How does salt concentration affect enzyme activity?

In this brief guide, we are going to answer the question “how does salt concentration affect the enzyme activity” with an in-depth analysis of the effects of salt concentration on the enzyme activity. Moreover, we are going to highlight what enzymes are and how they are affected by different factors.

How does salt concentration affect enzyme activity?

The salt concentration increases the enzyme activity to a certain level but too much salt can decrease the enzyme reaction rate or activity by denaturing the enzymes. The nature of the salt is also important as monovalent ions can not affect the activity to too much extent whereas divalent ions, especially metal ions, may inhibit the activity of enzymes by blocking the enzymes.

Effects of salt concentration on enzyme activity:

  1. Salt concentration:

Like another pH, temperate, enzyme, and substrate concentrations, the activity of the enzymes can also be altered by salt concentration. In general, the increase in the concentration of salt to a certain level increases the activity of the enzymes as enzymes are proteins and when the salt is increased, it increases the number of ions in the solution.

These ions can change the electrostatic forces between the amino acids responsible for the tertiary structure of the enzymes. This alteration in the protein structure makes the enzyme malfunction or denature.

The effect of salt concentration on the activity of enzymes may vary from one enzyme to another as some enzymes need salt in small amounts for their activities. In this case, if the concentration is very low or even is at zero, the amino acid chains forming the enzymes will attract each other, become precipitated, and denatured.

On the other hand, if the concentration is too high, the normal electrostatic attractions among the molecules of enzymes may be blocked and the enzyme will become denatured. For instance, different enzymes in blood maintain their activities at an optimum level when the salt concentration of the blood is maintained at 0.9%.

  1. Nature of salt:

Not only the concentration but also the nature of the salt also affects the enzyme activity by affecting the ionic strength of the solution. For instance, if sodium chloride is increased, several enzymes may stop their activity due to the inhibitory effects caused by chloride ions or some other metal ions. Another example is the slowing down of the browning in apples through the addition of table salt.

The high concentration of salts may affect the activity of enzymes in that the salt may affect the water activity of the solution which in turn alters the enzymatic activity of the solution. The salts with monovalent ions may neutralize the charges of the protein equally when increased in the solution and have the potential to change the protein structure with or without causing any effect on the enzymatic activity.

Salts with divalent cations may form the salt bridges of the acidic amino acids and can affect the activity. But the salts with heavy metals are generally inhibitors of the enzymatic activity.


Some experiments conducted proved the effects of salts on the activity of enzymes. The salts can affect the activity of polyphenol oxidase found in food products and cause browning.

Moreover, the effect of salt concentration on an isozyme, malate dehydrogenase, is studied and it was found that no matter what is the pH, the enzyme activity is increased with the increase in the concentration of NaCl up to 0.02 M. Any further increase is found to be inhibitory for enzymatic activity.


Enzymes are the proteins that lower the activation energy of the reaction and increase the rates of chemical reactions without altering their structures. Enzymes act as catalysts.


Enzymes regulate the chemical reactions that occur in most of the biological processes with living organisms. The cell metabolism is also catalyzed by enzymes, including digestion of the food, in which proteins, fats, and carbohydrates are broken down into smaller pieces.

Some of the diseases, such as albinism and phenylketonuria, also result from the deficiency of some particular enzymes in the body. The enzymes also find their activities in medical and industrial applications. They are responsible for the fermentation of wine, curdling of cheese, and brewing of beer through catalyzing the chemical reactions involved in the preparation of these food products.

In the medicinal field, enzymes are used to kill the disease-causing microorganisms, promote the healing of wounds, and diagnose some specific diseases.

Effects on enzymatic activity:

The activity of enzymes can be affected by different factors, including pH, temperature, substrate concentration, and enzyme concentration itself.  An optimum pH and temperature are required for the proper activity of enzymes and the activity can be increased with the increase in PH and temperature to a certain level after which the process is affected adversely through denaturing the enzyme.

An increase in enzyme and substrate concentration also increases the rate of reactions to a certain level and after all the enzymes become saturated, any further increase will not increase the rate of reaction.

Other FAQs about Salt that you may be interested in.

Can you drink boiled salt water?

Why does salt melt slugs? 

How to counteract too much salt in food?


In this brief guide, we answered the question “how does salt concentration affect enzyme activity” with an in-depth analysis of the effects of salt concentration on the activity of enzymes. Moreover, we discussed what enzymes are, what are their functions, and how different factors can affect enzymatic activity.

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