Perhaps you are unaware but your digestive system is like one big chemical lab. There are hundreds of reactions that occur in your body to absorb the nutrients from your food. And the catalyst for all these reactions is enzyme. They have several other functions in your body too. Let us learn all about them.

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Enzymes can be simply described as biological catalysts. Like any catalyst enables a chemical reaction, they do the same for your body. In most reaction energy has to be provided, usually in form of heat. Enzymes actually reduce the activation energy needed and increase the velocity of biological reactions in the human body. But in this process/reaction, they do not undergo any changes themselves. Hence this is the reason they are recyclable and the required in very small doses.

Structure of an Enzyme

Enzyme is a form of protein. As far as the structure goes they are globular, that is they are cylindrical in shape. Their polypeptide chains have a coil-like formation.

The sequencing of the amino acids decides not only define the structure of an enzyme but also its functions. The distinctive structure of an enzyme will determine its catalytic activity. In a particular configuration (or sequencing) a particular portion of the structure, known as the active site is accessible to attract and catalyze the reactants.

You can download Biomolecules Cheat Sheet PDF by clicking on Download Button Below

biomolecules cheat sheet

Biomolecule cheat sheet

Functions of an Enzyme


Now enzymes are highly specific in their functions. A particular enzyme will only act as a catalyst for a particular reaction. In a given specific reaction the molecules that an enzyme reacts with is a substrate.

The substrate binds itself to the active site of the enzyme. This is the lock and key theory. So only the correct enzyme can react with the correct substrate, just like only the perfect key can unlock a particular lock. Although in modern times we believe that the substrate alters its binding to fit with the active site, This is known as induced fit.

After the catalyses of the substrate, we are left with what we call the products. It is important to note that throughout this entire process the molecular structure of the enzymes does not undergo permanent alteration. It keeps its structure enact and performs its functions again.

Just like proteins, enzymes can also be denatured. This happens when their structure changes due to some external force or pressure. Generally, heat causes them to denature and lose their catalyzing abilities.

Classification of Enzymes

The classification of an enzyme is on the basis of the reaction they catalyze.  The classification is as follows

  • Oxidoreductases: Catalyze oxidation-reduction reactions
  • Transferases: These obviously catalyze reactions of group transfer
  • Hydrolases: Hydrolysis reactions are catalyzed by them
  • Lyases: one of the lesser known enzymes
  • Isomerases: These change the shape of the molecule after catalysing its structural shifts
  • Ligases: And these catalyze ligation processes

Solved Example for You

Q: An Enzyme will mainly consist of which of the following?

  1. Globular proteins
  2. Fibrous proteins
  3. Nucleic Acids
  4. Fats

Sol: The correct answer is “A”. Enzymes mainly consist of globular proteins. During enzyme formation, hundreds of amino acids string together to form a globular protein molecule.

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