EC - Branched-chain α-keto acid dehydrogenase system

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IntEnz Enzyme Nomenclature


Accepted name:
branched-chain α-keto acid dehydrogenase system
Other names:
2-oxoisovalerate dehydrogenase
α-ketoisovalerate dehydrogenase
2-oxoisovalerate dehydrogenase (acylating)
branched-chain α-keto acid dehydrogenase complex
Systematic name:
3-methyl-2-oxobutanoate:NAD+ 2-oxidoreductase (CoA-methyl-propanoylating)



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, pyruvate dehydrogenase system, EC, 2-oxoglutarate dehydrogenase system, EC, glycine cleavage system, and EC, 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, 3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring), EC, dihydrolipoyllysine-residue (2-methylpropanoyl)transferase, and EC, dihydrolipoyl dehydrogenase. The system also acts on (S)-3-methyl-2-oxopentanoate and 4-methyl-2-oxopentanoate.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0047101
CAS Registry Number: 37211-61-3


  1. Namba, Y., Yoshizawa, K., Ejima, A., Hayashi, T. and Kaneda, T.
    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]
  2. Pettit, F. H., Yeaman, S. J., Reed, L. J.
    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]
  3. Harris, R. A., Hawes, J. W., Popov, K. M., Zhao, Y., Shimomura, Y., Sato, J., Jaskiewicz, J., Hurley, T. D.
    Studies on the regulation of the mitochondrial alpha-ketoacid dehydrogenase complexes and their kinases.
    Adv. Enzyme Regul. 37 : 271-293 (1997). [PMID: 9381974]
  4. Evarsson, A., Chuang, J. L., Wynn, R. M., Turley, S., Chuang, D. T., Hol, W. G.
    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]
  5. Reed, L. J.
    A trail of research from lipoic acid to alpha-keto acid dehydrogenase complexes.
    J. Biol. Chem. 276 : 38329-38336 (2001). [PMID: 11477096]

[EC created 1972, modified 2019, modified 2020]