A series of enzymes catalyze the reaction 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.
-What is substance X?
A) a coenzyme
B) an allosteric inhibitor
C) a substrate
D) an intermediate
E) the product

Question

Quizplus · Accepted Answer

Substance X is the substrate that is converted to Y by the enzyme.

Answer: B
 Product A binding to the enzyme at a position remote from its active site indicates that it is an allosteric inhibitor, as it is affecting the enzyme's activity through an allosteric site rather than directly at the active site.

A Series of Enzymes Catalyze the Reaction X → Y