A noncompetitive inhibitor decreases the rate of an enzyme reaction by ________.
A) binding at the active site of the enzyme
B) changing the shape of the enzyme's active site
C) changing the overall free-energy of the reaction
D) acting as a coenzyme for the reaction
E) decreasing the activation energy of the reaction

Question

Quizplus · Accepted Answer

A noncompetitive inhibitor binds to the allosteric site on the enzyme, which is a different site from the active site. This binding causes a conformational change in the enzyme's shape, which can make it difficult for the substrate to bind to the active site, decreasing the rate of the reaction. It does not affect the overall free-energy of the reaction, act as a coenzyme or decrease the activation energy of the reaction.

A Noncompetitive Inhibitor Decreases the Rate of an Enzyme Reaction