IUBMB Enzyme Nomenclature


Accepted name: 3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring)

Reaction: 3-methyl-2-oxobutanoate + [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] lipoyllysine = [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] S-(2-methylpropanoyl)dihydrolipoyllysine + CO2

For diagram of reaction click here.

Glossary: dihydrolipoyl group
thiamine diphosphate

Other name(s):2-oxoisocaproate dehydrogenase; 2-oxoisovalerate (lipoate) dehydrogenase; 3-methyl-2-oxobutanoate dehydrogenase (lipoamide); 3-methyl-2-oxobutanoate:lipoamide oxidoreductase (decarboxylating and acceptor-2-methylpropanoylating); α-keto-α-methylvalerate dehydrogenase; α-ketoisocaproate dehydrogenase; α-ketoisocaproic dehydrogenase; α-ketoisocaproic-α-keto-α-methylvaleric dehydrogenase; α-ketoisovalerate dehydrogenase; α-oxoisocaproate dehydrogenase; BCKDH; BCOAD; branched chain keto acid dehydrogenase; branched-chain (-2-oxoacid) dehydrogenase (BCD); branched-chain 2-keto acid dehydrogenase; branched-chain 2-oxo acid dehydrogenase; branched-chain α-keto acid dehydrogenase; branched-chain α-oxo acid dehydrogenase; branched-chain keto acid dehydrogenase; branched-chain ketoacid dehydrogenase; dehydrogenase, 2-oxoisovalerate (lipoate); dehydrogenase, branched chain α-keto acid

Systematic name: 3-methyl-2-oxobutanoate:[dihydrolipoyllysine-residue (2-methylpropanoyl)transferase]-lipoyllysine 2-oxidoreductase (decarboxylating, acceptor-2-methylpropanoylating)

Comments: Contains thiamine diphosphate. It acts not only on 3-methyl-2-oxobutanaoate, but also on 4-methyl-2-oxopentanoate and (S)-3-methyl-2-oxopentanoate, so that it acts on the 2-oxo acids that derive from the action of transaminases on valine, leucine and isoleucine. It is a component of the multienzyme 3-methyl-2-oxobutanoate dehydrogenase complex in which multiple copies of it are bound to a core of molecules of EC, dihydrolipoyllysine-residue (2-methylpropanoyl)transferase, which also binds multiple copies of EC, dihydrolipoyl dehydrogenase. It does not act on free lipoamide or lipoyllysine, but only on the lipoyllysine residue in EC

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9082-72-8


1. Bowden, J.A. and Connelly, J.L. Branched chain α-keto acid metabolism. II. Evidence for the common identity of α-ketoisocaproic acid and α-keto-β-methyl-valeric acid dehydrogenases. J. Biol. Chem. 243 (1968) 3526-3531. [PMID: 5656388]

2.Connelly, J.L., Danner, D.J. and Bowden, J.A. Branched chain α-keto acid metabolism. I. Isolation, purification, and partial characterization of bovine liver α-ketoisocaproic:α-keto-β-methylvaleric acid dehydrogenase. J. Biol. Chem. 243 (1968) 1198-1203. [PMID: 5689906]

3. Danner, D.J., Lemmon, S.K., Beharse, J.C. and Elsas, L.J., II, Purification and characterization of branched chain α-ketoacid dehydrogenase from bovine liver mitochondria. J. Biol. Chem., 254, (1979) 5522-5526. [PMID: 447664]

4. Pettit, F.H., Yeaman, S.J. and Reed, L.J. Purification and characterization of branched chain α-keto acid dehydrogenase complex of bovine kidney. Proc. Natl. Acad. Sci. USA, 75, (1978) 4881-4885. [PMID: 283398]

5. Perham, R.N. Swinging arms and swinging domains in multifunctional enzymes: catalytic machines for multistep reactions. Annu. Rev. Biochem., 69, (2000) 961-1004. [PMID: 10966480]

[EC created 1972 (EC created 1972, incorporated 1978), modified 2003]

Return to EC 1.2.4 home page
Return to EC 1.2 home page
Return to EC 1 home page
Return to Enzymes home page
Return to IUBMB Biochemical Nomenclature home page