These include lactoperoxidase, thyroid peroxidase, myeloperoxidase and eosinophil peroxidase. Although it is not firmly established that the heme group is identical in all species, there are enough similarities that these species should be classified together. These enzymes may all have a halide or pseudo-halide as electron donor, so the tentative suggestion is that the family be called halide peroxidases. The two isoenzymes of prostaglandin H synthase are distinct from the Class I animal peroxidases, with ferriprotoporphyrin IX as prosthetic group and the fatty acid binding channel on the proximal side of the heme. Class I. Animal.
Examples are beef liver catalase and human erythrocyte catalase.
It has never been clearly established whether the liver enzyme has one degraded heme in the intact organ or whether it is damaged in the isolation procedure. The erythrocyte catalase can be isolated with all four hemes intact. Nonetheless all of the animal catalases would appear to belong together. These include enzymes from E. coli , M. lysodeikticus and P. mirabilis . The bacterial enzymes appear to have heme d as a prosthetic group.