The enzyme phenylalanine decarboxylase (EC 4.1.1.53) catalyzes the chemical reaction

L-phenylalanine phenethylamine + CO₂

This enzyme belongs to the family of lyases, specifically the carboxy-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is L-phenylalanine carboxy-lyase (phenylethylamine-forming). Other names in common use include L-phenylalanine decarboxylase, aromatic L-amino acid decarboxylase, and L-phenylalanine carboxy-lyase. This enzyme participates in phenylalanine metabolism. It employs one cofactor, pyridoxal phosphate.

• Lovenberg W, Weissbach H, Udenfriend S (1962). "Aromatic L-amino acid decarboxylase". J. Biol. Chem. 237: 89–93. doi:10.1016/S0021-9258(18)81366-7. PMID 14466899.
• Schulz AR, Oliner L (1967). "The possible role of thyroid aromatic amino acid decarboxylase in thyroxine biosynthesis". Life Sci. 6 (8): 873–80. doi:10.1016/0024-3205(67)90291-3. PMID 6034195.