pyruvate dehydrogenase complex

Question 1

Why is the structure of the mitochondria important?

Answer 1

The two membranes (Outer and Inner) will create an electron potential between each other. Electrical gradient as it’s more positive outside. This forces molecules to want to move into the inner membrane, allowing ATP to be generated.

Question 2

What is the main function of the PDH complex?

Answer 2

To convert pyruvate into Acetyl-CoA

Question 3

What is the PDH complex often known as?

Answer 3

This reaction is known as the 3,5,5 reaction, as there are 3 subunits (Enzymes) that catalyse 5 reactions and uses 5 cofactors.

Question 4

Is the PDH complex reversible?

Answer 4

This reaction has a ΔG=-33.4kJ/mol, making it a highly irreversible reaction, and the PDH complex is considered the first control point of the citric acid cycle.

Question 5

What are the regulators of the PDH complex?

Answer 5

This reaction complex is allosterically inhibited by high concentrations of ATP, acetyl-CoA, and NADH
This reaction complex is allosterically encouraged by high concentrations of ADP, and pyruvate.

Question 6

What are the different steps in the PDH complex? include enzymes and cofactors.

Answer 6

1) The first enzyme is Pyruvate dehydrogenase, which uses the cofactor TPP to remove the CO2 from the pyruvate, resulting in Hydroxyethyl TPP.
2) This next enzyme is Dihydrolipoyl transacetylase, which does a couple things. First oxidised lipoyllysine is reacted with Hydroxyethyl TPP to produce Acyl Lipoyllysine and TPP (Which returns to the original cycle in 1). This is then catalysed with the cofactor CoA-SH and lipoate to produce Acetyl – CoA and reduced lipoyllysine.
3) The final enzyme Dihydrolipoyl dehydrogenase is used to catalyse the reaction of FAD and reduced lipoyllysine (From cycle 2), which produces oxidised lipoyllysine and FADH2. The FADH2 then reacts with NAD+ to reproduce FAD to react with reduced lipoyllysine again, as well as producing NADH + H .