L-aromatic-amino-acid decarboxylase (AADC, also known as Dopa decarboxylase) (AADC (also DDC))

L-aromatic-amino-acid decarboxylase is an enzyme responsible for the conversion of L-threo-dihydroxyphenylserine (droxidopa/L-DOPS) into norepinephrine via a single-step enzymatic reaction. This process bypasses dopamine β-hydroxylase and is especially relevant in patients with deficiencies in this enzyme or with neurogenic orthostatic hypotension. The conversion occurs both in neuronal and non-neuronal tissues—including the kidneys—and can be inhibited by carbidopa, which does not cross the blood-brain barrier and thus blocks peripheral but not central conversion. Droxidopa is used therapeutically as a prodrug for norepinephrine to treat conditions such as orthostatic hypotension associated with autonomic failure syndromes and dopamine β-hydroxylase deficiency. The main safety concern during therapy is hypertension due to increased systemic norepinephrine levels.

Other names

Dopa decarboxylaseAromatic L-amino acid decarboxylaseL-aromatic-amino-acid decarboxylaseAADCDDC

Decarboxylation of catecholamine precursors such as droxidopa to produce norepinephrine