3-methyl-2-oxobutanoate Dehydrogenase

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 + lipoyllysine 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.