Question

9. Which of the listed enzymes of the TCA cycle is regulated by phosphorylation/dephosphorylation cycle ? :

a. isocitrate dehydrogenase b. succinate dehydrogenase c. malate dehydrogenase d. α-ketoglutarate dehydrogenase complex\}

c. citrate synthase

10. Name the enzyme catalyzing the following reaction:

a. PEP carboxykinase

b. pyruvate kinase

c. malic enzyme

d. pyruvate carboxylase

11. Name the enzyme that catalyzes the reaction:

glyoxylate +CH3CO-SCoA → malate + HSCoA

a. malate synthase

b. succinate thiokinase

c. aconitase

d. isocitrate

Answer 1

9. Option A is correct
Isocitrate dehydrogenase catalyzes the conversion of Isocitrate to Alpha-ketoglutarate
It is allosterically regulated by phosphorylation and dephosphorylation.

There are several kinases that phosphorylate Malate dehydrogenase as well.

10. Option A is correct
The given reaction is catalyzed by PEP-carboxykinase
Oxaloacetate + GTP <-----> PEP + CO₂ + GDP

11. Option A is correct
Malate synthase catalyzes the following reaction.
Acetyl CoA + Glyoxylate ------> L-Malate