sentences:  For the past few decades, the common view was that a trimeric multiheme c-type HAO converts hydroxylamine into nitrite in the periplasm with production of four electrons (1.2).The stream of four electron are channelled through cytochrome c554 to a membrane-bound cytochrome c552.Two of the electrons are routed back to AMO, where they are used for the oxidation of ammonia (quinol pool).