IUBMB Enzyme Nomenclature


Accepted name: phenylalanine N-monooxygenase

Reaction: L-phenylalanine + 2 O2 + 2 [reduced NADPH—hemoprotein reductase] = (E)-phenylacetaldoxime + 2 [oxidized NADPH—hemoprotein reductase] + CO2 + 3 H2O (overall reaction)
(1a) L-phenylalanine + O2 + [reduced NADPH—hemoprotein reductase] = N-hydroxy-L-phenylalanine + [oxidized NADPH—hemoprotein reductase] + H2O
(1b) N-hydroxy-L-phenylalanine + O2 + [reduced NADPH—hemoprotein reductase] = N,N-dihydroxy-L-phenylalanine + [oxidized NADPH—hemoprotein reductase] + H2O
(1c) N,N-dihydroxy-L-phenylalanine = (E)-phenylacetaldoxime + CO2 + H2O

Other name(s): phenylalanine N-hydroxylase; CYP79A2 (gene name); CYP79D16 (gene name)

Systematic name: L-phenylalanine,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (N-hydroxylating)

Comments: This cytochrome P-450 (heme-thiolate) enzyme, found in plants, catalyses two successive N-hydroxylations of L-phenylalanine, a committed step in the biosynthesis of benzylglucosinolate and the cyanogenic glucosides (R)-prunasin and (R)-amygdalin. The product of the two hydroxylations, N,N-dihydroxy-L-phenylalanine, is labile and undergoes dehydration followed by decarboxylation, producing an oxime. It is still not known whether the decarboxylation is spontaneous or catalysed by the enzyme.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Wittstock, U. and Halkier, B.A. Cytochrome P450 CYP79A2 from Arabidopsis thaliana L. Catalyzes the conversion of L-phenylalanine to phenylacetaldoxime in the biosynthesis of benzylglucosinolate. J. Biol. Chem. 275 (2000) 14659-14666. [PMID: 10799553]

2. Yamaguchi, T., Yamamoto, K. and Asano, Y. Identification and characterization of CYP79D16 and CYP71AN24 catalyzing the first and second steps in L-phenylalanine-derived cyanogenic glycoside biosynthesis in the Japanese apricot, Prunus mume Sieb. et Zucc. Plant Mol. Biol. 86 (2014) 215-223. [PMID: 25015725]

[EC created 2011 as EC, transferred 2017 to EC]

Return to EC 1.14.14 home page
Return to EC 1.14 home page
Return to EC 1 home page
Return to Enzymes home page
Return to IUBMB Biochemical Nomenclature home page