The Enzyme Database

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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 oxo-acid-dehydrogenase complexes, click here
Glossary: dihydrolipoyl group
thiamine diphosphate = 3-[(4-amino-2-methylpyrimidin-5-yl)methyl]-5-(2-diphosphoethyl)-4-methyl-1,3-thiazolium
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]
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