Oxoglutarate dehydrogenase
From Wikipedia, the free encyclopedia
| 2-oxoglutarate dehydrogenase E1 component (α-Ketoglutarate dehydrogenase) | |
|---|---|
| Symbol(s): | OGDH |
| Other names: | Alpha-ketoglutarate dehydrogenase |
| Genetic data | |
| Locus: | Chr. 7 p13-p11.2 |
| Gene type: | protein coding |
| Protein Structure/Function | |
| Molecular Weight: | 115942 (Da) |
| Protein type: | Enzyme: Dehydrogenase |
| Functions: | converts Alpha ketoglutarate to succinyl CoA |
| Domains: | Transketolase central region, Dehydrogenase E1 component |
| Other | |
| Taxa expressing: | Homo sapiens; homologs: ubiquitous among oxidatively respiring organisms |
| Cell types: | ubiquitous among aerobic cells |
| Subcellular localization: | mitochondrion, mitochondrial matrix |
| Pathway(s): | Citric acid cycle, Lysine degradation, Tryptophan metabolism |
| Enzymatic Data | |
| Catalytic activity: | 2-oxoglutarate + [dihydrolipoyllysine-residue succinyltransferase] lipoyllysine = [dihydrolipoyllysine-residue succinyltransferase] S-succinyldihydrolipoyllysine + CO(2) |
| Cofactor(s): | Thiamine pyrophosphate |
| Enzyme Regulation: | Catabolite repressed |
| Medical/Biotechnological data | |
| Diseases: | Alpha-Ketoglutarate Dehydrogenase Deficiency |
| Database Links | |
| EC number: | 1.2.4.2 |
| Codes: | EntrezGene 4967; Mendelian Inheritance in Man (OMIM) 203740; RefSeq NM_001003941; UniProt Q02218 |
Oxoglutarate dehydrogenase (aka α-ketoglutarate dehydrogenase) is an enzyme (EC 1.2.4.2) most commonly known for its role in the citric acid cycle. Much like pyruvate dehydrogenase, this enzyme forms a complex composed of three components: E1, E2 and E3, which use thiamine pyrophosphate, lipoic acid and FAD as coenzymes, respectively. In fact three classes of thesse multienzyme complexes have been characterized, one specific for pyruvate, a second specific for 2-oxoglutarate and a third specific branched-chain α-keto acids.
Contents |
[edit] Properties
[edit] Nomenclature and classification
The official name of this enzyme is oxoglutarate dehydrogenase (OGDC) although it is also commonly known as α-ketoglutarate dehydrogenase (AKGDH).
- CAS: 9031-02-1
[edit] Metabolic pathways
This enzyme participates in three different pathways:
- Citric acid cycle (KEGG link: MAP00020)
- Lysine degradation (KEGG link: MAP00310)
- Tryptophan metabolism (KEGG link: MAP00380)
[edit] Kinetic properties
The following values are from Azotobacter vinelandii (1):
- KM: 0.14 ± 0.04 mM
- Vmax : 9 ± 3 μmol.min-1.mg-1
[edit] Citric acid cycle
[edit] Reaction
The reaction catalyzed by this enzyme in the citric acid cycle is:
- α-ketoglutarate + NAD+ + CoA → Succinyl CoA + CO2 + NADH
This reaction proceeds in three steps: decarboxylation of α-ketoglutarate, oxidation and subsequent transfer to CoA, which forms the end product, succinyl CoA. ΔG°' for this reaction is -7.2 kcal mol-1.
[edit] Regulation
Oxoglutarate dehydrogenase is a key control point in the citric acid cycle. It is inhibited by its products, succinyl CoA and NADH. A high energy charge in the cell will also be inhibitive.
[edit] References
- Bunik V, Westphal AH, de Kok A: Kinetic properties of the 2-oxoglutarate dehydrogenase complex from Azotobacter vinelandii evidence for the formation of a precatalytic complex with 2-oxoglutarate. Eur J Biochem 2000; 267(12): 3583-91. PMID 10848975.
