Day 106 MCAT Practice Question

The principles of Michaelis-Menten kinetics describe the relationship

between enzymes, which are protein molecules that catalyze various chemical

reactions, and different inhibitors capable of affecting enzyme activity.

An uncompetitive inhibitor works by binding not to the enzyme’s active site (where

substrate normally binds), but instead to an allosteric site distinct from the active

site. Typically, when uncompetitive inhibitors bind to allosteric sites, they cause

a change in the conformation of the enzyme’s physical structure such that the

substrate can no longer bind and undergo the reaction catalyzed by the enzyme.

This ultimately decreases the Vmax or the maximum velocity of the reaction while

Km, or the concentration at which ½ Vmax occurs, also decreases. For this reason,

Answer D is correct.