How can a change in pH affect an enzyme activity?

A change in pH can significantly impact an enzyme's activity primarily by altering its shape, a phenomenon known as denaturation. Enzymes are proteins that have specific three-dimensional structures, which are crucial for their function. The active site of the enzyme, where the substrate binds, is shaped in a way that fits particular substrates. When the pH changes, the concentration of hydrogen ions in the solution also changes, which can affect the ionic bonds and hydrogen bonds that help maintain the enzyme's structure.

If the pH moves away from the enzyme's optimal range, it can lead to a conformational change, meaning the enzyme's shape can become distorted. This distortion can impair the enzyme's ability to bind to its substrate effectively, resulting in decreased activity or complete loss of function. Thus, an altered pH influences the very structure of the enzyme, making option A the most accurate statement regarding pH's effect on enzyme activity.