Catalase works only at the pH level of 4, and any other pH level denatures the enzyme.
Primarily by the concentration of the Hydrogen ion H+.
The Ph of enzymes depend on where they are in the body. In the intestine and stomach you would be looking at the Ph of an enzyme there to be 1 or 2, very acidic, because it need to break down...
The activation energy of a reaction is lowered by enzyme.
If you change the pH, the enzyme can become inactive and won't be able anymore to forfill its function.
The optimum pH for enzyme amylase is 4.8. however, salivary amylase has an optimum pH of 6.7
The Difference Between Digestive and Systemic Enzymes
How to Determine the Best Enzyme Supplement
How to Find the Best Enzyme for You
The Guidelines for Systemic Enzymes