Wht Is the Relationship between Enzymes and pH?

Valerie Clark

The relationship between enzymes and potenz hydrogen (pH) is tied to enzyme function. Enzyme stability is greatest under certain environmental conditions, with pH being the primary contributing factor. Maximum enzyme activity and stability are reached at the optimum pH level. If the environment pH is above or below the optimum pH level, the enzyme will become inactive or less active.

Amylase is an enzyme found naturally in the digestive tract.
Amylase is an enzyme found naturally in the digestive tract.

The effect concerning enzymes and pH occurs at the molecular level and can alter enzyme structure and stability because enzymes are largely built from amino acids that have acidic or basic characteristics. Enzymes are highly specific by nature. An enzyme becomes activated when the appropriate substrate bonds to the enzyme like a lock and key. A chemical reaction occurs when an enzyme is activated and the enzyme acts as a catalyst for the reaction. If the pH of the environment is extremely out of range, an enzyme can denature and lose function altogether.

The best enzyme activity and stability are reached at the optimum pH level.
The best enzyme activity and stability are reached at the optimum pH level.

To illustrate the relationship between enzymes and pH, consider the case of amylase, an enzyme that aids in digestion. The optimum pH for amylase is achieved in the stomach, which is where the enzyme begins to break down carbohydrates. The pH of saliva inside the mouth is higher than the optimum pH, so amylase is not activated while chewing. The same holds true for the small intestine — the pH is similar to saliva. The main factor is pH because it has a direct effect on when the enzyme becomes active and inactive throughout the digestive system.

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Several other digestive enzymes are tightly regulated by pH. Trypsin and pepsin are involved in breaking down food for digestion. Although trypsin is activated at a neutral to slightly acidic pH, pepsin remains inactive until it reaches the stomach.

The pH also has a major effect on ionic binding, which is essential for enzyme activation and chemical reactions. In an environment where enzymes and pH become unstable, the enzyme structure can change as a result of an increase or decrease in pH. A change in enzyme structure will likely have an effect on ionic binding, which is necessary to drive chemical reactions. The rate of the reaction can change or stop entirely. In a biological system, an unexpected change in pH can have a major effect downstream.

Enzymes and pH are also connected in terms of stability. When an environment reaches the optimum pH level for an enzyme, a point of optimum stability is also achieved. When an enzyme is optimally stable, it is able to remain activated, which drives chemical reactions.

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Discussion Comments


@turquoise-- The nature of those enzymes will be changed. Wrong pH balance basically changes the structure of the enzyme preventing it from attaching to the active site it's meant for.

Enzymes have some capacity to adjust to changes that occur with the shape of the active site. But if their structure is changed due to pH or temperature, they can't attach.


@turkay1-- Actually, most enzymes are activated at a neutral pH, so neither alkaline nor acidic. Of course, there are exceptions to this such as the enzymes in the stomach that are activated at an acidic pH.

But think of it this way, enzymes are made to be activated at different pH levels for a specific reason. The body doesn't want these enzymes to be activated just anywhere. It needs to be activated in the right place. So the difference in pH levels and its affects on different enzymes is actually what makes the system work.

Of course if there are underlying conditions that affect pH levels in different parts of the body, it will be problematic for enzyme function leading to certain health issues. But for the most part, our body knows what to do and how to do it when it comes to enzyme activity and pH.


As far as I know, the overall pH in the body needs to be alkaline. If it becomes acidic preventing the activation of certain enzymes, what will happen? Will this result in disease or dysfunction of the system?

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