What would you predict if you had first mixed the catalase (100%) in semi solutions of varying pHs of 3, 5, 7, 9, 11? What would you predict would be optimum pH?
I'll bet that you found the fastest rate at pH 7, with slower rates at higher and lower pH values.
Catalase is an enzyme. Its activity depends on the pH.
The most favorable pH value — the pH at which the enzyme is most active — is known as the optimum pH.
Extremely high or low pH values generally result in complete loss of enzyme activity.
The optimum pH value varies greatly from one enzyme to another.
For example, pepsin has its optimum at pH 1.5, while arginase has its optimum at pH 9.4.
I'll bet you found that the optimum pH for catalase was close to pH 7.