Pyruvate Dehydrognase

Question 1

What are the 2 parts of PDC?

Answer 1

1. breakdown pyruvate which is a 3C molecule into a 2C molecule and CO2
2. to produce NADH

Question 2

What are the 3 enzymes of PDC?

Answer 2

E1: pyruvate dehydrogenase (TPP)
E2: dihydrolipolyl transacetylase (lipoate, CoA)
E3: dihydrolipolyl dehydrogenase (NAD, FAD)

Question 3

What are CoA and NAD?

Answer 3

cosubstrates (free to move around and interact)

Question 4

What are TPP, lipoate, and FAD?

Answer 4

prosthetic groups (covalently bound to enzyme)

Question 5

What happens in E1?

Answer 5

• decarboxylation
• acetyl transfer

TPP carbanion attacks pyruvate and then CO2 is released to form the acetyl-TPP complex

Question 6

What happens in E2?

Answer 6

-transacetylation

Acetyl group is transferred from TPP to lipoate. First the lipoate is attached to the acetyl-TPP complex. Then TPP part is removed and you are just left with the acetyl-dihydrolipoyl PdH complex.

Question 7

What happens in E3?

Answer 7

-regeneration of FAD and dihydrolipoyl

CoASH enters the system and forms Acetyl CoA.

Next dihydrolipoyl PdH is transformed back into lipoyl PdH and FAD is transformed into NADH2

Question 8

What is different between the PDH complex and the PDC complex?

Answer 8

They both start off with decarboxylation.

Then the acetyl TPP complex attacks a free H+

That molecule then breaks up into TPP-pDc and acetaldehyde with a free H+ floating around.