Delta-aminolevulinic acid dehydratase

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Identifiers
Aliases
External IDs	GeneCards: [1]
Orthologs
Species	Human	Mouse
Entrez	n/a	n/a
Ensembl	n/a	n/a
UniProt	n/a	n/a
RefSeq (mRNA)	n/a	n/a
RefSeq (protein)	n/a	n/a
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Wikidata
View/Edit Human

Delta-aminolevulinic acid dehydratase is an enzyme (EC 4.2.1.24) that in humans is encoded by the ALAD gene. It catalyzes the following reaction:

2 δ-aminolevulinic acid <math>\rightleftharpoons</math> porphobilinogen + 2 H₂O

The ALAD enzyme is composed of 8 identical subunits and catalyzes the condensation of 2 molecules of delta-aminolevulinate to form porphobilinogen (a precursor of heme, cytochromes and other hemoproteins). ALAD catalyzes the second step in the porphyrin and heme biosynthetic pathway; zinc is essential for enzymatic activity. ALAD enzymatic activity is inhibited by lead, beginning at blood lead levels that were once considered to be safe (<10 μg/dL) and continuing to correlate negatively across the range from 5 to 95 μg/dL. Inhibition of ALAD by lead leads to anemia primarily because it both inhibits heme synthesis and shortens the lifespan of circulating red blood cells, but also by stimulating the excessive production of the hormone erythropoietin, leading to inadequate maturation of red cells from their progenitors. A defect in the ALAD structural gene can cause increased sensitivity to lead poisoning and acute hepatic porphyria. Alternatively spliced transcript variants encoding different isoforms have been identified.

External links

• Human ALAD genome location and ALAD gene details page in the UCSC Genome Browser.

Further reading

• Bernard A, Lauwerys R (1988). "Metal-induced alterations of delta-aminolevulinic acid dehydratase". Ann. N. Y. Acad. Sci. 514: 41–7. doi:10.1111/j.1749-6632.1987.tb48759.x. PMID 3327436.
• Jaffe EK (2005). "The porphobilinogen synthase catalyzed reaction mechanism". Bioorg. Chem. 32 (5): 316–25. doi:10.1016/j.bioorg.2004.05.010. PMID 15381398.
• Roels HA, Buchet JP, Lauwerys RR, Sonnet J (1975). "Comparison of in vivo effect of inorganic lead and cadmium on glutathione reductase system and delta-aminolevulinate dehydratase in human erythrocytes". British journal of industrial medicine. 32 (3): 181–92. doi:10.1136/oem.32.3.181. PMC 1008057. PMID 1156566.
• Ishida N, Fujita H, Fukuda Y, et al. (1992). "Cloning and expression of the defective genes from a patient with delta-aminolevulinate dehydratase porphyria". J. Clin. Invest. 89 (5): 1431–7. doi:10.1172/JCI115732. PMC 443012. PMID 1569184.
• Dawson SJ, White LA (1992). "Treatment of Haemophilus aphrophilus endocarditis with ciprofloxacin". J. Infect. 24 (3): 317–20. doi:10.1016/S0163-4453(05)80037-4. PMID 1602151.
• Astrin KH, Kaya AH, Wetmur JG, Desnick RJ (1991). "RsaI polymorphism in the human delta-aminolevulinate dehydratase gene at 9q34". Nucleic Acids Res. 19 (15): 4307. doi:10.1093/nar/19.15.4307-a. PMC 328595. PMID 1678509.
• Wetmur JG, Kaya AH, Plewinska M, Desnick RJ (1991). "Molecular characterization of the human delta-aminolevulinate dehydratase 2 (ALAD2) allele: implications for molecular screening of individuals for genetic susceptibility to lead poisoning". Am. J. Hum. Genet. 49 (4): 757–63. PMC 1683158. PMID 1716854.
• Plewinska M, Thunell S, Holmberg L, et al. (1991). "delta-Aminolevulinate dehydratase deficient porphyria: identification of the molecular lesions in a severely affected homozygote". Am. J. Hum. Genet. 49 (1): 167–74. PMC 1683193. PMID 2063868.
• Potluri VR, Astrin KH, Wetmur JG, et al. (1987). "Human delta-aminolevulinate dehydratase: chromosomal localization to 9q34 by in situ hybridization". Hum. Genet. 76 (3): 236–9. doi:10.1007/BF00283614. PMID 3036687.
• Gibbs PN, Jordan PM (1986). "Identification of lysine at the active site of human 5-aminolaevulinate dehydratase". Biochem. J. 236 (2): 447–51. PMC 1146860. PMID 3092810.
• Wetmur JG, Bishop DF, Cantelmo C, Desnick RJ (1986). "Human delta-aminolevulinate dehydratase: nucleotide sequence of a full-length cDNA clone". Proc. Natl. Acad. Sci. U.S.A. 83 (20): 7703–7. doi:10.1073/pnas.83.20.7703. PMC 386789. PMID 3463993.
• Wetmur JG, Bishop DF, Ostasiewicz L, Desnick RJ (1986). "Molecular cloning of a cDNA for human delta-aminolevulinate dehydratase". Gene. 43 (1–2): 123–30. doi:10.1016/0378-1119(86)90015-6. PMID 3758678.
• Doss M, von Tiepermann R, Schneider J (1981). "Acute hepatic porphyria syndrome with porphobilinogen synthase defect". Int. J. Biochem. 12 (5–6): 823–6. doi:10.1016/0020-711X(80)90170-6. PMID 7450139.
• Kaya AH, Plewinska M, Wong DM, et al. (1994). "Human delta-aminolevulinate dehydratase (ALAD) gene: structure and alternative splicing of the erythroid and housekeeping mRNAs". Genomics. 19 (2): 242–8. doi:10.1006/geno.1994.1054. PMID 8188255.
• Akagi R, Yasui Y, Harper P, Sassa S (1999). "A novel mutation of delta-aminolaevulinate dehydratase in a healthy child with 12% erythrocyte enzyme activity". Br. J. Haematol. 106 (4): 931–7. doi:10.1046/j.1365-2141.1999.01647.x. PMID 10519994.
• Akagi R, Shimizu R, Furuyama K, et al. (2000). "Novel molecular defects of the delta-aminolevulinate dehydratase gene in a patient with inherited acute hepatic porphyria". Hepatology. 31 (3): 704–8. doi:10.1002/hep.510310321. PMID 10706561.
• Kervinen J, Jaffe EK, Stauffer F, et al. (2001). "Mechanistic basis for suicide inactivation of porphobilinogen synthase by 4,7-dioxosebacic acid, an inhibitor that shows dramatic species selectivity". Biochemistry. 40 (28): 8227–36. doi:10.1021/bi010656k. PMID 11444968.