Uroporphyrinogen III decarboxylase
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| |
| UroD drawn from PDB 1URO. | |
| uroporphyrinogen decarboxylase
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| Identifiers | |
| Symbol | UROD |
| Entrez | 7389 |
| HUGO | 12591 |
| OMIM | 176100 |
| RefSeq | NM_000374 |
| UniProt | P06132 |
| Other data | |
| EC number | 4.1.1.37 |
| Locus | Chr. 1 p34 |
Uroporphyrinogen III decarboxylase (UroD) is a homodimeric enzyme (EC 4.1.1.37, PDB 1URO) which catalyzes the fifth step in heme biosynthesis: the elimination of carboxyl groups from the four acetate side chains of uroporphyrinogen III to yield coproporphyrinogen III.
At low substrate concentrations the reaction is believed to follow an ordered route, with the sequential removal of CO2 from the D, A, B, and C rings, whereas at higher substrate/enzyme levels a random route seems to be operative. The enzyme functions as a dimer in solution, and both the enzymes from human and tobacco have been crystallized and solved at good resolutions.
UroD is regarded as an unusual decarboxylase, since it performs decarboxylations without the intervention of any cofactors, unlike the vast majority of decarboxylases. Its mechanism has recently been proposed to proceed through substrate protonation by an arginine residue.
Silva & Ramos (2005) performed a detailed study of competing reaction mechanisms proposed for uroporphyrinogen decarboxylase.[1]
References
Metabolism: amino acid metabolism - porphyrin enzymes | |
|---|---|
| Porphyrin biosynthesis | initial mitochondrial: Aminolevulinic acid synthase - Porphobilinogen synthase
cytosolic: Porphobilinogen deaminase - Uroporphyrinogen III synthase - Uroporphyrinogen III decarboxylase - Coproporphyrinogen III oxidase terminal mitochondrial: Protoporphyrinogen oxidase - Ferrochelatase |
| Heme breakdown to bile | spleen: Heme oxygenase - Biliverdin reductase liver: UDP-glucuronosyltransferase |
| see also disorders, intermediates | |
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
