How does does changing the pH affect the activity of an enzyme?

Enzymes are proteins which increase the rate of reactions by binding to substrates and forming enzyme-substrate (E-S) complexes. The part of the enzyme which binds to the substrate is called the active site. Enzymes require specific conditions to function, and when conditions vary too far from the optimum for that specific enzyme, it affects the shape of the active site and hence its activity.When pH changes, it can disrupt the hydrogen bonds which hold the active site in its tertiary structure (3D shape), and so the shape of the active site changes. This means that the substrate can no longer fit into the active site, and no enzyme-substrate complexes can be formed. When this happens, the enzyme is denatured, and the activity of the enzyme decreases.