TCA, Anapleurotic Rxn

Question 1

Pt has lactic acidemia and reduced activity of alpha ketoglutarate dehydrogenase activity. What protein is likely to have a single enzymatic mutation to cause this?

Answer 1

The E3 subunit of pyruvate dehydrogenase, the dihydrolipoyl DH with bound FAD, is shared among all the alpha keto acid DH’s. Both pyruvate DH and alpha ketoglurate DH activity would be defective. Lead to accumulation of pyruvate, which would be converted to lactate, more lactate in blood and drop in pH

Question 2

Pt with thiamine deficiency had fatigue and muscle cramps. Cramps are related to accumulation of metabolic acids. What metabolic acid would accumulate with a thiamine deficiency?

Answer 2

Pyruvic acid or alpha ketoglutarate. TTP is the coenzyme for alpha ketoglutarate and pyruvate DH complexes.

Question 3

Succinate DH differs from all other enzymes in the TCA cycle because it is the only enzyme that is……?

Answer 3

Embedded in the inner mitochondrial membrane. Other enzymes are in the mitochondrial matrix.

Question 4

During exercise stimulation of the TCA cycle results in what?

Answer 4

Stimulation of the flux through several enzymes by a decrease NADH/NAD+ ratio. NADH decreases in exercise to generate energy for exercise.

Question 5

A deficiency of what compound would lead to an inability to produce coenzyme A

Answer 5

Pantothenate, its the vitamin precursor of CoA.
Niacin is precursor to NAD
Riboflavin is the precursor to FAD and FMN

Question 6

One of the big roles of the TCA cycle is to make reduced cofactors for ATP production from oxidative phosphorylation. What is the compound that donates the net 8 e’s to the cofactors?

Answer 6

Acetyl-CoA. It’s converted to two molecules of CO2. 8 e’s with the two carbons of Acetylene CoA are removed and put in 3 molecules of NADH and one FAD(2H).