IUBMB Enzyme Nomenclature


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 reaction 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, CAS registry number:


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. [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. [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. [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. [PMID: 26361733]

[EC created 2000 as EC, modified 2005, transferred 2016 to EC]

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