DOPA decarboxylase (aromatic L-amino acid decarboxylase)
Ribbon diagram of a domestic pig DOPA decarboxylase dimer. From PDB 1JS3.
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 Genetics 4 See also 5 References 6 External links

[edit] 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.

[edit] As a rate-limiting step

In normal dopamine and serotonin (5-HT) neurotransmitter synthesis, AAAD is not the rate-limiting step 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 inhibited by Carbidopa outside of the blood brain barrier to inhibit the premature conversion of L-DOPA to Dopamine in the treatment of Parkinson's.

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

   

[edit] Genetics

The gene encoding the enzyme is referred to as DDC and located on chromosome 7 in humans.^[1] Single nucleotide polymorphisms and other gene variations have been investigated in relation to neuropsychiatric disorders, e.g., a one-base pair deletion at –601 and a four-base pair deletion at 722–725 in exon 1 in relation to bipolar affective disorder^[2] and autism.^[3]

[edit] See also

• Aromatic amino acids

[edit] References

[edit] External links

• MeSH Aromatic-L-Amino-Acid+Decarboxylases

This EC 4.1 enzyme-related article is a stub. You can help Wikipedia by expanding it. v • d • e

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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 (Aldolase A, Aldolase B, Aldolase C) · 2-hydroxyphytanoyl-CoA lyase · Threonine aldolase 4.1.3: Oxo-acid-lyases 3-hydroxy-3-methylglutaryl-CoA lyase 4.1.99: Other Tryptophanase

v • d • e Metabolism: amino acid metabolism - neurotransmitter enzymes monoamine histidine→histamine anabolism: Histidine decarboxylase catabolism: Histamine N-methyltransferase - Amine oxidase tyrosine→dopamine→epinephrine anabolism: Tyrosine hydroxylase - Aromatic L-amino acid decarboxylase - Dopamine beta hydroxylase - Phenylethanolamine N-methyltransferase catabolism: Catechol-O-methyl transferase - Monoamine oxidase glutamate→GABA anabolism: Glutamate decarboxylase catabolism: 4-aminobutyrate aminotransferase - 4-aminobutyrate transaminase tryptophan→serotonin→melatonin Tryptophan hydroxylase - Aromatic L-amino acid decarboxylase - Acetylserotonin O-methyltransferase arginine→NO Nitric oxide synthase (NOS1, NOS2A, NOS3) choline→Acetylcholine anabolism: Choline acetyltransferase catabolism: Cholinesterase (Acetylcholinesterase, Butyrylcholinesterase) see also intermediates