Why does a pH of 5 produce high ATP synthase activity, but a pH of 3 and 9 very low ATP synthase activity?

ATP synthase works best at a pH of 5, but changes in the pH of the medium can alter its enzymatic activity, decreasing it.

Explanation:

Enzymes are specialized proteins that contribute to biochemical reactions occurring faster, decreasing the activation energy.

Under ideal conditions of temperature and pH, enzymes can work at their maximum capacity, but changes in these conditions can affect the speed with which an enzyme acts.

ATP synthase, an important enzyme for ATP synthesis and oxidative phosphorylation, works best at a pH of 5 (weak acid), but as the acidity or alkalinity of the medium increases, enzymatic activity decreases.