Pyruvate Dehydrogenase

Question 1

Where is pyruvate dehydrogenase localized?

Answer 1

The mitochondrial matrix

Question 2

In what conditions is pyruvate transported into the mitochondria for aerobic respiration?

Answer 2

Presence of both mitochondria and oxygen

Question 3

How is pyruvate transported from the cytoplasm to the mitochondrial matrix?

Answer 3

The mitochondrial pyruvate carrier (MPC)

Question 4

What cells lack mitochondria?

Answer 4

RBC and cells in the lens of the eye

Question 5

What are the 2 major highlights of the pyruvate dehydrogenase reaction?

Answer 5

1. Two carbons are transferred from Pyruvate to Acetyl-CoA

2. Electrons end up on NADH, the mobile electron carrier

Question 6

What enzyme is the cofactor thiamine pyrophosphate (TPP) associated with?

Answer 6

E1

Question 7

What enzyme is the cofactor lipoic acid (lipoamide) associated with?

Answer 7

E2 (via lysine)

Question 8

What enzyme is the cofactor CoA associated with?

Answer 8

E2

Question 9

What enzyme is the cofactor FAD associated with?

Answer 9

E3

Question 10

What enzyme is the cofactor NAD+ associated with?

Answer 10

E3

Question 11

Is it harder to rip electrons out of an alpha-keto acid or beta-keto acid?

Answer 11

alpha-keto acid

Question 12

Name an example of a beta-keto acid

Answer 12

Isocitrate

Question 13

Name an example of an alpha-keto acid

Answer 13

Pyruvate

Question 14

What is the role of the thiazolium ring in TPP?

Answer 14

It acts as an electron sink to stabilize both TPP carbanion and hydroxyethyl-TPP