3-methyl-2-oxobutanoate dehydrogenase

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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 $\rightleftharpoons$ [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. The systematic name of this enzyme class is 3-methyl-2-oxobutanoate:[dihydrolipoyllysine-residue (2-methylpropanoyl)transferase]-lipoyllysine 2-oxidoreductase (decarboxylating, acceptor-2-methylpropanoylating). Other names in common use include (2-methylpropanoyl-transferring), 2-oxoisocaproate dehydrogenase, 2-oxoisovalerate (lipoate) dehydrogenase, 3-methyl-2-oxobutanoate dehydrogenase (lipoamide), 3-methyl-2-oxobutanoate:lipoamide oxidoreductase (decarboxylating, and acceptor-2-methylpropanoylating), alpha-keto-alpha-methylvalerate dehydrogenase, alpha-ketoisocaproate dehydrogenase, alpha-ketoisocaproic dehydrogenase, alpha-ketoisocaproic-alpha-keto-alpha-methylvaleric dehydrogenase, alpha-ketoisovalerate dehydrogenase, alpha-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 alpha-keto acid dehydrogenase, branched-chain alpha-oxo acid dehydrogenase, branched-chain keto acid dehydrogenase, branched-chain ketoacid dehydrogenase, dehydrogenase, 2-oxoisovalerate (lipoate), and dehydrogenase, branched chain alpha-keto acid. This enzyme participates in valine, leucine and isoleucine degradation. It employs one cofactor, thiamin diphosphate.

1 Structural studies
2 References
3 External links
- 3.1 Gene Ontology (GO) codes

[edit] Structural studies

As of late 2007, 29 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.

[edit] References

IUBMB entry for 1.2.4.4
BRENDA references for 1.2.4.4 (Recommended.)
PubMed references for 1.2.4.4
PubMed Central references for 1.2.4.4
Google Scholar references for 1.2.4.4
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: 3526–31. 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: 1198–203. PMID 5689906.
Danner DJ, Lemmon SK, Besharse JC, Elsas LJ 2nd (1979). "Purification and characterization of branched chain alpha-ketoacid dehydrogenase from bovine liver mitochondria". J. Biol. Chem. 254: 5522–6. 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: 4881–5. PMID 283398.
Perham RN (2000). "Swinging arms and swinging domains in multifunctional enzymes: catalytic machines for multistep reactions". Annu. Rev. Biochem. 69: 961–1004. PMID 10966480.