PDH Reaction

Question 1

PDH complex is located in ______

Makes

Answer 1

mitochondria

Acetyl-CoA and NADH

Question 2

What vitamin does coenzyme A have?

Answer 2

pantothenate

Question 3

List basic steps

Answer 3

1) Decarboxylation pyruvate (E1)
2) Transfer E1 to E2
3) Acetyl Transfer to CoA (E2)
4) Oxidation of E2 (E3)
5) Oxidation of E3

Question 4

Step 1: Decarboxylation pyruvate

Answer 4

Cofactor: Thiamine P. (TPP, vitamin B1)
Has ring N+ to stabilize carboanion
Hydrox-ethel group has carbons to be transferred

CO2 leave, 2C transferred

Question 5

Step 2: Transfer from E1 to E2

Answer 5

Lys- lipoamide prosthetic group
Regenerates TPP cofactor

Active portion: disulfide bond which accepts hydroxyethyl group.

Regenerates E1, oxidizes hydroxyethyl to acetyl group

Question 6

Step 3: Acetyl Transfer to CoA

Answer 6

E2 transfers acetyl to CoA
Lipamide reduced
Acetyl-CoA is high energy due to thioester

Question 7

Step 4: Oxidation of E2

Answer 7

E3 re-oxidizes E2 lipoamide group (restore disulfide bond by reducing it’s own bond

Question 8

Step 5: Oxidation of E3

Answer 8

E3 transfers electrons to NAD+ via FAD
Electrons move to FAD to form FADH2
Electrons move from FADH2 to NAD+ to form NADH and H+
E3 Restored to oxidized state

Question 9

How is flux through pyruvate dehydrogenase regulated?

Answer 9

Product inhibition:
inhibited by NADH and acetyl-CoA

(And hormone control)