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4-hydroxyphenylpyruvate dioxygenase
Identifiers
Symbol	HPPD
Alt. symbols	HPD; PPD
Entrez	3242
HUGO	5147
OMIM	609695
RefSeq	NM_002150
UniProt	P32754
Other data
EC number	1.13.11.27
Locus	Chr. 12 q24-qter

4-Hydroxyphenylpyruvate dioxygenase HPPD is an Fe-containing enzyme, that catalyzes the second reaction in the catabolism of tyrosine - the conversion of 4-hydroxyphenylpyruvate to homogentisate.

[edit] Function

The HPPD reaction occurs through a NIH shift and involves the oxidative decarboxylation of an α-oxo acid as well as aromatic ring hydroxylation. The NIH-shift, which has been demonstrated through isotope-labeling studies, involves migration of an alkyl group to form a more stable carbocation. The shift, accounts for the observation that C3 is bonded to C4 in 4-hydroxyphenylpyruvate but to C5 in homogentisate.

[edit] See also

• 4-hydroxyphenylpyruvate hydroxylase deficiency

Template:Alpha-keto acid dependent dioxygenases

v • d • e Metabolism: amino acid metabolism · synthesis and catabolism enzymes (essential in CAPS) K→acetyl-CoA LYSINE→ Saccharopine dehydrogenase · Glutaryl-CoA dehydrogenase LEUCINE→ Branched chain aminotransferase · Branched-chain alpha-keto acid dehydrogenase complex · Isovaleryl coenzyme A dehydrogenase · Methylcrotonyl-CoA carboxylase · Methylglutaconyl-CoA hydratase · 3-hydroxy-3-methylglutaryl-CoA lyase TRYPTOPHAN→ Indoleamine 2,3-dioxygenase/Tryptophan 2,3-dioxygenase · Arylformamidase · Kynureninase · 3-hydroxyanthranilate oxidase · Aminocarboxymuconate-semialdehyde decarboxylase · Aminomuconate-semialdehyde dehydrogenase PHENYLALANINE→tyrosine→ (see below) G G→pyruvate →citrate glycine→serine→ Serine hydroxymethyltransferase · Serine dehydratase glycine→creatine: Guanidinoacetate N-methyltransferase · Creatine kinase alanine→ Alanine transaminase cysteine→ D-cysteine desulfhydrase threonine→ L-threonine dehydrogenase G→glutamate→ α-ketoglutarate HISTIDINE→ Histidine ammonia-lyase · Urocanate hydratase · Formiminotransferase cyclodeaminase proline→ Proline oxidase · Pyrroline-5-carboxylate reductase · 1-Pyrroline-5-carboxylate dehydrogenase/ALDH4A1 · PYCR1 arginine→ Ornithine aminotransferase · Ornithine decarboxylase · Agmatinase →alpha-ketoglutarate→TCA Glutamate dehydrogenase Other cysteine+glutamate→glutathione: Gamma-glutamylcysteine synthetase · Glutathione synthetase · Gamma-glutamyl transpeptidase glutamate→glutamine: Glutamine synthetase · Glutaminase G→propionyl-CoA→ succinyl-CoA VALINE→ Branched chain aminotransferase · Branched-chain alpha-keto acid dehydrogenase complex · Enoyl-CoA hydratase · 3-hydroxyisobutyryl-CoA hydrolase · 3-hydroxyisobutyrate dehydrogenase · Methylmalonate semialdehyde dehydrogenase ISOLEUCINE→ Branched chain aminotransferase · Branched-chain alpha-keto acid dehydrogenase complex · 3-hydroxy-2-methylbutyryl-CoA dehydrogenase METHIONINE→ generation of homocysteine: Methionine adenosyltransferase · Adenosylhomocysteinase regeneration of methionine: MTR/Homocysteine methyltransferase · Betaine-homocysteine methyltransferase conversion to cysteine: Cystathionine beta synthase · Cystathionine gamma-lyase THREONINE→ Threonine aldolase →succinyl-CoA→TCA Propionyl-CoA carboxylase · Methylmalonyl CoA epimerase · Methylmalonyl-CoA mutase G→fumarate PHENYLALANINE→tyrosine→ Phenylalanine hydroxylase · Tyrosine aminotransferase · 4-Hydroxyphenylpyruvate dioxygenase · Homogentisate 1,2-dioxygenase · Fumarylacetoacetate hydrolase tyrosine→melanin: Tyrosinase G→oxaloacetate asparagine→aspartate→ Asparaginase/Asparagine synthetase · Aspartate transaminase see also disorders, intermediates

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