Enzymes are the marvellous organic catalysts produced inside living organisms, participating and controlling the essential chemical reactions of our life, without going any change during chemical reactions. Based on the number of bodily processes requiring enzymes, the human body is estimated to have over 20,000 enzymes. But all enzymes are yet to be identified.

What is Enzyme?

Enzymes are defined as the globular proteins that catalyse a biological chemical reaction. Enzymes are protein molecules made from a chain of amino acids. Enzymes are present inside each cell of plants and animals. They are produced inside our living cells, but they are not dependent upon the vital processes of the cell and work outside the cells. Some of the major known enzymes are lipase, protease, carbohydrase, isomerase etc.

Conditions for proper functioning

Enzymes play a great role in nutrition and other living processes. They act with maximum efficiency at a certain temperature (around the body temperature, 37.50 C) and pH level (different for different enzymes). A temperature lower or higher than 37.50 C slows down the functioning of enzymes.

At temperatures above 600 C enzymes starts getting permanently damaged. Similarly stomach enzymes like low pH level (2-2.5 pH level) but intestinal enzymes like around 7.5 pH level. As a matter of fact, enzymes act as a catalyst to let certain reactions happen, which can’t happen under normal conditions available inside the body.

Why enzymes?

Enzymes are much more efficient and better than artificial chemicals. Enzymes help in the performance of same reactions at much lower temperature and quicker timeframes, as artificial chemicals might require for the same. But enzymes are very specific in performance. One particular enzyme helps only in one particular type of reaction involving a substance or a group of closely related substances, known as “substrate”.

The specificity of any enzyme is a function of the substrate fitting the enzyme like a key fits its lock. The enzyme-substrate complex requires that group substrate and enzyme should be in correct relative position.


  • Intracellular Enzymes: Enzymes which are used in the cells which make them are called intracellular enzymes.
  • Extracellular Enzymes: Enzymes which are produced in cells which secrete them to other parts of the body are known as extracellular enzymes.


Coenzymes/activator, are organic molecules that are required by certain enzymes to carry out catalysts. Coenzymes are usually inorganic ions and increase the activity of a complete enzyme. Mainly coenzymes are related to vitamins. This is why vitamin deficiencies profoundly alter metabolism.

In the following articles, we will identify various types of enzymes and coenzymes with functions and how to keep them in supply.

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