Competitive inhibitors primarily affect which part of enzyme activity?

Competitive inhibitors primarily affect active site binding. These inhibitors are structurally similar to the substrate and compete with it for binding to the active site of the enzyme. When a competitive inhibitor is present, it binds to the active site, thereby preventing the substrate from accessing that site and undergoing the reaction.

This competitive interaction increases the apparent Km of the enzyme for its substrate, indicating that higher substrate concentrations are necessary to achieve half-maximal velocity since the substrate must compete with the inhibitor for binding. However, the maximum velocity (Vmax) remains unchanged, as the inhibition can be overcome by adding more substrate.

Understanding the role of competitive inhibitors in this way highlights their mechanism of action and influence on enzyme kinetics, specifically how they alter the binding dynamics at the active site without affecting other aspects of enzyme function, such as degradation, cofactor interactions, or product release.