Noncompetitive inhibition and excess substrate
An inhibitor binds an allosteric site on an enzyme with equal affinity whether or not substrate is bound. What happens when substrate concentration is greatly increased?
Answer C: explanation for every choice
A
Restoring Vmax with excess substrate is characteristic of competitive inhibition.
B
A lower apparent Km occurs in uncompetitive inhibition, where the inhibitor binds only the ES complex.
C
Correct. This is pure noncompetitive inhibition: the inhibitor removes functional enzyme, which substrate cannot overcome.
D
A higher apparent Km occurs in competitive inhibition. Equal binding to E and ES leaves Km unchanged.
TakeawayNoncompetitive: Vmax down, Km unchanged, not overcome by substrate.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb102.