Question

Which one of the following statements is INCORRECT for competitive inhibition in an enzyme catalysed reaction?

• A. Apparent \( K_m \) increases
• B. Apparent \( V_{\text{max}} \) decreases
• C. Inhibitor binds to the active site
• D. Inhibition decreases with an increase in [S]

Hint:

In competitive inhibition, \( V_{\text{max}} \) remains unchanged, but \( K_m \) appears to increase.

Answer 1

The Correct Option is B

Step 1: Understanding competitive inhibition.
In competitive inhibition, the inhibitor competes with the substrate for binding to the enzyme's active site.
Step 2: Analyzing the effects.
- (A) Apparent \( K_m \) increases: This is correct. Competitive inhibition increases the apparent \( K_m \) because more substrate is required to reach the same reaction rate.
- (B) Apparent \( V_{\text{max}} \) decreases: This is incorrect. Competitive inhibition does not affect \( V_{\text{max}} \); it can still be reached by increasing the concentration of the substrate.
- (C) Inhibitor binds to the active site: This is correct. The inhibitor competes with the substrate for the active site.
- (D) Inhibition decreases with an increase in [S]: This is correct. Increasing substrate concentration can overcome the inhibition.
Step 3: Conclusion.
Thus, the incorrect statement is (B) Apparent \( V_{\text{max}} \) decreases, making it the correct answer.