Hydroxylamine dehydrogenase

Hydroxylamine dehydrogenase (EC 1.7.2.6, HAO (ambiguous)) is an enzyme with systematic name hydroxylamine:ferricytochrome-c oxidoreductase.^{[1][2][3][4][5]} This enzyme catalyses the following chemical reaction

(1) hydroxylamine + H₂O + 2 ferricytochrome c ${\displaystyle \rightleftharpoons }$ nitrite + 2 ferrocytochrome c + 5 H⁺

(2) hydroxylamine + ferricytochrome c ${\displaystyle \rightleftharpoons }$ nitric oxide + ferrocytochrome c + 3 H⁺

The enzymes from the nitrifying bacterium Nitrosomonas europaea and the methylotrophic bacterium Methylococcus capsulatus are hemoproteins.