What Are the Effects of pH on Amylase?

The main effect of pH on amylase is “denaturization,” which means that the enzyme changes its shape and basically stops working, or at least stops working efficiently. Amylase is an enzyme that exists in human saliva, in the pancreas of humans most animals, and in the cells of a number of plants and bacteria. It helps in the digestion and breakdown of food, but if the environment is too acidic or too basic, things often start to deteriorate. Readjusting the pH levels will often reverse this, but not always.

Chemists and scientists use pH as a standardized measure of the acidity of various liquid solutions. The pH scale is a universal tool that helps people understand whether a solution is acidic or basic, and these characteristics are generally displayed numerically on a scale from 1 to 13. Substances exist at the ends of this scale are usually either highly corrosive or caustic. Hydrochloric acid, for instance, has a pH of 1, and lye usually hits close to 13. Most organisms have a certain pH range in which they do the best, and amylase is no different. When things go either lower or higher, the enzyme often can’t keep up with the changed environment and starts to break down.

There are three primary types of the enzyme and each has a slightly different optimum pH. Alpha-amylase, also known as “pancreatic amylase” thanks to its high concentrations in the pancreas, thrives with a pH between 6.7 and 7.0, whereas the beta form of the enzyme, commonly found in saliva, does best between 4.6 to 5.2. Gamma-amylase is most commonly found in plants and bacteria, and it is best suited for conditions with a pH close to 3.

Under ideal conditions, the main job of the amylase enzyme is to convert starches to glucose sugars that can be more easily digested and, in humans and most animals, absorbed into the bloodstream. This is why starchy foods like potatoes and rice often taste sweet when chewed, since amylase actively converts some of the food’s starch molecules to sugar while the food is in the mouth. It does this by breaking glycosidic bonds and altering their basic chemistry using ionic charges. Scientifically the enzymes are known as “catalysts” for this reason, since they typically either start or speed up chemical reactions.

Changes in pH can denature the enzyme by changing the protein's ionic charge. Ionic bonds create the functional shape of the enzyme. When the ion charge changes, though, the shape of the enzyme changes, which in turn changes its function. The enzyme will typically keep trying to break down starch molecules, but it won’t usually be able to, at least not fully. This can cause a number of problems for the plant or animal trying to get food energy since the starches may not be efficiently processed or prepared for digestion.

pH levels in the environment and the body can change for a number of different reasons. In people the main causes tend to be illness and disease, though temporary or brief changes can happen as a result of shallow or strained breathing, which can alter the oxygen level of the blood; excessive consumption of highly acidic foods and beverages, particularly alcohol; and certain pharmaceutical drugs. Plants and bacteria are often impacted by the conditions of the environment, including water and soil. Pollution can be very troublesome in this regard.

In addition to the effects of pH on amylase, other factors that affect enzymes are heat and heavy metal ions. Most enzymes that are found in the human body work best at a normal body temperature of 98.6°F (37°C). Heavy metal ions, such as those from lead, silver, copper and mercury, are called enzyme inhibitors. They denature protein molecules in enzymes, inhibiting or preventing the enzyme from working properly by changing the shape of the enzyme and the active site of the molecule so much that it can no longer can cause a chemical reaction.