δ-aminolevulinate synthase
| 5-aminolevulinate synthase, unspecific | ||
|---|---|---|
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| Ribbon model (tetramer) of the ALAS of Rhodobacter , according to PDB 2BWN | ||
| Properties of human protein | ||
| Mass / length primary structure | 584 amino acids | |
| Secondary to quaternary structure | Homodimer | |
| Cofactor | Pyridoxal phosphate | |
| Isoforms | 2 | |
| Identifier | ||
| Gene name | ALAS1 | |
| External IDs | ||
| Enzyme classification | ||
| EC, category | 2.3.1.37 , transferase | |
| Substrate | Succinyl-CoA + glycine | |
| Products | 5-aminolevulinate + CoA + CO 2 | |
| Occurrence | ||
| Homology family | ALAS | |
| Parent taxon | Creature | |
The δ-aminolevulinate synthase ( δ-ALAS ) is a mitochondrial enzyme that is found in hepatocytes and erythroblasts . There are two isoenzymes , one that occurs ubiquitously (gene: ALAS1 ) and one that is specific for erythroblasts (gene: ALAS2 ). The enzyme catalyzes the reaction of succinyl-CoA from the citric acid cycle with the amino acid glycine to form δ-aminolevulinate with the elimination of CO 2 . This reaction is the rate-limiting step in heme biosynthesis . The reaction is dependent on pyridoxal phosphate . The δ-aminolevulinate synthase is inhibited by heavy metals such as lead and by heme itself as the end product of the heme biosynthetic pathway.
A defect in the ALAS2 gene leads to a (very rare) chromosome X -linked sideroblastic anemia . This leads to iron accumulation in the mitochondria of the bone marrow cells.
