Question

The inhibition of succinic dehydrogenase by malonate is an example of

• A. Competitive inhibition
• B. Non competitive inhibition
• C. Allosteric inhibition
• D. Enzyme repression

Answer 1

The correct option is A Competitive inhibition

Enzyme inhibitors are molecular agents that interfere with catalysis, slowing or halting enzymatic reactions. One common type of reversible inhibition is called as competitive. A competitive inhibitor competes with the substrate for the active site of an enzyme. While the inhibitor (I) occupies the active site it prevents binding of the substrate to the enzyme. Many competitive inhibitors are compounds that resemble the substrate and combine with the enzyme to form an EI complex, but without leading to catalysis. Even fleeting combinations of this type will reduce the efficiency of the enzyme. Competitive inhibition can be analyzed quantitatively by steady-state kinetics. Because the inhibitor binds reversibly to the enzyme, the competition can be biased to favor the substrate simply by adding more substrate. When [S] far exceeds [I], the probability that an inhibitor molecule will bind to the enzyme is minimized and the reaction exhibits a normal V${}_{max}$. However, the [S] at which reaction rate is half that of V${}_{max}$, the apparent K${}_m$, increases in the presence of inhibitor. One common example of competitive inhibition is inhibition of the enzyme succinate dehydrogenase by malonate.