Heme biosynthesis (WP86)

Rattus norvegicus

The enzymatic process that produces heme is properly called porphyrin synthesis, as all the intermediates are tetrapyrroles that are chemically classified are porphyrins. The process is highly conserved across biology. In humans, this pathway serves almost exclusively to form heme. In other species, it also produces similar substances such as cobalamin (vitamin B12). The pathway is initiated by the synthesis of D-Aminolevulinic acid (dALA or δALA) 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


Kdahlquist , Caroline Miller , Christine Chichester , Egon Willighagen , Martina Summer-Kutmon , and Eric Weitz


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Rattus norvegicus



Pathway Ontology

heme biosynthetic pathway


Label Type Compact URI Comment
O2 Metabolite hmdb:HMDB0001377
NH3 Metabolite hmdb:HMDB0000051
succinyl-CoA Metabolite chemspider:83179
H2O2 Metabolite hmdb:HMDB0003125
O2 Metabolite hmdb:HMDB0001377
glycine Metabolite chemspider:730
delta-aminolevulinate Metabolite chemspider:10447539
CoA Metabolite hmdb:HMDB0001423
CO2 Metabolite hmdb:HMDB0001967
H2O Metabolite hmdb:HMDB0002111 Type your comment here
Porphobilinogen Metabolite hmdb:HMDB0000245
CO2 Metabolite hmdb:HMDB0001967
H2O Metabolite hmdb:HMDB0002111
H2O Metabolite hmdb:HMDB0002111
CO2 Metabolite hmdb:HMDB0001967
delta-aminolevulinate Metabolite chemspider:10447539
Alas2 GeneProduct ncbigene:25748
Fech GeneProduct ncbigene:361338
Ppox GeneProduct ncbigene:289219
Cpox GeneProduct ncbigene:304024
Hmbs GeneProduct ncbigene:25709
ALAS1 GeneProduct ncbigene:65155
Alad GeneProduct ncbigene:25374
Uros GeneProduct ncbigene:309070
Urod GeneProduct ncbigene:29421