What is the effect of pH on enzymes?

Enzymes have an optimum pH where activity is at its maximum and when the pH is made more acidic or alkaline the activity drops to zero, and under these conditions the active site denatures Each enzyme has a specific optimum pH, an example of this would be a protease enzyme in the stomach which functions best at an acidic pH, or an enzyme which is released from the pancreas into the small intensive, such as lipase, functions best at an alkaline pH