Heme biosynthesis (WP1086)

Canis familiaris

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


Caroline Miller , Jonathan Mélius , Martina Summer-Kutmon , and Eric Weitz


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Canis familiaris



Pathway Ontology

heme biosynthetic pathway


Label Type Compact URI Comment
O2 Metabolite hmdb:HMDB0001377
NH3 Metabolite hmdb:HMDB0000051
H2O2 Metabolite hmdb:HMDB0003125
O2 Metabolite hmdb:HMDB0001377
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
ALAS2 GeneProduct ncbigene:491498
FECH GeneProduct ncbigene:610360
PPOX GeneProduct ncbigene:478980
HMBS GeneProduct ncbigene:489373
ALAS1 GeneProduct ncbigene:476600
ALAD GeneProduct ncbigene:474808
UROS GeneProduct ncbigene:492116
UROD GeneProduct ncbigene:475378