The Enzyme Database

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EC 1.14.13.68      
Transferred entry: 4-hydroxyphenylacetaldehyde oxime monooxygenase. Now EC 1.14.14.37, 4-hydroxyphenylacetaldehyde oxime monooxygenase
[EC 1.14.13.68 created 2000, modified 2005, deleted 2016]
 
 
EC 1.14.14.37     
Accepted name: 4-hydroxyphenylacetaldehyde oxime monooxygenase
Reaction: (E)-4-hydroxyphenylacetaldehyde oxime + [reduced NADPH—hemoprotein reductase] + O2 = (S)-4-hydroxymandelonitrile + [oxidized NADPH—hemoprotein reductase] + 2 H2O (overall reaction)
(1a) (E)-4-hydroxyphenylacetaldehyde oxime = (Z)-4-hydroxyphenylacetaldehyde oxime
(1b) (Z)-4-hydroxyphenylacetaldehyde oxime = 4-hydroxyphenylacetonitrile + H2O
(1c) 4-hydroxyphenylacetonitrile + [reduced NADPH—hemoprotein reductase] + O2 = (S)-4-hydroxymandelonitrile + [oxidized NADPH—hemoprotein reductase] + H2O
For diagram of dhurrin biosynthesis, click here
Glossary: (S)-4-hydroxymandelonitrile = (2S)-hydroxy(4-hydroxyphenyl)acetonitrile
Other name(s): 4-hydroxybenzeneacetaldehyde oxime monooxygenase; cytochrome P450II-dependent monooxygenase; NADPH-cytochrome P450 reductase (CYP71E1); CYP71E1; 4-hydroxyphenylacetaldehyde oxime,NADPH:oxygen oxidoreductase
Systematic name: (E)-4-hydroxyphenylacetaldehyde oxime,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase
Comments: This cytochrome P-450 (heme thiolate) enzyme is involved in the biosynthesis of the cyanogenic glucoside dhurrin in sorghum. It catalyses three different activities - isomerization of the (E) isomer to the (Z) isomer, dehydration, and C-hydroxylation.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  MacFarlane, I.J., Lees, E.M. and Conn, E.E. The in vitro biosynthesis of dhurrin, the cyanogenic glycoside of Sorghum bicolor. J. Biol. Chem. 250 (1975) 4708–4713. [PMID: 237909]
2.  Shimada, M. and Conn, E.E. The enzymatic conversion of p-hydroxyphenylacetaldoxime to p-hydroxymandelonitrile. Arch. Biochem. Biophys. 180 (1977) 199–207. [DOI] [PMID: 193443]
3.  Busk, P.K. and Møller, B.L. Dhurrin synthesis in sorghum is regulated at the transcriptional level and induced by nitrogen fertilization in older plants. Plant Physiol. 129 (2002) 1222–1231. [DOI] [PMID: 12114576]
4.  Kristensen, C., Morant, M., Olsen, C.E., Ekstrøm, C.T., Galbraith, D.W., Møller, B.L. and Bak, S. Metabolic engineering of dhurrin in transgenic Arabidopsis plants with marginal inadvertent effects on the metabolome and transcriptome. Proc. Natl. Acad. Sci. USA 102 (2005) 1779–1784. [DOI] [PMID: 15665094]
5.  Clausen, M., Kannangara, R.M., Olsen, C.E., Blomstedt, C.K., Gleadow, R.M., Jørgensen, K., Bak, S., Motawie, M.S. and Møller, B.L. The bifurcation of the cyanogenic glucoside and glucosinolate biosynthetic pathways. Plant J. 84 (2015) 558–573. [DOI] [PMID: 26361733]
[EC 1.14.14.37 created 2000 as EC 1.14.13.68, modified 2005, transferred 2016 to EC 1.14.14.37]
 
 
EC 2.4.1.85     
Accepted name: cyanohydrin β-glucosyltransferase
Reaction: UDP-α-D-glucose + (S)-4-hydroxymandelonitrile = UDP + (S)-4-hydroxymandelonitrile β-D-glucoside
For diagram of dhurrin biosynthesis, click here
Glossary: dhurrin = (S)-4-hydroxymandelonitrile β-D-glucoside
Other name(s): uridine diphosphoglucose-p-hydroxymandelonitrile glucosyltransferase; UDP-glucose-p-hydroxymandelonitrile glucosyltransferase; uridine diphosphoglucose-cyanohydrin glucosyltransferase; uridine diphosphoglucose:aldehyde cyanohydrin β-glucosyltransferase; UDP-glucose:(S)-4-hydroxymandelonitrile β-D-glucosyltransferase; UGT85B1; UDP-glucose:p-hydroxymandelonitrile-O-glucosyltransferase; UDP-D-glucose:(S)-4-hydroxymandelonitrile β-D-glucosyltransferase
Systematic name: UDP-α-D-glucose:(S)-4-hydroxymandelonitrile β-D-glucosyltransferase (configuration-inverting)
Comments: Acts on a wide range of substrates in vitro, including cyanohydrins, terpenoids, phenolics, hexanol derivatives and plant hormones, in a regiospecific manner [3]. This enzyme is involved in the biosynthesis of the cyanogenic glucoside dhurrin in sorghum, along with EC 1.14.14.36, tyrosine N-monooxygenase and EC 1.14.14.37, 4-hydroxyphenylacetaldehyde oxime monooxygenase. This reaction prevents the disocciation and release of toxic hydrogen cyanide [3].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 55354-52-4
References:
1.  Reay, P.F. and Conn, E.E. The purification and properties of a uridine diphosphate glucose: aldehyde cyanohydrin β-glucosyltransferase from sorghum seedlings. J. Biol. Chem. 249 (1974) 5826–5830. [PMID: 4416442]
2.  Jones, P.R., Møller, B.L. and Hoj, P.B. The UDP-glucose:p-hydroxymandelonitrile-O-glucosyltransferase that catalyzes the last step in synthesis of the cyanogenic glucoside dhurrin in Sorghum bicolor. Isolation, cloning, heterologous expression, and substrate specificity. J. Biol. Chem. 274 (1999) 35483–35491. [DOI] [PMID: 10585420]
3.  Hansen, K.S., Kristensen, C., Tattersall, D.B., Jones, P.R., Olsen, C.E., Bak, S. and Møller, B.L. The in vitro substrate regiospecificity of recombinant UGT85B1, the cyanohydrin glucosyltransferase from Sorghum bicolor. Phytochemistry 64 (2003) 143–151. [DOI] [PMID: 12946413]
4.  Busk, P.K. and Møller, B.L. Dhurrin synthesis in sorghum is regulated at the transcriptional level and induced by nitrogen fertilization in older plants. Plant Physiol. 129 (2002) 1222–1231. [DOI] [PMID: 12114576]
5.  Kristensen, C., Morant, M., Olsen, C.E., Ekstrøm, C.T., Galbraith, D.W., Møller, B.L. and Bak, S. Metabolic engineering of dhurrin in transgenic Arabidopsis plants with marginal inadvertent effects on the metabolome and transcriptome. Proc. Natl. Acad. Sci. USA 102 (2005) 1779–1784. [DOI] [PMID: 15665094]
[EC 2.4.1.85 created 1976, modified 2005]
 
 
EC 4.1.2.11     
Accepted name: hydroxymandelonitrile lyase
Reaction: (S)-4-hydroxymandelonitrile = cyanide + 4-hydroxybenzaldehyde
Other name(s): hydroxynitrile lyase; oxynitrilase; Sorghum hydroxynitrile lyase; (S)-4-hydroxymandelonitrile hydroxybenzaldehyde-lyase
Systematic name: (S)-4-hydroxymandelonitrile 4-hydroxybenzaldehyde-lyase (cyanide-forming)
Comments: Does not accept aliphatic hydroxynitriles, unlike EC 4.1.2.10 (mandelonitrile lyase), EC 4.1.2.46 [aliphatic (R)-hydroxynitrile lyase] and EC 4.1.2.47 [(S)-hydroxynitrile ketone-lyase (cyanide forming)].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 9075-38-1
References:
1.  Bové, C. and Conn, E.E. Metabolism of aromatic compounds in higher plants. II. Purification and properties of the oxynitrilase of Sorghum vulgare. J. Biol. Chem. 236 (1961) 207–210.
2.  Seely, M.K., Criddle, R.S. and Conn, E.E. The metabolism of aromatic compounds in higher plants. 8. On the requirement of hydroxynitrile lyase for flavin. J. Biol. Chem. 241 (1966) 4457–4462. [PMID: 5922969]
[EC 4.1.2.11 created 1965, modified 1999]
 
 


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