Heme and Iron -- Main Menu


Heme metabolism is an important metabolic process because many important proteins contain heme as a prosthetic group. When these hemoproteins turn over, the heme is not salvaged, but is degraded. New heme is synthesized for their replacements. (text)

Heme is a member of a family of compounds called porphyrins. (text, sound, graphics, animation with sound)

Heme synthesis occurs partly in the mitochondria and partly in the cytoplasm. The process begins in the mitochondria because one of the precursors is found only there. Since this reaction is regulated in part by the concentration of heme, the final step (which produces the heme) is also mitochondrial. Most of the intermediate steps are cytoplasmic. (text,sound, graphics)

Summary of regulation of heme synthesis. (text)

Porphyrias are defects in porphyrin metabolism. (text,sound, graphics)

Heme degradation is an important metabolic process. (text,sound, graphics)

Iron metabolism is shaped by iron's status as an essential nutrient for which there is no mechanism for excreting any excesses that may accumulate in the body. (text)

Iron absorption is affected by the form in which iron is presented to the digestive tract, and inorganic iron ions change oxidation state during the absorption process. (text, graphics)

Regulation of iron uptake occurs at the basal membrane of the intestinal mucosal cells. These cells make an iron-binding protein, apoferritin. (text, graphics)

Iron transport and storage involve changes of oxidation state. The capacity of the plasma to transport iron is of clinical interest. Excess stored iron can cause pathology. (text, graphics)

Test yourself with some multiple choice exam questions. (text)

Return to the NetBiochem Welcome page, where you can choose another topic.


Last modified 10/8/97