In competitive inhibition, how do the apparent Km and Vmax change?

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Multiple Choice

In competitive inhibition, how do the apparent Km and Vmax change?

In competitive inhibition, the inhibitor competes with the substrate for binding to the enzyme’s active site. This means you need more substrate to reach half-maximal velocity, so the apparent Km increases because the enzyme appears to have lower affinity for the substrate in the presence of the inhibitor. However, Vmax stays the same because, at high enough substrate concentrations, substrate can outcompete the inhibitor, allowing the enzyme to reach its full catalytic rate just as it would without inhibition. So the correct description is that the apparent Km increases while Vmax remains unchanged. The patterns described by the other options correspond to different types of inhibition (for example, noncompetitive inhibition lowers Vmax), which is why those scenarios don’t fit competitive inhibition.

In competitive inhibition, the inhibitor competes with the substrate for binding to the enzyme’s active site. This means you need more substrate to reach half-maximal velocity, so the apparent Km increases because the enzyme appears to have lower affinity for the substrate in the presence of the inhibitor. However, Vmax stays the same because, at high enough substrate concentrations, substrate can outcompete the inhibitor, allowing the enzyme to reach its full catalytic rate just as it would without inhibition. So the correct description is that the apparent Km increases while Vmax remains unchanged. The patterns described by the other options correspond to different types of inhibition (for example, noncompetitive inhibition lowers Vmax), which is why those scenarios don’t fit competitive inhibition.

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