Hydroxylamine oxioreductase catalyses the conversion of hydroxylamines to nitrite. This is the second step in the respiratory system of nitrifying chemoautotrophic bacteria. Ammonia mono-oxygenase produces hydroxylamine which is reduced by hydroxylamine oxioreductase to product electrons which feed into an electron transport chain to produce energy. The enzyme employs 24 haem groups across three sub units which interact in a uniquely complicated electron transport chain.
Defined by 5 residues: HIS:A-233ASP:A-267HIS:A-268TYR:A-334TYR:A_3-467