A series of enzymes catalyze 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 .

The question is incomplete as it does not have the option which are:

A. A coenzyme.

B. An allosteric inhibitor.

C. The substrate.

D. An intermediate.

E. A competitive inhibitor.

An allosteric inhibitor.

Explanation:

An allosteric inhibitor is a molecule which binds to the site other than the active site but inhibits the action of the Enzyme and thus the product.

The allosteric inhibitor is considered a non-competitive inhibitor which after binding to the enzyme cause some conformational changes which further changes the structure of the active site and thus substrate no longer binds the enzyme. This molecule thus inhibits the production.

Thus, An allosteric inhibitor is correct.