Heme (Iron-protoporphyrin IX) (Heme)

Heme is a coordination complex consisting of an iron ion coordinated to a protoporphyrin IX ring, serving as the essential prosthetic group for hemoproteins like hemoglobin and myoglobin (StatPearls, 2023). In hemoglobin, heme facilitates the reversible binding and transport of oxygen from the lungs to tissues, while in myoglobin, it provides an oxygen reserve for muscle fibers (NIH, 2022). Heme is a critical therapeutic target in malaria treatment; Plasmodium parasites digest host hemoglobin, releasing toxic free heme which they must neutralize into hemozoin crystals. Antimalarial drugs such as chloroquine and quinine work by inhibiting this crystallization process, leading to the accumulation of toxic heme and subsequent parasite death (PubMed, 2021). Additionally, heme is the site of toxicity for carbon monoxide and cyanide, which bind to the iron center with significantly higher affinity than oxygen, thereby inhibiting cellular respiration and oxygen delivery (CDC, 2022).

Other names

Ferriprotoporphyrin IXHeminHematinIron-protoporphyrin IXHeme b

Inhibition of heme biocrystallization into hemozoin; competitive binding to the ferrous or ferric iron center; induction of oxidative stress through free heme accumulation (PubMed, 2021; StatPearls, 2023).