3-methyl-2-oxobutanoate dehydrogenase

In enzymology, a 3-methyl-2-oxobutanoate dehydrogenase 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.

Structural studies
As of late 2007, 29 structures have been solved for this class of enzymes, with PDB accession codes, , , , , , , , , , , , , , , , , , , , , , , , , , , , and.