In enzymology, a 6ò-hydroxyhyoscyamine epoxidase () is an enzyme that catalyzes the chemical reaction
The 3 substrates of this enzyme are (6S)-6-hydroxyhyoscyamine, 2-oxoglutarate, and O<sub>2</sub>, whereas its 4 products are scopolamine, succinate, CO<sub>2</sub>, and H<sub>2</sub>O.
This enzyme belongs to the family of oxidoreductases, specifically those acting on paired donors, with O<sub>2</sub> as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O<sub>2</sub> with 2-oxoglutarate as one donor, and incorporation of one atom of oxygen into each donor. This enzyme participates in alkaloid biosynthesis ii. It has two cofactors: iron and ascorbate.
The systematic name of this enzyme class is (6S)-6-hydroxyhyoscyamine,2-oxoglutarate oxidoreductase (epoxide-forming). This enzyme is also called hydroxyhyoscyamine dioxygenase.