Paper 2 · enzyme inhibition
In competitive inhibition, the inhibitor competes with the substrate for the enzyme's active site. At a sufficiently high substrate concentration, the reaction rate can eventually reach the same ___ as the uninhibited enzyme, because excess substrate molecules out-compete the inhibitor for the active site.
Model answer
maximum rate
Also accepted: Vmax, maximum reaction rate, maximum velocity, max rate
Explanation: Because a competitive inhibitor binds reversibly at the same site as the substrate, adding enough substrate means substrate molecules occupy the active site far more often than the inhibitor does, so the enzyme can still reach its normal maximum rate (Vmax), even though more substrate is needed to get there.
Derived from ZIMSEC Biology Paper 2, June 2006, Q1
