In enzymology, a deoxyhypusine monooxygenase () is an enzyme that catalyzes the chemical reaction
The 3 substrates of this enzyme are a protein-bound N<sup>6</sup>-(4-aminobutyl)-<small>L</small>-lysine, an electron acceptor AH<sub>2</sub>, and O<sub>2</sub>, and its 3 products are protein-bound N<sup>6</sup>-[(R)-4-amino-2-hydroxybutyl]-<small>L</small>-lysine, the reduction product A, 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 derive from O miscellaneous. The systematic name of this enzyme class is deoxyhypusine,hydrogen-donor:oxygen oxidoreductase (2-hydroxylating). Other names in common use include deoxyhypusine hydroxylase, and deoxyhypusine dioxygenase.
The HUGO symbol for human gene and protein is DOHH, the full name is deoxyhypusine hydroxylase, and there are orthologs in other mammals. The orthologs have the same symbol, except for rodents, there the symbol is Dohh. The difference in case is just a meaningless historical artifact.