Dihydrolipoyl dehydrogenase (E3)
Cofactors used
What it does, reaction by reaction
Pyruvate Oxidation / Link Reaction (Pyruvate Dehydrogenase Complex) Carbohydrate Metabolism · Mitochondrial matrix
Dihydrolipoamide + FAD → oxidized lipoamide + FADH2
Converts Dihydrolipoamide FAD into Oxidized lipoamide FADH2
› Notes
The E3 component, dihydrolipoyl dehydrogenase, reoxidizes reduced lipoamide using its tightly bound FAD prosthetic group. This reaction restores the oxidized lipoyl arm required for another catalytic cycle.
FADH2 + NAD+ → FAD + NADH + H+
Converts FADH2 NAD+ into FAD NADH H+
› Notes
E3 transfers reducing equivalents from FADH2 to NAD+, generating NADH. Together, the E1–E3 sequence constitutes PDC catalysis; the complex is the regulated, effectively rate-controlling entry point of pyruvate carbon into acetyl-CoA.
Pyruvate Dehydrogenase Complex (Link Reaction, connecting glycolysis to the TCA cycle) Energy Metabolism & Cellular Respiration · Mitochondrial matrix
Dihydrolipoamide-E2 + FAD → oxidized lipoamide-E2 + FADH2
Converts Dihydrolipoamide-E2 FAD into Oxidized lipoamide-E2 FADH2
› Notes
Required prosthetic group: tightly bound FAD; electrons are transferred from dihydrolipoamide to FAD.
FADH2 + NAD+ → FAD + NADH + H+
Converts FADH2 NAD+ into FAD NADH H+
› Notes
Required cofactor: NAD+. The summed PDC reaction is: pyruvate + CoA-SH + NAD+ → acetyl-CoA + CO2 + NADH + H+. It is irreversible and is a major regulatory/committed step for oxidative disposal of pyruvate.
Showing all 4 reactions.
What accelerates and inhibits it
Regulation is pathway-specific, so each context is listed separately
No regulation recorded for this enzyme in the source documents.
Recent literature
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