Effects on Enzyme Activity Changes in the pH or acidity of the environment can take place that would alter or totally inhibit the enzyme from catalyzing a reaction. This change in the pH will affect the polar and non-polar intramolecular attractive and repulsive forces and alter the shape of the enzyme and the active site as well to the point where the substrate molecule could no longer fit, and the chemical change would be inhibited from taking place as efficiently or not at all. In an acid solution any basic groups such as the Nitrogen groups in the protein would be protonated. If the environment was too basic the acid groups would be deprotonated. This would alter the electrical attractions between polar groups.
Every enzyme has an optimum pH range outside of which the enzyme is inhibited.
Still other enzymes like the lipases will function most effectively at basic pH values. If the pH drops in the blood called acidosis then enzymes in the blood will be inhibited outside their optimal pH range. If the pH climbs to an unacceptably high value called alkalosis then enzymes cease to function effectively. Normally, these conditions do not take place because of the highly efficient buffers found in the blood that restrict the pH of the blood to a very narrow range. Buffers are a substance or mixtures of substances that resist any change in the pH. There are many buffer systems found in the body to adjust the pH so that enzymes might continue to catalyze their reactions.