What is the primary effect of competitive inhibition on Km?

In the context of competitive inhibition, the primary effect on the Michaelis-Menten constant (Km) is that it increases. Competitive inhibitors work by binding to the active site of an enzyme, competing with the substrate for that binding spot. This means that higher concentrations of substrate are required to achieve the same rate of reaction when an inhibitor is present.

As a result of this competition, the apparent affinity of the enzyme for the substrate decreases, leading to an increase in Km. While the maximum reaction velocity (Vmax) remains unchanged under competitive inhibition, the higher Km indicates that a greater substrate concentration is needed to reach half of Vmax.

This concept helps in understanding enzyme kinetics and how inhibitors can alter the behavior of enzyme-substrate interactions, providing insights into drug design and enzyme regulation in metabolic pathways.