. "The enzyme also reduces nitric oxide and hydroxylamine to ammonia, and sulfite to sulfide." . . . "Cytochrome c552" . "Cytochrome c nitrite reductase" . "Nitrite reductase (cytochrome; ammonia-forming)" . "Multiheme nitrite reductase" . "NH(3) + 2 H(2)O + 6 ferricytochrome c = nitrite + 6 ferrocytochrome c + 7 H(+)." . "Heme" . "Calcium" .