5hnr

Structural highlights

Disease

[HEM2_HUMAN] Defects in ALAD are the cause of acute hepatic porphyria (AHEPP) [MIM:612740]. A form of porphyria. Porphyrias are inherited defects in the biosynthesis of heme, resulting in the accumulation and increased excretion of porphyrins or porphyrin precursors. They are classified as erythropoietic or hepatic, depending on whether the enzyme deficiency occurs in red blood cells or in the liver. AHP is characterized by attacks of gastrointestinal disturbances, abdominal colic, paralysis, and peripheral neuropathy. Most attacks are precipitated by drugs, alcohol, caloric deprivation, infections, or endocrine factors.^{[1] [2] [3] [4] [5]}

Function

[HEM2_HUMAN] Catalyzes an early step in the biosynthesis of tetrapyrroles. Binds two molecules of 5-aminolevulinate per subunit, each at a distinct site, and catalyzes their condensation to form porphobilinogen.^{[6] [7]}

References

1. ↑ Ishida N, Fujita H, Fukuda Y, Noguchi T, Doss M, Kappas A, Sassa S. Cloning and expression of the defective genes from a patient with delta-aminolevulinate dehydratase porphyria. J Clin Invest. 1992 May;89(5):1431-7. PMID:1569184 doi:http://dx.doi.org/10.1172/JCI115732
2. ↑ Plewinska M, Thunell S, Holmberg L, Wetmur JG, Desnick RJ. delta-Aminolevulinate dehydratase deficient porphyria: identification of the molecular lesions in a severely affected homozygote. Am J Hum Genet. 1991 Jul;49(1):167-74. PMID:2063868
3. ↑ Sassa S, Ishida N, Fujita H, Fukuda Y, Noguchi T, Doss M, Kappas A. Cloning and expression of the defective genes in delta-aminolevulinate dehydratase porphyria: compound heterozygosity in this hereditary liver disease. Trans Assoc Am Physicians. 1992;105:250-9. PMID:1309003
4. ↑ Akagi R, Shimizu R, Furuyama K, Doss MO, Sassa S. Novel molecular defects of the delta-aminolevulinate dehydratase gene in a patient with inherited acute hepatic porphyria. Hepatology. 2000 Mar;31(3):704-8. PMID:10706561 doi:S0270913900700632
5. ↑ Jaffe EK, Stith L. ALAD porphyria is a conformational disease. Am J Hum Genet. 2007 Feb;80(2):329-37. Epub 2006 Dec 21. PMID:17236137 doi:10.1086/511444
6. ↑ Jaffe EK, Martins J, Li J, Kervinen J, Dunbrack RL Jr. The molecular mechanism of lead inhibition of human porphobilinogen synthase. J Biol Chem. 2001 Jan 12;276(2):1531-7. PMID:11032836 doi:10.1074/jbc.M007663200
7. ↑ Lawrence SH, Ramirez UD, Selwood T, Stith L, Jaffe EK. Allosteric inhibition of human porphobilinogen synthase. J Biol Chem. 2009 Dec 18;284(51):35807-17. doi: 10.1074/jbc.M109.026294. Epub . PMID:19812033 doi:10.1074/jbc.M109.026294