CHEM 160 OXIDATIVE DECARBOXYLATION

pyruvate dehydrogenase complex.

Pyruvate is converted to Acetyl CoA through the action of

Oxidative Decarboxylation

- Irreversible oxidation process wherein the carboxyl group is removed as carbon dioxide.

substrate channeling.

Ø Process in which the Intermediate produced by one enzyme is transferred to the next without mixing or release on the solution.

Pyruvate dehydrogenase + thiamine pyrophosphate

Function: Oxidative phosphorylation of pyruvate

What is E1 and its co-factor and function

dihydrolipoyl transacetylase + lipoate, CoA

Function: Transfer of acetyl group to CoA

What is E2 and its co-factor and function

Dihydrolipoyl dehydrogenase + FAD, NAD+

Function: Regeneration of the oxidized form of lipoamide

What is E3 and its co-factor and function

1. Pyruvate reacts with bound TPP of E1.

Ø Decarboxylation to the hydroxyethyl derivative.

2. E1 transfers 2 electrons and acetyl group from TPP to the oxidized form of lipoamide in E2.

Ø Reduction by formation of a thioester bond (acetyl-dihydrolipoamide)

3. Transesterification of acetyl group to CoASH.

Ø Formation of reduced lipoamide.

4. E3 transfers 2H from reduced lipoamide to FAD, a prosthetic group of E3.

Ø Regenerates the oxidized lipoamide.

5. Reduced FAD is restored back using NAD.

Ø Enzymes are now ready for another round.

What happened to pyruvate dehydrogenase?