In molecular biology, group II pyridoxal-dependent decarboxylases are a family of enzymes including aromatic-L-amino-acid decarboxylase EC 4.1.1.28 that catalyse the decarboxylation of tryptophan to tryptamine, tyrosine decarboxylase EC 4.1.1.25 that converts tyrosine into tyramine and histidine decarboxylase EC 4.1.1.22 that catalyses the decarboxylation of histidine to histamine.