Competitive Inhibition in Enzyme Kinetics

Steps:

• Identify inhibitor type: reversible competitive inhibitor binds to the enzyme's active site, competing with substrate.
• Analyze attachment: it directly occupies the active site, preventing substrate binding temporarily.
• Evaluate rate effect: inhibitor increases Km (apparent lower affinity), but Vmax remains unchanged as high substrate displaces inhibitor.
• Compare to experiment: with increasing substrate concentrations, maximum rate is unaffected, showing little overall effect on peak enzyme activity.

Why D is correct:

• Competitive inhibitors bind the active site (yes) and allow full Vmax recovery with excess substrate, per Michaelis-Menten kinetics, resulting in little effect on maximum rate.

Why the others are wrong:

• A: Incorrect; competitive inhibitors do attach to the active site.
• B: Incorrect; rate does not increase—inhibitor reduces rate at low substrate but max rate unchanged.
• C: Incorrect; competitive inhibitors attach to the active site and do not increase rate.

Final answer: D