EC Number |
Reaction |
Reference |
---|
1.2.4.4 | 3-methyl-2-oxobutanoate + [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] lipoyllysine = [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] S-(2-methylpropanoyl)dihydrolipoyllysine + CO2 + 2 H+ |
- |
- |
1.2.4.4 | 3-methyl-2-oxobutanoate + [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] lipoyllysine = [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] S-(2-methylpropanoyl)dihydrolipoyllysine + CO2 + 2 H+ |
residues His146beta' and His291alpha of E1b component are essential for catalysis |
656171 |
1.2.4.4 | 3-methyl-2-oxobutanoate + [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] lipoyllysine = [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] S-(2-methylpropanoyl)dihydrolipoyllysine + CO2 + 2 H+ |
substrate recognition and reaction mechanism |
656230 |
1.2.4.4 | 3-methyl-2-oxobutanoate + [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] lipoyllysine = [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] S-(2-methylpropanoyl)dihydrolipoyllysine + CO2 + 2 H+ |
substrate recognition and reaction mechanism, involving residues Gly131beta-Gln131beta, Phe66alpha, Tyr86beta, Tyr95alpha, Met128alpha, His131alpha of component E1 |
-, 656534 |
1.2.4.4 | 3-methyl-2-oxobutanoate + [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] lipoyllysine = [dihydrolipoyllysine-residue (2-methylpropanoyl)transferase] S-(2-methylpropanoyl)dihydrolipoyllysine + CO2 + 2 H+ |
the multienzyme complex catalyzes a thiamine diphosphate- and Mg2+-dependent oxidative decarboxylation of branched-chain keto acids with the formation of branched-chain acyl-CoA and reduction of NAD+ to NADH: R1R2CHCOCOOH + NAD+ + CoASH = R1R2CHCO-S-CoA + NADH + CO2, component E1 (EC 1.2.4.4, branched-chain keto acid dehydrogenase), component E2 (no EC number, branched-chain acyltransferase), component E3 (EC 1.8.1.4, dihydrolipoamide dehydrogenase), partial reactions catalyzed by the multienzyme complex: 1. R1R2CHCOCOOH + E1-(thiamine diphosphate) = E1-(thiamine diphosphate)-COHCHR1R2 + CO2, 2. E1-(thiamine diphosphate)-COHCHR1R2 + lipoyl-E2 = R1R2CHCO-SCoA + dihydrolipoyl-E2, 4. dihydrolipoyl-E2 + NAD+ = lipoyl-E2 + NADH, the multienzyme complex also contains small amounts of a specific kinase and a specific phosphatase which modulate the activity of E1 by phosphorylation and dephosphorylation |
349045 |