Link Reaction

Question 1

Is the Link Reaction an Anaerobic or Aerobic process?

Answer 1

Aerobic

Question 2

What is the starting molecule in the Link Reaction?

Answer 2

Pyruvate

Question 3

What is the name of the complex that the Link Reaction takes place in?

Answer 3

Pyruvate Dehydrogenase complex

Question 4

How many carriers are involved in the pyruvate dehydrogenase complex?

Answer 4

3

Question 5

What’s the name of the first carrier in the pyruvate dehydrogenase complex?
And what is it a carrier for?

Answer 5

pyruvate dehydrogenase E1

TPP carrier

Question 6

WHatis the name of the second carrier in the pyruvate dehydrogenase complex and what is it a carrier for?

Answer 6

dihydrolipoyl transacetylase E2

lipoamide carrier

Question 7

WHat is the name of the final carrier in the pyruvate dehydrogenase complex and what is it a carrier for?

Answer 7

dihydrolipyl dehydrogenase E3

FAD carrier

Question 8

What is the main function of the link reaction?

Answer 8

transport into the matrix for the TCA cycle

Question 9

What types of regulation are involved in the regulation of E1?

Answer 9

phosphorylation and dephosphorylation

Question 10

What reaction occurs at E1? Is it reversible or irreversible?

Answer 10

Irreversible oxidative decarboxylation
Pyruvate to CO2 + E1TPP (E1 bound to pyruvate)
(decarboxylation on binding)

Question 11

What reaction occurs at E2?

Answer 11

acetyl group on E2 lipoamide thiol combines with CoA producing acetyl CoA

Question 12

What is the overall role of E3?

Answer 12

regeneration of oxidised lipoamide for use in E2

Question 13

What reactions occur at E3?

Answer 13

Converstion FADH to FAD via NAD+ to NADH

Question 14

Which carrier is the core of the complex?

Answer 14

E2

Question 15

Describe the structure of the E2 lipoamide carrier.

Answer 15

• Many trimer subunits forming a hollow cube

- Flexible linkages to lipoamide

Question 16

What are the products of the link reaction?

Answer 16

CO2
NADH + H+
Acetyl CoA