EC 1 - Oxidoreductases
EC 1.2 - Acting on the aldehyde or oxo group of donors
EC 1.2.1 - With NAD+ or NADP+ as acceptor
EC 1.2.1.25 - Branched-chain α-keto acid dehydrogenase system
IntEnz Enzyme Nomenclature
EC 1.2.1.25
Names
α-ketoisovalerate dehydrogenase
2-oxoisovalerate dehydrogenase (acylating)
branched-chain α-keto acid dehydrogenase complex
Reaction
- 3-methyl-2-oxobutanoate + CoA + NAD(+) = 2-methylpropanoyl-CoA + CO(2) + NADH
Comments:
This enzyme system catalyses the oxidative decarboxylation of branched-chain α-keto acids derived from L-leucine, L-isoleucine, and L-valine to branched-chain acyl-CoAs. It belongs to the 2-oxoacid dehydrogenase system family, which also includes EC 1.2.1.104, pyruvate dehydrogenase system, EC 1.2.1.105, 2-oxoglutarate dehydrogenase system, EC 1.4.1.27, glycine cleavage system, and EC 2.3.1.190, acetoin dehydrogenase system. With the exception of the glycine cleavage system, which contains 4 components, the 2-oxoacid dehydrogenase systems share a common structure, consisting of three main components, namely a 2-oxoacid dehydrogenase (E1), a dihydrolipoamide acyltransferase (E2), and dihydrolipoamide dehydrogenase (E3). The reaction catalysed by this system is the sum of three activities: EC 1.2.4.4, 3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring), EC 2.3.1.168, dihydrolipoyllysine-residue (2-methylpropanoyl)transferase, and EC 1.8.1.4, dihydrolipoyl dehydrogenase. The system also acts on (S)-3-methyl-2-oxopentanoate and 4-methyl-2-oxopentanoate.
Links to other databases
References
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Coenzyme A- and nicotinamide adenine dinucleotide-dependent branched chain α-keto acid dehydrogenase. I. Purification and properties of the enzyme from Bacillus subtilis.J. Biol. Chem. 244 : 4437-4447 (1969). [PMID: 4308861]
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Purification and characterization of branched chain alpha-keto acid dehydrogenase complex of bovine kidney.Proc. Natl. Acad. Sci. U.S.A. 75 : 4881-4885 (1978). [PMID: 283398]
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Studies on the regulation of the mitochondrial alpha-ketoacid dehydrogenase complexes and their kinases.Adv. Enzyme Regul. 37 : 271-293 (1997). [PMID: 9381974]
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Crystal structure of human branched-chain alpha-ketoacid dehydrogenase and the molecular basis of multienzyme complex deficiency in maple syrup urine disease.Structure 8 : 277-291 (2000). [PMID: 10745006]
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A trail of research from lipoic acid to alpha-keto acid dehydrogenase complexes.J. Biol. Chem. 276 : 38329-38336 (2001). [PMID: 11477096]
[EC 1.2.1.25 created 1972, modified 2019, modified 2020]