Catalase is an enzyme, a protein that catalyses or accelerates chemical reactions. The human body uses catalase to break down hydrogen peroxide. While hydrogen peroxide is important for certain reactions in cells, it can also cause harm by damaging DNA. Catalase helps prevent damage by speeding the breakdown of hydrogen peroxide into oxygen and water.
Like other enzymes, catalase functions best at its optimal pH. At pH values other than the optimal pH, the activity of the enzyme will decrease. If the pH rises or falls too far the enzyme may become denatured and lose its structure; it will cease to have any activity at all.
The optimal pH for catalase in humans is 7 (neutral); the optimal value for catalases can vary in other species. At pH levels above 10, catalase is denatured, and at pH levels below 3.5, some catalases will dissociate into two subunits, although these effects again may vary for different species.
In order to exhibit a high level of activity, catalase must be in an environment where the pH is close to its optimal level. Cells prevent the denaturation of proteins and enzymes by controlling their pH through a variety of mechanisms. A buffer (a solution that resists change in pH) is the best way to achieve similar conditions in a laboratory experiment.