Hemozoin

Hemozoin (malaria pigment, β-hematin) is the chemically inert crystalline substance produced in the digestive food vacuole of blood-stage malaria parasites. The pigment is visible microscopically in intraerythrocytic stages that are actively degrading hemoglobin. During proteolysis of host erythrocyte hemoglobin, monomeric, toxic heme is released. In order to protect itself, the malaria parasite has evolved a distinct mechanism for detoxification of free heme through its conversion to insoluble and chemically inert β-hematin crystals called hemozoin. Hemozoin is a dark-brown pigment made of dimers of hematin molecules. The mechanism of hemozoin formation is still not well understood. Recent data suggest that in blood-stage malaria parasites, a multiproteinase complex, together with a heme detoxification protein, may mediate the formation of the pigment from heme. Hemozoin is also formed as a detoxification product of hemoglobin digestion in a variety of other blood-feeding parasites,...