Aromatic L-amino acid decarboxylase

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Ribbon diagram of a domestic pig DOPA decarboxylase dimer. From PDB 1JS3.
DOPA decarboxylase (aromatic L-amino acid decarboxylase)
Identifiers
Symbol	DDC
Entrez	1644
HUGO	2719
OMIM	107930
RefSeq	NM_000790
UniProt	P20711
Other data
EC number	4.1.1.28
Locus	Chr. 7 p11

Aromatic L-amino acid decarboxylase (EC 4.1.1.28, synonyms: DOPA decarboxylase, tryptophan decarboxylase, 5-hydroxytryptophan decarboxylase, AAAD) is a lyase enzyme.

Contents 1 Reactions 2 As a rate limiting step 3 See also 4 External links

Reactions

It catalyzes several different decarboxylation reactions:

• L-DOPA to dopamine - a neurotransmitter
• 5-HTP to serotonin (5-HT) - also a neurotransmitter
• tryptophan to tryptamine - a precursor to many alkaloids found in plants and animals

The enzyme uses pyridoxal phosphate as a cofactor.

As a rate limiting step

In normal dopamine and serotonin (5-HT) neurotransmitter synthesis, AAAD is not the rate-limiting step of in either reaction. However, AAAD becomes the rate-limiting step of dopamine synthesis in patients treated with L-DOPA (such as in Parkinson's Disease), and the rate-limiting step of serotonin synthesis in people treated with 5-HTP (such as in mild depression or dysthymia).

AAAD is the rate-limiting enzyme in the formation of biogenic trace amines.

See also

• Aromatic amino acids

External links

• MeSH Aromatic-L-Amino-Acid+Decarboxylases

v • d • e Carbon-carbon lyases (EC 4.1)
4.1.1: Carboxy-lyases	Pyruvate decarboxylase -Oxaloacetate decarboxylase - Acetoacetate decarboxylase - Malonyl-CoA decarboxylase - Glutamate decarboxylase - Ornithine decarboxylase - Lysine decarboxylase - Phosphoribosylaminoimidazole carboxylase - Histidine decarboxylase - Uridine monophosphate synthetase/Orotidine 5'-phosphate decarboxylase - Aromatic L-amino acid decarboxylase - Phosphoenolpyruvate carboxylase - Pyrophosphomevalonate decarboxylase - Uroporphyrinogen III decarboxylase - RuBisCO - Phosphoenolpyruvate carboxykinase - Adenosylmethionine decarboxylase
4.1.2: Aldehyde-lyases	Aldolase A/Aldolase B - 2-hydroxyphytanoyl-CoA lyase
4.1.3: Oxo-acid-lyases	3-hydroxy-3-methylglutaryl-CoA lyase

v • d • e Amino acid metabolism enzymes (essential in CAPS)
K	LYSINE→acetyl-CoA Saccharopine dehydrogenase - Glutaryl-CoA dehydrogenase LEUCINE→acetyl-CoA Branched-chain alpha-keto acid dehydrogenase complex - Isovaleryl coenzyme A dehydrogenase - Methylcrotonyl-CoA carboxylase TRYPTOPHAN→acetyl-CoA Kynureninase PHENYLALANINE→tyrosine→acetoacetate (see below)
G	glycine→serine→pyruvate→TCA Serine hydroxymethyltransferase - Serine dehydratase alanine→pyruvate→TCA Alanine transaminase cysteine→pyruvate→TCA D-cysteine desulfhydrase threonine→pyruvate→TCA L-threonine dehydrogenase HISTIDINE→glutamate Histidine ammonia-lyase - Urocanate hydratase - Formiminotransferase cyclodeaminase proline→glutamate Proline oxidase - Pyrroline-5-carboxylate reductase - 1-Pyrroline-5-carboxylate dehydrogenase/ALDH4A1 - PYCR1 arginine→glutamate Ornithine aminotransferase - Ornithine decarboxylase - Agmatinase glutamate→alpha-ketoglutarate→TCA Glutamate dehydrogenase METHIONINE→propionyl-CoA Methionine adenosyltransferase - Adenosylhomocysteinase - (or MTR/Homocysteine methyltransferase) - Cystathionine beta synthase - Cystathionine gamma-lyase ISOLEUCINE/valine→propionyl-CoA Branched-chain alpha-keto acid dehydrogenase complex
NT	HISTIDINE→histamine Histidine decarboxylase tyrosine→dopamine→epinephrine Tyrosine hydroxylase - Aromatic L-amino acid decarboxylase - Dopamine beta hydroxylase - Phenylethanolamine N-methyltransferase - Catechol-O-methyl transferase glutamate→GABA Glutamate decarboxylase arginine→NO Nitric oxide synthase
Other	tyrosine→melanin Tyrosinase TRYPTOPHAN→serotonin→melatonin Tryptophan hydroxylase - Aromatic L-amino acid decarboxylase - Acetylserotonin O-methyltransferase cysteine+glutamate→glutathione Gamma-glutamylcysteine synthetase - Glutathione synthetase glycine→creatine Guanidinoacetate N-methyltransferase - Creatine kinase glutamate→glutamine Glutamine synthetase - Glutaminase collagen Prolyl hydroxylase - Lysyl hydroxylase
see also disorders, intermediates