Question: 112. Inhibition of Succinic dehydrogenase enzyme by malonate is a classical example of :
(2) Feedback inhibition
(1) Cofactor inhibition
(3) Competitive inhibition
(4) Enzyme activation
Answer: Option (3)
Explanation:
Succinic dehydrogenase is an enzyme that catalyzes the oxidation of succinate to fumarate in the Krebs cycle.
Malonate is a structural analogue of succinate, meaning it has a similar molecular structure to the substrate succinate.
Due to this structural similarity, malonate competes with succinate for binding at the active site of the enzyme.
When malonate binds to the active site, it prevents succinate from binding, thereby reducing the rate of the enzymatic reaction.
This type of inhibition, where the inhibitor competes with the substrate for the same active site, is known as competitive inhibition.
In competitive inhibition, the effect of the inhibitor can be reduced by increasing the concentration of the substrate.
Hence, inhibition of succinic dehydrogenase by malonate is a classical example of competitive inhibition.