High Quality Content by WIKIPEDIA articles! Dual oxidase 2, also known as DUOX2 or ThOX2 (for thyroid oxidase) is an enzyme which in humans is encoded by the DUOX2 gene. Dual oxidase is an enzyme that was first identified in the mammalian thyroid gland. In humans, two isoforms are found; hDUOX1 and hDUOX2 (this enzyme). The protein location is not exclusive to thyroid tissue; hDUOX1 is prominent in airway epithelial cells and hDUOX2 in the salivary glands and gastrointestinal tract.