Enzymes are biological catalyst which increases the rate of chemical reactions inside the body without being chemically changed itself.

Enzymes are produced by the cytoplasm of a cell.

Enzymes, as every one knows, breaks down complex substances such as starch and turns it  into a simpler, smaller substance.

The specialty of an enzyme is that an enzyme never dies after completing its purpose.It is rather sent to catalyze or synthesize other chemical reactions.

Fact: Did you know that one catalase can catalyze(break down) 5,000,000 molecules of hydrogen peroxide in one second!


The breakdown of food to smaller substances, small enough to diffuse through the plasma membrane of a cell, is called digestion. Interesting to know that the enzymes are only produced when there is food enters our body.

Types of enzyme reactions:

  • There are enzymes found in the body that do not break down complex substance but rather they synthesize (build) complex substances from simpler substances.
  • The enzymes involved in specific chemical reactions, such as oxidation of glucose, work in groups along other enzymes which are produced for the same purpose.
  • Some chemical reactions discharge hydrogen peroxide. The cells produce the catalase which breaks down hydrogen peroxide to water and oxygen.

   Types of Enzymes:

  • Carbohydrases are enzymes meant to break down carbohydrate only.
  • Proteases break down protein.
  • Amylase breaks down starch.
  • Lipases breaks down fat.
  • Cellulase breaks down cellulose.

Enzymes are specific and only catalyze the substances it is made to catalyze.

How it works?

How enzyme works can be understood by the lock and key hypothesis.450px-Induced_fit_diagram.svg

Every enzyme has an active site. An enzyme is like a lock in which the substrate binds like a key. The catalyzed molecule or to be catalyzed molecule  is called a substrate. Now when the molecule is placed in the active site the Enzyme would tighten its grip and won’t let it go until it is either broken down or built up according to the enzyme’s nature.

Enzymes Denatured

Enzyme is most affected by the pH and temperature. Sudden increase in temperature and change in pH value denatures an enzyme.


Every enzyme has a particular optimum temperature. The optimum temperature is the one in which it works best. This is because every particle and cell gains a lot of kinetic energy by high temperature, meaning the enzymes collide with the substrate and binds with them even faster than normal. The enzymes, unlike any other particle or cell, denatures only when the temperature is high. This is because the enzymes are proteins and proteins are broken down by intense heat.

You can take the example of an egg. The egg white is all protein. When the egg is placed in a boiling water the proteins start to break forming a solid protein. When you crack open a boiled egg you will notice the protein as the white part of the boiled egg.

The enzymes would also start to crumble in high temperature and would soon loose the shape of its active site. This results in, the enzyme becoming useless, this is denaturation.

However, the enzymes do not denature in low temperature. This is because every particle or cell gains high kinetic energy in high temperature but when the temperature is low then the molecules loose their kinetic energy but do not loose their shape nor are they broken down. This results in a lower enzyme activity but in the end the product remains the same.

Some enzymes work in higher temperature. For example in volcanic areas, bacteria exists in intense temperature. They produce enzymes as well which work in such intense conditions.

pH value:

Enzymes are adversely effected by the pH values. Mostly the enzymes work best at the pH value of 7 which is neutral. Any increase or decrease in the value results in the enzyme being denatured. This is because the enzymes react adversely towards hydrogen ions. The pH value calculates the increase or decrease in the hydrogen ions which makes a chemical acidic or alkaline. The enzymes work best at optimum pH value because in this value a chemical has the perfect number of hydrogen ions. High or low amount of hydrogen ions affect the protein of an enzyme and destroy its shape permanently. However some enzymes work in extremely low pH or even in high pH value.

For example, in the stomach when the gastric juice is produced, the pH value decrease to 2, but the stomach still produces enzymes called pepsin which work in this condition.

However, the pH value does not remain constant in a chemical reaction involving enzymes. To keep the pH value constant, scientists use specific solutions called Buffer Solutions which help control the pH value during the chemical reaction. Buffer solutions have salts in it which resist the change in pH values.

Hydrogen peroxide

After the metabolism reactions occur, waste products are formed, these are hydrogen peroxide. This is harmful to the cells of an organism. The liver produces enzymes which catalyze the hydrogen peroxide and produces water and oxygen both of which are used for tissue respiration.

Effects of substrate and enzyme concentration:

The rate of chemical reaction is affected by the concentration of substrates and enzymes. A higher number of substrate than the enzymes limits the increase in rate of chemical reactions as enzymes would be busy catalyzing or synthesizing other molecules.

A higher number of enzymes than the substrate would also provide with same result after a while because the low amount of substrate means they are already occupied while all the other extra enzymes have nothing to do!

Limiting factor:

The limiting factor is simple. The factor that limits the increase in rate of chemical reaction is called the limiting factor. For example, the high number of substrate was the limiting factor.


As the name says these enzymes are helpers of enzymes. The coenzymes are not made of protein however. Some enzymes require the co enzyme to merge with it before catalyzing a molecule.

With this I conclude this article.

Thank You for reading!



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