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

ReactionsEdit

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 stepEdit

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

Genetics Edit

The gene encoding the enzyme is located on chromosome 7 in humans.^[1]

See alsoEdit

• Aromatic amino acids

Reference Edit

External linksEdit

• MeSH Aromatic-L-Amino-Acid+Decarboxylases

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