A competitive inhibitor is a molecule that competes with the substrate for binding to the enzyme's active site. When a competitive inhibitor is present, it can bind to the enzyme and prevent the substrate from binding, thereby reducing the rate of the enzyme-catalyzed reaction. The effect of a competitive inhibitor on the Michaelis-Menten constant Km and maximum velocity Vmax can be understood by analyzing the enzyme kinetics.In the presence of a competitive inhibitor, the apparent Km Km' of the enzyme-catalyzed reaction increases, while the Vmax remains unchanged. This is because the competitive inhibitor increases the concentration of substrate required to achieve half of the maximum velocity Vmax/2 . The mathematical relationship between the apparent Km Km' and the inhibitor concentration [I] can be described by the following equation:Km' = Km 1 + [I] / Ki where Km is the Michaelis-Menten constant in the absence of the inhibitor, Km' is the apparent Km in the presence of the inhibitor, [I] is the concentration of the competitive inhibitor, and Ki is the inhibition constant, which represents the affinity of the inhibitor for the enzyme.As the concentration of the competitive inhibitor increases, the apparent Km Km' also increases, indicating that the enzyme's affinity for the substrate decreases. This is because the competitive inhibitor competes with the substrate for binding to the enzyme's active site, making it more difficult for the substrate to bind and form the enzyme-substrate complex.However, the maximum velocity Vmax of the enzyme-catalyzed reaction remains unchanged in the presence of a competitive inhibitor. This is because the competitive inhibitor does not affect the enzyme's catalytic efficiency once the substrate is bound to the enzyme. The Vmax can still be reached if the substrate concentration is high enough to outcompete the inhibitor for binding to the enzyme's active site.In summary, the concentration of a competitive inhibitor affects the Michaelis-Menten constant Km by increasing the apparent Km Km' , while the maximum velocity Vmax remains unchanged. The relationship between the apparent Km Km' and the inhibitor concentration [I] can be described by the equation:Km' = Km 1 + [I] / Ki