How pH affects enzymes
Enzymes are also sensitive to changes in pH. The protein chain the enzyme molecule is made from is coiled and folded into a very specific shape. This shape is held together by the attraction between positive & negative charges on different parts of the molecule. The pH of the surrounding environment can affect the charges on the enzyme molecule, causing them to be changed. This can cause the protein chain to unfold or uncoil. Even a slight change in an enzyme molecule's shape can prevent it from working properly. This change of shape is called denaturing.
Most enzymes work best at a pH around neutral. Changing the pH by just one unit either way will usually prevent and enzyme from working. Amylase works best at a pH of around 7.5, so placing it in a solution greater than pH8.5 or lower than pH6.5 will prevent it from working at all. Some enzymes work at extreme pH levels. Pepsin, an enzyme found in gastric juice in the stomach, works best at pH 2.
