rate-limiting unreviewed

Phenylalanine hydroxylase (PAH)

1 reactions · 1 pathways

Cofactors used

Clinical / pharmacological. Phenylketonuria: musty odour, intellectual disability, hypopigmentation; BH4 defects cause malignant PKU

What it does, reaction by reaction

1 reactions

Amino Acid Catabolism Overview (glucogenic vs. ketogenic amino acids; brief overview of branched-chain amino acid catabolism and phenylalanine/tyrosine catabolism as representative examples) Amino Acid & Nitrogen Metabolism · Cytosol + mitochondrion

step 9 Irreversible

L-phenylalanine + O₂ + tetrahydrobiopterin (BH₄) → L-tyrosine + H₂O + dihydrobiopterin (BH₂)

Converts Phenylalanine O2 Tetrahydrobiopterin (BH4) into Tyrosine H2O Dihydrobiopterin (BH2)

› Notes

Phenylalanine hydroxylase (PAH) catalyzes this irreversible hydroxylation; BH₄ is regenerated from BH₂ by dihydropteridine reductase using NADPH. This is the committed entry step for phenylalanine degradation and is also required to generate tyrosine when dietary tyrosine is insufficient.

Showing all 1 reactions.

What accelerates and inhibits it

Regulation is pathway-specific, so each context is listed separately

1 entries

Amino Acid Catabolism Overview (glucogenic vs. ketogenic amino acids; brief overview of branched-chain amino acid catabolism and phenylalanine/tyrosine catabolism as representative examples)

Listed there as: Phenylalanine hydroxylase

Accelerated by

Phenylalanine (allosteric/substrate activation); BH₄ availability

Inhibited by

BH₄ deficiency; inhibitory phosphorylation states/low substrate

Hormonal control

Mainly substrate and cofactor regulated; chronic nutritional/hormonal effects are indirect

Recent literature

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