Center for Bioinformatics
Oxidoreductases | Transferases | Hydrolases | Lyases | Isomerases | Ligases

Basic Information

Enzyme Number

Official Name

phenylalanine 4-monooxygenase

Name from literature

phenylalanine hydroxylase

Pathway from literature

hepatic phenylalanine metabolism

Pathway from KEGG

Amino Acid Metabolism; Phenylalanine, tyrosine and tryptophan biosynthesis; map00400


Mouse (10090)

Genome localization

10 C2-D1|10 47.0 cM[18478 ],


The active centre contains mononuclear iron(II). The reaction involves an arene oxide that rearranges to give the phenolic hydroxy group. This results in the hydrogen at C-4 migrating to C-3 and in part being retained. This process is known as the NIH-shift. The 4a-hydroxytetrahydrobiopterin formed can dehydrate to 6,7-dihydrobiopterin, both spontaneously and by the action of EC, 4a-hydroxytetrahydrobiopterin dehydratase. The 6,7-dihydrobiopterin can be enzymically reduced back to tetrahydrobiopterin, by EC, 6,7-dihydropteridine reductase, or slowly rearranges into the more stable compound 7,8-dihydrobiopterin.

Rate-limiting Description

"The guanosine triphosphate (GTP) cyclohydrolase I (GTP-CHI) catalyses the rate-limiting step in the de novo synthesis of tetrahydrobiopterin, a cofactor of three aromatic amino acid hydroxylases, one of which is phenylalanine hydroxylase." (10984661)

Regulatory Information

Regulatory type





P16331:from_uniprot:16_Phosphoserine; by PKA

Gene ontology

Gene ontology

GO:0016597 (F) amino acid binding [P16331 ];
GO:0004505 (F) phenylalanine 4-monooxygenase activity [P16331 ];
GO:0006559 (P) L-phenylalanine catabolic process [P16331 ];
GO:0055114 (P) oxidation reduction [P16331 ];
GO:0005506 (F) iron ion binding [P16331 ];

Disease relevance


Mouse strains deficient in phenylalanine hydroxylase (Pah) were created as models of phenylketonuria (PKU) [P16331 ];




Entrez Gene


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  Last Modified: 2009-03-24  
  Design by Zhao Min