What type of inhibitor changes the shape of an enzyme without entering the active site?

A noncompetitive inhibitor alters the shape of an enzyme, which in turn affects its activity, without binding directly to the active site. When a noncompetitive inhibitor binds to an enzyme at a separate site, it induces a conformational change that renders the enzyme less effective in catalyzing reactions, regardless of whether the substrate is present or not. This means that the substrate can still bind to the active site, but the enzymatic reaction is inhibited because the structure of the enzyme has been modified.

In contrast, a competitive inhibitor directly competes with the substrate for the active site, thereby blocking the substrate from binding, but does not change the enzyme's overall shape. Coenzymes are organic molecules that assist enzymes but do not inhibit them, while feedback regulators typically involve a process where the end product of a metabolic pathway inhibits an earlier step in the pathway but do not specifically refer to how they affect enzyme shape. Thus, noncompetitive inhibitors are unique in their ability to modify enzyme shape without interfering at the active site.