The activity of an enzyme can be modulated, or regulated, by changing the pH. This means that the pH level of the environment in which the enzyme is present can affect how the enzyme functions. Enzymes are proteins that act as catalysts in biological reactions, and their activity is usually optimal at a specific pH range. Any deviation from this optimal pH can cause the enzyme to become less active or completely inactive. pH can affect an enzyme by altering its 3D structure, which is important for its function. Changes in pH can disrupt the hydrogen bonds and ionic interactions that stabilize the enzyme`s structure, leading to a loss of activity. Therefore, pH is an important factor that can modulate the activity of an enzyme.