Heme prosthetic group (None commonly used (abbreviated as "heme" in literature, but no standard abbreviation like for protein targets))

The **heme prosthetic group** is an iron-containing macrocyclic molecule (protoporphyrin IX with a central iron ion) that acts as a non-protein cofactor in a wide range of biologically critical proteins, called hemoproteins. Heme enables these proteins to transport oxygen (hemoglobin, myoglobin), carry out electron transfer in cellular respiration (cytochromes), catalyze redox reactions (peroxidases, catalases, cytochrome P450s), and regulate signaling pathways. It is synthesized in the liver and bone marrow; its biosynthesis and degradation are tightly controlled as free heme can generate reactive oxygen species and is harmful to cells. While essential for many life-sustaining processes, the *heme group itself* is not a therapeutic target, but its role within drugs' actual molecular targets is critical for pharmacology and toxicology.

Other names

HemeHaem (British spelling)Iron-porphyrin cofactorFerroprotoporphyrin IX

For drugs targeting *heme* in proteins: Competitive binding to heme iron (e.g., CO competes with O₂ on hemoglobin); Inhibition of heme-containing enzymes (e.g., suicide inhibition of cytochrome P450s); Induction or inhibition of heme synthesis or degradation (e.g., barbiturates induce ALAS1 via CYP-hardware demand).