3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring)
2-oxoisovalerate dehydrogenase heterotetramer, Human
Identifiers
EC no.	1.2.4.4
CAS no.	9082-72-8
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

In enzymology, a 3-methyl-2-oxobutanoate dehydrogenase (EC 1.2.4.4) is an enzyme that catalyzes the chemical reaction

3-methyl-2-oxobutanoate + [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] lipoyllysine ${\displaystyle \rightleftharpoons }$ [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] S-(2-methylpropanoyl)dihydrolipoyllysine + CO₂

The 3 substrates of this enzyme are 3-methyl-2-oxobutanoate, dihydrolipoyllysine-residue (2-methylpropanoyl)transferase, and lipoyllysine, whereas its 3 products are dihydrolipoyllysine-residue (2-methylpropanoyl)transferase, S-(2-methylpropanoyl)dihydrolipoyllysine, and CO₂.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the aldehyde or oxo group of donor with a disulfide as acceptor.

This enzyme participates in valine, leucine and isoleucine degradation. It employs one cofactor, thiamin diphosphate. It is the E1 subunit of a catalytic complex.

As of late 2007, twenty-nine structures have been solved for this class of enzymes, with PDB accession codes 1DTW, 1OLS, 1OLU, 1OLX, 1U5B, 1UM9, 1UMB, 1UMC, 1UMD, 1V11, 1V16, 1V1M, 1V1R, 1WCI, 1X7W, 1X7X, 1X7Y, 1X7Z, 1X80, 2BEU, 2BEV, 2BEW, 2BFB, 2BFC, 2BFD, 2BFE, 2BFF, 2BP7, and 2J9F.

• Bowden JA, Connelly JL (1968). "Branched chain alpha-keto acid metabolism. II. Evidence for the common identity of alpha-ketoisocaproic acid and alpha-keto-beta-methyl-valeric acid dehydrogenases". J. Biol. Chem. 243 (12): 3526–31. doi:10.1016/S0021-9258(18)93339-9. PMID 5656388.
• Connelly JL, Danner DJ, Bowden JA (1968). "Branched chain alpha-keto acid metabolism. I. Isolation, purification, and partial characterization of bovine liver alpha-ketoisocaproic:alpha-keto-beta-methylvaleric acid dehydrogenase". J. Biol. Chem. 243 (6): 1198–203. doi:10.1016/S0021-9258(19)56972-1. PMID 5689906.
• Danner DJ, Lemmon SK, Besharse JC, Elsas LJ II (1979). "Purification and characterization of branched chain alpha-ketoacid dehydrogenase from bovine liver mitochondria". J. Biol. Chem. 254 (12): 5522–6. doi:10.1016/S0021-9258(18)50626-8. PMID 447664.
• Pettit FH, Yeaman SJ, Reed LJ (1978). "Purification and characterization of branched chain alpha-keto acid dehydrogenase complex of bovine kidney". Proc. Natl. Acad. Sci. U.S.A. 75 (10): 4881–5. Bibcode:1978PNAS...75.4881P. doi:10.1073/pnas.75.10.4881. PMC 336225. PMID 283398.
• Perham RN (2000). "Swinging arms and swinging domains in multifunctional enzymes: catalytic machines for multistep reactions". Annu. Rev. Biochem. 69 (1): 961–1004. doi:10.1146/annurev.biochem.69.1.961. PMID 10966480.