Which site does a non-competitive inhibitor bind to on an enzyme?

A non-competitive inhibitor binds to an allosteric site on an enzyme. This type of inhibitor interacts with an enzyme at a location other than the active site, leading to a conformational change that reduces the enzyme's activity. Because the active site remains available for substrate binding, the inhibitor affects the enzyme's performance without preventing substrate access.

The binding of the non-competitive inhibitor can occur whether the substrate is present or not, affecting the overall catalytic efficiency of the enzyme without altering the maximum reaction velocity (Vmax). Thus, even if the substrate can still bind, the reaction rate is hindered due to the altered enzyme structure.

In contrast, options that suggest binding to the active site, regulatory site, or substrate site do not accurately reflect the mechanism of non-competitive inhibition as they imply direct interference with substrate binding or enzyme regulation in a way that is inconsistent with how non-competitive inhibitors function.