Effect of pH on enzyme activity

The H⁺ ion is the general effector of enzymatic reactions. The concentration of H⁺ determines the pH of the medium, which affects both the kinetic parameters of enzymes and the conformational parameters of proteins, as they are highly sensitive to pH variations.

Measuring many enzymatic activities as a function of pH results in curves that pass through a maximum, indicating the existence of an optimum pH. Consequently, the optimal pH has been determined for many enzymes.