A.M., Foss, F.W., Jr. and Pierce, B.S. Peroxide-shunt substrate-specificity for the Salmonella typhimurium O2-dependent tRNA modifying monooxygenase (MiaE). Biochemistry 52 (2013) 6182–6196. [DOI] [PMID: 23906247] |
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[EC 1.14.99.69 created 2020] |
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EC |
2.4.1.118 |
Accepted name: |
cytokinin 7-β-glucosyltransferase |
Reaction: |
UDP-glucose + an N6-alkylaminopurine = UDP + an N6-alkylaminopurine-7-β-D-glucoside |
Glossary: |
zeatin.html">zeatin = (E)-2-methyl-4-(9H-purin-6-ylamino)but-2-en-1-ol = (E)-N6-(4-hydroxy-3-methylbut-2-enyl)adenine |
Other name(s): |
uridine diphosphoglucose-zeatin 7-glucosyltransferase; cytokinin 7-glucosyltransferase; UDP-glucose:zeatin 7-glucosyltransferase |
Systematic name: |
UDP-glucose:N6-alkylaminopurine 7-glucosyltransferase |
Comments: |
Acts on a range of N6-substituted adenines, including zeatin and N6-benzylaminopurine, but not N6-benzyladenine. With some acceptors, 9-β-D-glucosides are also formed. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 72103-03-8 |
References: |
1. |
Entsch, B. and Letham, D.S. Enzymic glucosylation of the cytokinin, 6-benzylaminopurine. Plant Sci. Lett. 14 (1979) 205–212. |
2. |
Entsch, B., Parker, C.W., Letham, D.S. and Summons, R.E. Preparation and characterization, using high-performance liquid chromatography, of an enzyme forming glucosides of cytokinins. Biochim. Biophys. Acta 570 (1979) 124–139. [DOI] [PMID: 486500] |
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[EC 2.4.1.118 created 1984] |
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EC |
2.4.1.203 |
Accepted name: |
trans-zeatin O-β-D-glucosyltransferase |
Reaction: |
UDP-glucose + trans-zeatin = UDP + O-β-D-glucosyl-trans-zeatin |
Glossary: |
zeatin.html">zeatin = (E)-2-methyl-4-(9H-purin-6-ylamino)but-2-en-1-ol = (E)-N6-(4-hydroxy-3-methylbut-2-enyl)adenine |
Other name(s): |
zeatin O-β-D-glucosyltransferase; uridine diphosphoglucose-zeatin O-glucosyltransferase; zeatin O-glucosyltransferase |
Systematic name: |
UDP-glucose:trans-zeatin O-β-D-glucosyltransferase |
Comments: |
Unlike EC 2.4.1.215, cis-zeatin O-β-D-glucosyltransferase, UDP-D-xylose can also act as donor (cf. EC 2.4.2.40, zeatin O-β-D-xylosyltransferase). |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 123644-76-8 |
References: |
1. |
Dixon, S.C., Martin, R.C., Mok, R.C., Shaw, G. and Mok, D.W.S. Zeatin glycosylation enzymes in Phaseolus - isolation of O-glucosyltransferase from Phaseolus lunatus and comparison to O-xylosyltransferase from P. vulgaris. Plant Physiol. 90 (1989) 1316–1321. [PMID: 16666929] |
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[EC 2.4.1.203 created 1992, modified 2001] |
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EC
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2.4.1.204
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Transferred entry: | zeatin O-β-D-xylosyltransferase. Now EC 2.4.2.40, zeatin O-β-D-xylosyltransferase
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[EC 2.4.1.204 created 1992, deleted 2003] |
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EC |
2.4.1.215 |
Accepted name: |
cis-zeatin O-β-D-glucosyltransferase |
Reaction: |
UDP-glucose + cis-zeatin = UDP + O-β-D-glucosyl-cis-zeatin |
Glossary: |
zeatin.html">zeatin = (E)-2-methyl-4-(9H-purin-6-ylamino)but-2-en-1-ol = (E)-N6-(4-hydroxy-3-methylbut-2-enyl)adenine |
Systematic name: |
UDP-glucose:cis-zeatin O-β-D-glucosyltransferase |
Comments: |
The enzyme from maize can use cis-zeatin and UDP-glucose as substrates, but not cis-ribosylzeatin, trans-zeatin or trans-ribosylzeatin. Unlike EC 2.4.1.203, trans-zeatin O-β-D-glucosyltransferase, UDP-D-xylose cannot act as a donor. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 123644-76-8 |
References: |
1. |
Martin, R.C., Mok, M.C., Habben, J.E. and Mok, D.W.S. A maize cytokinin gene encoding an O-glucosyltransferase specific to cis-zeatin. Proc. Natl. Acad. Sci. USA 98 (2001) 5922–5926. [DOI] [PMID: 11331778] |
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[EC 2.4.1.215 created 2001] |
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EC |
2.4.2.40 |
Accepted name: |
zeatin O-β-D-xylosyltransferase |
Reaction: |
UDP-D-xylose + zeatin = UDP + O-β-D-xylosylzeatin |
Glossary: |
zeatin.html">zeatin = (E)-2-methyl-4-(9H-purin-6-ylamino)but-2-en-1-ol = (E)-N6-(4-hydroxy-3-methylbut-2-enyl)adenine |
Other name(s): |
uridine diphosphoxylose-zeatin xylosyltransferase; zeatin O-xylosyltransferase |
Systematic name: |
UDP-D-xylose:zeatin O-β-D-xylosyltransferase |
Comments: |
Does not act on UDP-glucose (cf. EC 2.4.1.103 alizarin 2-β-glucosyltransferase). |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 110541-22-5 |
References: |
1. |
Turner, J.E., Mok, D.W.S., Mok, M.C. and Shaw, G. Isolation and partial-purification of an enzyme catalyzing the formation of O-xylosylzeatin in Phaseolus vulgaris embryos. Proc. Natl. Acad. Sci. USA 84 (1987) 3714–3717. [DOI] [PMID: 16593839] |
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[EC 2.4.2.40 created 1992 as EC 2.4.1.204, transferred 2003 to EC 2.4.2.40] |
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EC |
2.5.1.50 |
Accepted name: |
zeatin 9-aminocarboxyethyltransferase |
Reaction: |
O-acetyl-L-serine + zeatin = lupinate + acetate |
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For diagram of reaction, click here |
Glossary: |
lupinate = (S)-2-amino-3-{[(E)-4-hydroxy-3-methylbut-2-enylamino]purin-9-yl}propanoate
zeatin.html">zeatin = (E)-2-methyl-4-(9H-purin-6-ylamino)but-2-en-1-ol = (E)-N6-(4-hydroxy-3-methylbut-2-enyl)adenine
O-acetyl-L-serine = O3-acetyl-L-serine = (2S)-3-acetyloxy-2-aminopropanoic acid |
Other name(s): |
β-(9-cytokinin)-alanine synthase; β-(9-cytokinin)alanine synthase; O-acetyl-L-serine acetate-lyase (adding N6-substituted adenine); lupinate synthetase; lupinic acid synthase; lupinic acid synthetase; 3-O-acetyl-L-serine:zeatin 2-amino-2-carboxyethyltransferase |
Systematic name: |
O-acetyl-L-serine:zeatin 2-amino-2-carboxyethyltransferase |
Comments: |
The enzyme acts not only on zeatin but also on other N6-substituted adenines. The reaction destroys their cytokinin activity and forms the corresponding 3-(adenin-9-yl)-L-alanine. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 88086-35-5 |
References: |
1. |
Entsch, B., Parker, C.W. and Letham, D.S. An enzyme from lupin seeds forming alanine derivatives of cytokinins. Phytochemistry 22 (1983) 375–381. |
2. |
Mok, D.W.S. and Mok, M.C. Cytokinin metabolism and action. Ann. Rev. Plant Physiol. Plant Mol. Biol. 52 (2001) 89–118. |
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[EC 2.5.1.50 created 1984 as EC 4.2.99.13, transferred 2002 to EC 2.5.1.50] |
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EC |
3.2.1.175 |
Accepted name: |
β-D-glucopyranosyl abscisate β-glucosidase |
Reaction: |
D-glucopyranosyl abscisate + H2O = D-glucose + abscisate |
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For diagram of abscisic-acid biosynthesis, click here |
Other name(s): |
AtBG1; ABA-β-D-glucosidase; ABA-specific β-glucosidase; ABA-GE hydrolase; β-D-glucopyranosyl abscisate hydrolase |
Systematic name: |
β-D-glucopyranosyl abscisate glucohydrolase |
Comments: |
The enzyme hydrolzes the biologically inactive β-D-glucopyranosyl ester of abscisic acid to produce active abscisate. Abscisate is a phytohormone critical for plant growth, development and adaption to various stress conditions. The enzyme does not hydrolyse β-D-glucopyranosyl zeatin [1]. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc |
References: |
1. |
Lee, K.H., Piao, H.L., Kim, H.Y., Choi, S.M., Jiang, F., Hartung, W., Hwang, I., Kwak, J.M., Lee, I.J. and Hwang, I. Activation of glucosidase via stress-induced polymerization rapidly increases active pools of abscisic acid. Cell 126 (2006) 1109–1120. [DOI] [PMID: 16990135] |
2. |
Kato-Noguchi, H. and Tanaka, Y. Effect of ABA-β-D-glucopyranosyl ester and activity of ABA-β-D-glucosidase in Arabidopsis thaliana. J. Plant Physiol. 165 (2008) 788–790. [DOI] [PMID: 17923167] |
3. |
Dietz, K.J., Sauter, A., Wichert, K., Messdaghi, D. and Hartung, W. Extracellular β-glucosidase activity in barley involved in the hydrolysis of ABA glucose conjugate in leaves. J. Exp. Bot. 51 (2000) 937–944. [DOI] [PMID: 10948220] |
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[EC 3.2.1.175 created 2011] |
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EC
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4.2.99.13
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Transferred entry: | β-(9-cytokinin)-alanine synthase. Now EC 2.5.1.50, zeatin 9-aminocarboxyethyltransferase
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[EC 4.2.99.13 created 1984, deleted 2002] |
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