Porphobilinogen synthase

Porphobilinogen synthase
porphobilinogen synthase
EC number
CAS number 9036-37-7
IntEnz IntEnz view
ExPASy NiceZyme view
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / EGO
Delta-aminolevulinic acid dehydratase
Symbol ALAD
Entrez 210
HUGO 395
OMIM 125270
RefSeq NM_001003945
UniProt P13716
Other data
EC number
Locus Chr. 9 q32
PDB 1b4k EBI.jpg
high resolution crystal structure of a mg2-dependent 5-aminolevulinic acid dehydratase
Symbol ALAD
Pfam PF00490
Pfam clan CL0036
InterPro IPR001731
SCOP 1aw5

Porphobilinogen synthase (or ALA dehydratase, or aminolevulinate dehydratase) synthesizes porphobilinogen through the asymmetric condensation of two molecules of aminolevulinic acid. All natural tetrapyrroles, including hemes, chlorophylls and vitamin B12, share porphobilinogen as a common precursor.

It is involved in the second step of the metabolism of porphyrin.


A deficiency of porphobilinogen synthase is usually acquired (rather than hereditary) and and can be caused by heavy metal poisoning, especially lead poisoning, as the enzyme is very susceptible to inhibition by heavy metals.[1]

Hereditary insufficiency of porphobilinogen synthase is called porphobilinogen synthase (or ALA dehydratase) deficiency poprhyria. It is an extremely rare cause of porphyria,[2] with less than 10 cases ever reported.[3]

Heme synthesis—note that some reactions occur in the cytoplasm and some in the mitochondrion (yellow)

Lead poisoning works on the cellular level by binding to this enzyme, rendering it useless.


  1. ^ ALA dehydratase reaction, from NetBiochem at the University of Utah. Last modified 1/5/95
  2. ^ Jaffe EK, Stith L (February 2007). "ALAD porphyria is a conformational disease". Am. J. Hum. Genet. 80 (2): 329–37. doi:10.1086/511444. PMC 1785348. PMID 17236137. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1785348. Retrieved 2008-12-10. 
  3. ^ Overview of the Porphyrias at The Porphyrias Consortium (a part of NIH Rare Diseases Clinical Research Network (RDCRN)) Retrieved June 2011

External links

Wikimedia Foundation. 2010.

См. также в других словарях:

  • Porphobilinogen-Synthase — Δ Aminolävulinsäure Dehydratase Vorhandene Strukturdaten: 1E51 …   Deutsch Wikipedia

  • porphobilinogen synthase — por·pho·bi·lin·o·gen syn·thase (por″fo bĭ linґo jən sinґthās) [EC] an enzyme of the lyase class that catalyzes the condensation of two molecules of δ aminolevulinate to form porphobilinogen in the synthesis of… …   Medical dictionary

  • Porphobilinogen deaminase — (or hydroxymethylbilane synthase) is an enzyme involved in the third step of the metabolism of porphyrin, converting porphobilinogen into hydroxymethyl bilane. The enzyme has the unique cofactor dipyrromethane. Defective activity of this enzyme… …   Wikipedia

  • Porphobilinogen-Desaminase — Vorhandene Strukturdaten …   Deutsch Wikipedia

  • porphobilinogen — A porphyrin precursor of porphyrinogens, porphyrins, and heme; found in the urine in large quantities in cases of acute or congenital porphyria. p. synthase a liver enzyme …   Medical dictionary

  • porphobilinogen deaminase — por·pho·bi·lin·o·gen de·am·in·ase (por″fo bĭ linґə jən de amґin ās) hydroxymethylbilane synthase …   Medical dictionary

  • Cystathionine beta synthase — Structure of human cystathionine beta synthase.[1] …   Wikipedia

  • hydroxymethylbilane synthase — hy·droxy·meth·yl·bil·ane syn·thase (hi drok″se meth″əl bilґān sinґthās) [EC] an enzyme of the transferase class that catalyzes the deamination and condensation of four molecules of porphobilinogen to form a… …   Medical dictionary

  • Dihydropteroate synthase — Tetrahydrofolate synthesis pathway Identifiers EC number …   Wikipedia

  • uroporphyrinogen-III synthase — uro·por·phy·rin·o·gen III syn·thase (u″ro por″fə rinґə jən sinґthās) [EC] an enzyme of the lyase class that acts concertedly with hydroxymethylbilane synthase to convert porphobilinogen to uroporphyrinogen …   Medical dictionary

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