Why does a change in pH usually produce a change in the ability of an enzyme to act as a catalyst?
A. When the pH changes, the enzyme may lose its native conformation and lose its ability to function as a catalyst.
B. When the pH changes, enzymes are surrounded by a solvation shell that prevents them from interacting with substrates.
C. When the pH changes, the substrates are protonated and no longer bind to the binding site.
D. When the pH changes, the binding sites of enzymes interact with additional protons causing a localized positive charge that repels the substrate.