L-dopa decarboxylase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: L-dopa + H+ = CO2 + dopamine. [GOC:bf, GOC:PARL, RHEA:12272]

L-Dopa decarboxylase activity is a critical enzymatic function responsible for catalyzing the conversion of L-dopa (levodopa), a precursor to dopamine, into dopamine. This reaction is essential for the biosynthesis of dopamine, a neurotransmitter playing a crucial role in various physiological processes, including movement, motivation, reward, and mood regulation. The enzyme responsible for this activity is known as aromatic L-amino acid decarboxylase (AADC), also referred to as dopa decarboxylase. AADC belongs to the pyridoxal phosphate-dependent decarboxylase family and utilizes pyridoxal phosphate (PLP) as a cofactor. The catalytic mechanism involves the following steps: 1. Binding of L-dopa to the active site of AADC. 2. Formation of a Schiff base intermediate between the amino group of L-dopa and the pyridoxal phosphate cofactor. 3. Decarboxylation of the Schiff base intermediate, releasing carbon dioxide and forming a quinonoid intermediate. 4. Hydrolysis of the quinonoid intermediate, releasing dopamine and regenerating the active enzyme. The activity of L-dopa decarboxylase is tightly regulated, ensuring adequate dopamine production while preventing excessive accumulation. In addition to L-dopa, AADC can also decarboxylate other aromatic L-amino acids, including 5-hydroxytryptophan (5-HTP), the precursor of serotonin. However, its primary role is in the biosynthesis of dopamine. Deficiencies in L-dopa decarboxylase activity can lead to neurodevelopmental disorders, such as dopamine-responsive dystonia, characterized by involuntary movements and impaired motor control. Conversely, excess L-dopa decarboxylase activity can contribute to neurodegenerative conditions like Parkinson's disease, where dopamine neurons are lost.'
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Proteins (1)

Compounds (4)