Aromatic L-amino acid decarboxylase

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.

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.

dopamine

serotonin

See also

• Aromatic amino acids

External links

• MeSH Aromatic-L-Amino-Acid+Decarboxylases