Heme
Heme, or haem (pronounced /hi:m/ HEEM), is a precursor to hemoglobin. It is necessary to bind oxygen in the circulatory system. Heme is made in both the bone marrow and the liver.
Function
Hemes can do many things, such as catalyse reactions or move chemicals. Hemes are usually bound to proteins, and make hemoproteins.
Examples of hemoproteins include hemoglobin, myoglobin, leghemoglobin, and cytochrome.
Heme Media
Binding of oxygen to a heme prosthetic group
Space-filling model of the Fe-protoporphyrin IX subunit of heme B. Axial ligands omitted. Color scheme: grey=iron, blue=nitrogen, black=carbon, white=hydrogen, red=oxygen
The heme group of succinate dehydrogenase bound to histidine, an electron carrier in the mitochondrial electron transfer chain. The large semi-transparent sphere indicates the location of the iron ion. From PDB 1YQ3.
Porphyrine General Formula V.1
Structure of Fe-porphyrin subunit of heme B.
Structure of Fe-porphyrin subunit of heme A. Heme A is synthesized from heme B. In two sequential reactions a 17-hydroxyethylfarnesyl moiety is added at the 2-position and an aldehyde is added at the 8-position.
Heme synthesis in the cytoplasm and mitochondrion
Breakdown of Heme in macrophages and intestine
