In molecular biology, group II pyridoxal-dependent decarboxylases are a family of enzymes including aromatic-L-amino-acid decarboxylase (L-dopa decarboxylase or tryptophan decarboxylase) that catalyse the decarboxylation of tryptophan to tryptamine, tyrosine decarboxylase that converts tyrosine into tyramine and histidine decarboxylase that catalyses the decarboxylation of histidine to histamine.
Pyridoxal-5'-phosphate-dependent amino acid decarboxylases can be divided into four groups based on amino acid sequence: group II includes glutamate, histidine, tyrosine, and aromatic-L-amino-acid decarboxylases.