What impact does a competitive inhibitor have on an enzyme reaction?

A competitive inhibitor will alter the apparent Km of the reaction because it competes with the substrate for binding to the active site of the enzyme. In the presence of a competitive inhibitor, more substrate is required to reach half the maximum velocity (Vmax) of the enzyme reaction, which effectively increases the Km value (the Michaelis constant). This indicates that a higher concentration of substrate is necessary to overcome the inhibition and achieve the same level of enzyme activity that would be observed in the absence of the inhibitor. The Vmax remains unchanged because, if enough substrate is present, it can outcompete the inhibitor for binding to the active site, allowing the enzyme to reach its maximum catalytic potential. This dynamic highlights how the presence of a competitive inhibitor modifies the relationship between substrate concentration and reaction velocity, specifically by affecting the Km.