Goat Anti-Human HDC polyclonal antibody for ELISA, WB. The biogenic amine histamine is an important modulator of numerous physiologic processes, including neurotransmission, gastric acid secretion, and smooth muscle tone. The biosynthesis of histamine from histidine is catalyzed by the enzyme L-histidine decarboxylase (HDC; EC 4.1.1.22). This homodimeric enzyme is a pyridoxal phosphate (PLP)-dependent decarboxylase and is highly specific for its histidine substrate.