Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid.
-What is malonic acid's role with respect to succinate dehydrogenase?
A) It is a competitive inhibitor.
B) It blocks the binding of fumarate.
C) It is a noncompetitive inhibitor.
D) It is able to bind to succinate.
E) It is an allosteric regulator.

Question

Quizplus · Accepted Answer

Malonic acid is a competitive inhibitor of succinate dehydrogenase as it resembles its substrate (succinate) and can bind to the active site of the enzyme, preventing succinate from binding and the reaction from occurring. Increasing the concentration of succinate leads to more competition between succinate and malonic acid for binding to the active site, reducing the inhibitory effect of malonic acid.

Succinate Dehydrogenase Catalyzes the Conversion of Succinate to Fumarate