How do non-competitive inhibitors affect enzymes?

Non-competitive inhibitors affect enzyme activity by binding to a different site on the enzyme, which is distinct from the active site. When the inhibitor binds, it causes a conformational change in the enzyme shape. This alteration affects the enzyme's overall activity, reducing its ability to catalyze the reaction, regardless of whether the substrate is present or not. This is a key characteristic of non-competitive inhibition: the inhibitor doesn't compete with the substrate for the active site, but rather modifies the enzyme in such a way that its effectiveness is diminished, leading to decreased reaction rates.

In contrast, binding to the active site, increasing substrate binding, or enhancing enzyme functionality does not accurately describe the role of non-competitive inhibitors. Non-competitive inhibitors decrease the maximum rate of reaction (Vmax) without affecting the affinity for the substrate (Km). Thus, understanding the precise mechanism of non-competitive inhibition is crucial for grasping how various inhibitors can modulate enzyme activity in biochemical pathways.