Hemerythrins - Respiratory Pigments

The Hemerythrins are rather rare. They take place in some animals belonging to the minor phyla like the sipunculid worms, some brachiopods, priapulids and in the polychaete Magelona. Hemerythrins are situated intra-cellularly, usually in Cells of the coelomic fluid or in blood cells as in Magelona. In spite of their name, Hemerythrins do not contain haee groups. Though they, contain ferrous iron, bound directly to the protein. They have molecular weights of about 75,000. These pigments are colorless while deoxygenated but turn reddish violet when oxygenated.