Question

In a biological reaction, 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. Select the correct identification of the molecules described in the reaction.

Answer 1

In the given example, malonic acid is the competitive inhibitor of succinate.

Step-by-step explanation:

- When a substance diminishes the velocity of an enzyme catalyzed reaction then it is called inhibitor.

- These inhibitors can bind to enzyme in a reversible or irreversible fashion.

- Reversible inhibitor binds to enzyme by non-covalent bonds.

- There are two types of enzyme inhibition: Competitive and non-competitive.

- Competitive inhibition: We use the term competitive if the inhibitor binds to enzyme reversibly at the same site as substrate would bind.

- Here in this example, both succinate and malonic acid have same binding site on enzyme i.e the active site. Since both can bind to the same site, inhibitor competes with the substrate for that site.

- By increasing the concentration of substrate, we can reverse the effect of competitive inhibitor.

- At a sufficiently high concentration of substrate, V-max can be achieved for the reaction. In the Michaelis-Mentens curve we can observe increase in the Km value in the presence of competitive inhibitor.