What is typically affected by both Km and Vmax?

The correct choice is related to the concept of enzyme kinetics, specifically how enzyme activity is influenced by various factors. In enzyme-catalyzed reactions, both Km (Michaelis constant) and Vmax (maximum velocity) can be affected by the presence of inhibitors.

When an inhibitor is introduced, it competes with the substrate for binding to the enzyme, which can change the Km value. For competitive inhibitors, Km increases, indicating that a higher concentration of substrate is required to achieve half of Vmax. Consequently, Vmax may remain unchanged for competitive inhibition but can decrease for non-competitive inhibition, affecting the maximum reaction rate regardless of substrate concentration.

This connection illustrates why inhibitor concentration is significant in understanding enzyme kinetics, as it can directly alter both the affinity of the enzyme for the substrate (indicated by Km) and the overall turnover rate at saturation (indicated by Vmax). This impact on both parameters is a fundamental aspect of elucidating how enzymes interact with substrates in the presence of regulatory molecules.

The other options do not directly relate to changes in both Km and Vmax in the same manner: enzyme concentration typically affects Vmax without changing Km; substrate type can alter how enzymes interact, but it primarily affects the dynamics of the reaction rather