Oxoglutarate dehydrogenase (aka α-ketoglutarate dehydrogenase) is an enzyme complex most commonly known for its role in the citric acid cycle.
Much like pyruvate dehydrogenase complex, this enzyme forms a complex composed of three components:
|E1||EC 18.104.22.168||oxoglutarate dehydrogenase||OGDH||thiamine pyrophosphate|
|E2||EC 22.214.171.124||dihydrolipoyl succinyltransferase||DLST||lipoic acid|
|E3||EC 126.96.36.199||dihydrolipoyl dehydrogenase||DLD||NAD+|
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
This enzyme participates in three different pathways:
- Citric acid cycle (KEGG link: MAP00020)
- Lysine degradation (KEGG link: MAP00310)
- Tryptophan metabolism (KEGG link: MAP00380)
The following values are from Azotobacter vinelandii (1):
- KM: 0.14 ± 0.04 mM
- Vmax : 9 ± 3 μmol.min-1.mg-1
Citric acid cycle
The reaction catalyzed by this enzyme in the citric acid cycle is:
This reaction proceeds in three steps:
- decarboxylation of α-ketoglutarate,
- and subsequent transfer to CoA, which forms the end product, succinyl CoA.
2-Oxo-glutarate dehydrogrenase is an autoantigen recognized in primary biliary cirrhosis, a form of acute liver failure. These antibodies appear to recognize oxidized protein that has resulted from inflamatory immune responses. Some of these inflamatory responses are explained by gluten sensitivity. Other mitochondrial autoantigens include pyruvate dehydrogenase and branched-chain alpha-keto acid dehydrogenase complex, which are antigens recognized by anti-mitochondrial antibodies.
- 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.