Answer:
The correct answer is enzymes
Explanation:The activity of an enzyme varies with pH
For any enzyme, consider a curve representing the rate of the catalyzed reaction as a function of pH. The activity is initially relatively low and then increases to reach a maximum value; if the pH of the medium then continues to increase, the enzymatic activity decreases.
The optimum operating pH of the enzyme is that for which the enzymatic activity is maximal.
In the amylase example, the optimal pH is 7 (neutral pH).
The decrease in activity on both sides of the optimal value is interpreted by the change of ionization of the amino acids of the active site of the enzyme. When the amino acid side chain charges are modified, for pHs farther from the optimal value, the structure of the enzyme is modified, and by losing its form, the molecule loses its catalytic activity.
An optimal pH characteristic of each enzyme
Not all enzymes have an optimal pH of activity equal to 7, such as amylase.
Gastric pepsin has maximum activity in an acidic medium, for a pH close to 2. Pancreatic trypsin, which also plays a role in the digestion of proteins but is released in the intestine and not in the stomach, works it optimally in a basic medium, for a pH close to 8.