1.7.3.6 cytochrome c554 - 1.7.3.6 cytochrome P-460 one heme in each HAO monomer is a highly unusual heme P460 that is the site of catalysis. Heme P460 contains two covalent cross-links between the porphyrin and a Tyr residue, structure analysis, overview 1.7.3.6 heme - 1.7.3.6 heme hydroxylamine oxidoreductase is a 24-heme homotrimeric enzyme 1.7.3.6 additional information non-heme iron enzyme 1.7.3.6 additional information does not contain cytochrome