Question

In a metabolic pathway, succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, a substance that resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the amount of succinate molecules to those of malonic acid reduces the inhibitory effect of malonic acid. What role does malonic acid play with respect to succinate dehydrogenase?

In a metabolic pathway, succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, a substance that resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the amount of succinate molecules to those of malonic acid reduces the inhibitory effect of malonic acid. What role does malonic acid play with respect to succinate dehydrogenase?

Malonic acid is a competitive inhibitor.

Malonic acid blocks the binding of fumarate.

Malonic acid is a noncompetitive inhibitor.

Malonic acid is an allosteric regulator.

Answer 1

Solution:

Malonic Acid is a competitive inhibitor of the enzyme succinate dehydrogenase. It binds to the active site of the enzyme without reacting and so it competes with succinate which is the usual substrate of the enzyme.