Final answer:
A noncompetitive allosteric antagonist binds to an enzyme at an allosteric site, not the active site, causing a change in shape that prevents the enzyme from binding to the substrate and decreases the enzyme's activity.
Step-by-step explanation:
A noncompetitive allosteric antagonist is a molecule that binds to an enzyme at a location other than the active site, known as an allosteric site. This binding induces a conformational change in the enzyme, altering the shape of the active site and decreasing the enzyme's affinity for its substrate. As a result, the substrate cannot bind effectively to the enzyme, impeding the enzyme's function.
This mode of inhibition is particularly efficient because a single inhibitor molecule can significantly affect the enzyme's activity, and this effect cannot be overcome by increasing the concentration of the substrate. Noncompetitive allosteric inhibition plays a vital role in regulating metabolic pathways through feedback mechanisms and can be exploited for drug development in various therapeutic applications.