Reaction catalyzed by 3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring) (1.2.4.4)

		+			=			+
	3-methyl-2-oxopentanoate	+		[dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] lipoyllysine	=		[dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] S-(2-methylbutanoyl)dihydrolipoyllysine	+		CO2