How does a noncompetitive inhibitor decrease the rate of an enzyme-catalysed reaction?
A) by binding to the active site of the enzyme, thus preventing binding of the normal substrate
B) by binding to an allosteric site, thus changing the shape of the active site of the enzyme
C) by decreasing the free-energy change of the reaction catalysed by the enzyme
D) by binding to the substrate, thus changing its shape so that it no longer binds to the active site of the enzyme

Question

Quizplus · Accepted Answer

A noncompetitive inhibitor binds to an allosteric site on the enzyme, causing a conformational change that alters the shape and function of the active site. This means that even if the substrate can still bind to the active site, it will no longer be able to do so effectively, resulting in a decrease in the rate of the reaction. Noncompetitive inhibitors do not bind to the active site itself, nor do they affect the free-energy change of the reaction or the substrate's shape.

How Does a Noncompetitive Inhibitor Decrease the Rate of an Enzyme-Catalysed