Heme Biosynthesis (Homo sapiens)
The pathway is initiated by the synthesis of D-Aminolevulinic acid (dALA or Î´ALA) from the amino acid glycine and succinyl-CoA from the citric acid cycle (Krebs cycle). The rate-limiting enzyme responsible for this reaction, ALA synthase, is strictly regulated by intracellular iron levels and heme concentration. A low-iron level, e.g., in iron deficiency, leads to decreased porphyrin synthesis, which prevents accumulation of the toxic intermediates. This mechanism is of therapeutic importance: infusion of heme arginate or hematin can abort attacks of porphyria in patients with an inborn error of metabolism of this process, by reducing transcription of ALA synthase.
The organs mainly involved in heme synthesis are the liver and the bone marrow, although every cell requires heme to function properly. Heme is seen as an intermediate molecule in catabolism of haemoglobin in the process of bilirubin metabolism.Source: Wikipedia http://en.wikipedia.org/wiki/Heme
- Polo CF, Vazquez ES, Caballero F, Gerez E, Battle AM; ''Heme biosynthesis pathway regulation in a model of hepatocarcinogenesis pre-initiation.; ''Comp Biochem Physiol B, 1992 - PubMed
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|ALAD||GeneProduct||210 (Entrez Gene)|
|HMBS||GeneProduct||3145 (Entrez Gene)|
|UROS||GeneProduct||7390 (Entrez Gene)|