To understand the effect of different types of enzyme inhibition on Km and Vmax, it's important to know what these terms signify: Km (Michaelis constant) is a measure of the substrate concentration required for an enzyme to reach half its maximum reaction velocity (Vmax).
In competitive inhibition, an inhibitor competes with the substrate for binding to the active site of the enzyme. This results in an increase in Km because a higher substrate concentration is needed to reach the same reaction velocity as the inhibitor is blocking some of the active sites. However, Vmax remains unchanged because if enough substrate is added, it can outcompete the inhibitor, saturating the enzyme just as it would in the absence of the inhibitor.
Hence, the characteristic effects of competitive inhibition are:
Increased Km
Unchanged Vmax
This contrasts with other types of inhibition:
In noncompetitive inhibition, the inhibitor binds to an allosteric site rather than the active site, reducing Vmax without affecting Km, as the inhibitor reduces the number of active enzymes available regardless of substrate concentration.
In uncompetitive inhibition, the inhibitor binds only to the enzyme-substrate complex, decreasing both Km and Vmax proportionally, as it stabilizes the complex without competing with the substrate for the enzyme itself.
Thus, the correct answer is: Competitive inhibition.
