DOPAdekarboxylas

DOPA decarboxylase (DDC), also known as DOPA decarboxylase, is a pyridoxal phosphate (PLP)-dependent enzyme that catalyzes the decarboxylation of aromatic L-amino acids. In humans, its primary reactions are the conversion of L-DOPA to dopamine and 5-hydroxytryptophan (5-HTP) to serotonin. The enzyme is encoded by the DDC gene and is expressed in central nervous system dopaminergic and serotonergic neurons as well as in peripheral tissues such as the gut, where monoamine production occurs locally. DDC is a cytosolic enzyme and is typically functional as a dimer, with each ~50 kDa subunit containing the PLP cofactor bound at an active site lysine.

Physiologically, DDC completes the final steps of two major neurotransmitter syntheses: dopamine from L-DOPA and serotonin from 5-HTP. In clinical practice, peripheral decarboxylation of L-DOPA by DDC can limit the amount of drug reaching the brain and cause side effects; therefore, DDC inhibitors such as carbidopa and benserazide are co-administered with L-DOPA in the treatment of Parkinson’s disease to reduce peripheral conversion and improve central availability of dopamine.

Genetic defects in DDC cause aromatic L-amino acid decarboxylase deficiency (AADC deficiency), a rare neurodevelopmental disorder presenting with hypotonia, developmental delays, oculogyric crises, and autonomic dysfunction. Management may include L-DOPA and 5-HTP supplementation and, in some cases, emerging gene therapy approaches.

DDC belongs to the family of PLP-dependent decarboxylases and is evolutionarily conserved across vertebrates and many invertebrates, reflecting its essential role in monoamine biosynthesis.