Final answer:
Each enzyme does indeed have its own optimum pH at which it functions most effectively. This is due to the enzyme's specific three-dimensional structure and the chemical properties of its active site. Deviations from the optimum pH can significantly affect enzyme activity and stability.
Step-by-step explanation:
The statement that each enzyme has its own optimum pH is true. Enzymes are highly specific proteins that catalyze biochemical reactions and are optimized to function at particular pH levels. Each enzyme works best within a narrow pH range, known as the optimum pH. This is the pH at which the enzyme exhibits its maximum activity and stability. For instance, pepsin, a digestive enzyme in the stomach, has an optimum pH of around 2, which is highly acidic, while trypsin, which operates in the small intestine, works best around a pH of 8, which is slightly alkaline.
Changes in pH can affect the enzyme's three-dimensional structure. A slight deviation from the optimum pH can reduce the enzyme's activity, while significant departures may cause permanent denaturation. The active site of an enzyme, where substrate molecules bind, has amino acid residues with their own acidic or basic properties that are optimal for catalysis.