IUBMB Enzyme Nomenclature


Accepted name: tyrosine N-monooxygenase

Reaction: L-tyrosine + 2 O2 + 2 NADPH + 2 H+ = (Z)-[4-hydroxyphenylacetaldehyde oxime] + 2 NADP+ + CO2 + 3 H2O (overall reaction)
(1a) L-tyrosine + O2 + NADPH + H+ = N-hydroxy-L-tyrosine + NADP+ + H2O

(1b) N-hydroxy-L-tyrosine + O2 + NADPH + H+ = N,N-dihydroxy-L-tyrosine + NADP+ + H2O

(1c) N,N-dihydroxy-L-tyrosine = (Z)-[4-hydroxyphenylacetaldehyde oxime] + CO2 + H2O

For diagram click here.

Other name(s): tyrosine N-hydroxylase; CYP79A1

Systematic name: L-tyrosine,NADPH:oxygen oxidoreductase (N-hydroxylating)

Comments: A heme-thiolate protein (P-450). This enzyme is involved in the biosynthesis of the cyanogenic glucoside dhurrin in sorghum, along with EC, 4-hydroxyphenylacetaldehyde oxime monooxygenase and EC, cyanohydrin β-glucosyltransferase. Some 2-(4-hydroxyphenyl)-1-nitroethane is formed as a side product.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 159447-19-5


1. Halkier, B.A. and Møller, B.L. The biosynthesis of cyanogenic glucosides in higher plants. Identification of three hydroxylation steps in the biosynthesis of dhurrin in Sorghum bicolor (L.) Moench and the involvement of 1-ACI-nitro-2-(p-hydroxyphenyl)ethane as an intermediate. J. Biol. Chem. 265 (1990) 21114-21121. [PMID: 2250015]

2. Sibbesen, O., Koch, B., Halkier, B.A. and Møller, B.L. Cytochrome P-450TYR is a multifunctional heme-thiolate enzyme catalyzing the conversion of L-tyrosine to p-hydroxyphenylacetaldehyde oxime in the biosynthesis of the cyanogenic glucoside dhurrin in Sorghum bicolor (L.) Moench. J. Biol. Chem. 270 (1995) 3506-3511. [PMID: 7876084]

3. Bak, S., Olsen, C.E., Halkier, B.A. and Møller, B.L. Transgenic tobacco and Arabidopsis plants expressing the two multifunctional sorghum cytochrome P450 enzymes, CYP79A1 and CYP71E1, are cyanogenic and accumulate metabolites derived from intermediates in dhurrin biosynthesis. Plant Physiol. 123 (2000) 1437-1448. [PMID: 10938360]

4. Nielsen, J.S. and Møller, B.L. Cloning and expression of cytochrome P450 enzymes catalyzing the conversion of tyrosine to p-hydroxyphenylacetaldoxime in the biosynthesis of cyanogenic glucosides in Triglochin maritima. Plant Physiol. 122 (2000) 1311-1321. [PMID: 10759528]

5. 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]

6. 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]

[EC created 1992, modified 2001, modified 2005]

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