Heme is an iron-containing porphyrin that is essential for hemoglobin function. Porphyrins are cyclic compounds formed from four pyrrole rings linked by methylene bridges that can bind metal ions. Heme synthesis primarily occurs in erythroid precursor cells in the bone marrow and liver cells, involving multiple enzymatic steps to convert the precursor uroporphyriinogen to protoporphyrin and insert iron.
2. Porphyrins are cyclic compounds formed by the linkage of four
pyrrole rings through methyne (=HC) bridges. A characteristic
property of the porphyrins is the formation of complexes with metal
ions bound to the nitrogen atom of the pyrrole rings. Examples are
the iron porphyrins such as heme of hemoglobin and the
magnesium-containing porphyrin chlorophyll, the photosynthetic
pigment of plants.
approximately 85% of heme synthesis occurs in erythroid precursor
cells in the bone marrow and the majority of the remainder in
hepatocytes.