pH plays a very important role in how enzymes work because it affects the shape and charge of the enzyme and its active site.
1. Each enzyme has an optimum pH:
- Every enzyme works best at a specific pH, called its optimum pH.
- At this pH, the enzyme’s structure and active site are in the best condition for binding to the substrate.
Examples:
- Pepsin (in the stomach) works best at pH 2 (acidic).
- Amylase (in the mouth) works best at pH 7 (neutral).
- Trypsin (in the intestine) works best at pH 8 (slightly basic).
2. Effect of pH changes:
- If the pH becomes too acidic or too basic, it changes the charges on the enzyme and substrate.
- This can change the enzyme’s shape, especially the active site.
- When the shape changes, the substrate no longer fits, and the enzyme loses its activity.
- Extreme pH changes can cause denaturation (permanent damage to the enzyme).
In short:
- Enzymes work best at a certain pH (optimum pH).
- Too high or too low pH changes their shape and stops them from working properly.