A series of enzymes catalyse the reactions in the metabolic pathway X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. With respect to the enzyme that converts X to Y, substance A functions as ________.
A) an allosteric inhibitor
B) the substrate
C) an intermediate
D) a competitive inhibitor

Question

Quizplus · Accepted Answer

Product A binds to the enzyme that converts X to Y at a position remote from its active site, indicating that it functions as an allosteric inhibitor. This type of inhibitor binds to a site on the enzyme that is different from the active site and induces a conformational change that decreases the enzyme's activity. The fact that it does not bind to the active site excludes the possibility of it being a substrate or a competitive inhibitor. It is also not an intermediate, as intermediates are molecules that are formed and consumed during the course of a reaction.

A Series of Enzymes Catalyse the Reactions in the Metabolic