How enzyme works? Write the nature of enzymes | Describe structure of enzymes.

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How enzyme works?

  • When an enzyme combines with a substrate, it forms an enzyme-substrate complex.
  • The enzyme react with substrate to form enzyme product complex i.e. product is form which soon leave the enzyme.
  • The enzyme itself remains unchanged, thus can be used again for another substrate.






Write the nature of enzymes.

  •  Most enzymes are three dimensional proteins in nature, although a few are catalytic R molecules called ribozymes.
  • The ribozyme can catalyze specific substrate in a similar way as proteinaceous enzymes.

Example: Peptidyle transferase controls polypeptide elongation during translation process.


Describe structure of enzymes.

  1. Enzymes are generally globular proteins.
  2. The structure of enzyme depends on its active site.
  3. The sequence of amino acids specifies the structure of active site which determines catalytic activity of enzyme.
  4. An enzyme may have one or more active sites.
  5. Active site of enzyme consists of two parts i.e.


Binding site: Where substrate attaches.
Catalytie site: Where catalysis of substrate takes place.


The catalytic site is very small portion comprises of (2 to 12) amino acids.


Short Questions

Q1

Almost all enzymes are proteins, so which enzyme is not a protein?

Ribozyme.
Q2

Define enzymes.

Enzymes can be defined as biological polymers that catalyze biochemical reactions.
Q3

What is the induced fit theory?

The induced fit theory proposes that the active site of an enzyme is flexible. When a substrate binds to it, it causes a subtle change in the enzyme's shape. This conformational change allows the enzyme to fit more precisely around the substrate, which strengthens the bond and enhances the enzyme's ability to catalyze the reaction.
Q4

What are the examples of enzymes in plants?

Examples of plant-derived enzymes include amylase, protease and peroxidase.
Q5

Can an enzyme be called a polymer?

Yes, most enzymes are made up of proteins which are polymers of amino acids.
Q6

What are the types of enzymes present?

The types of enzymes are:

  • Oxidoreductases
  • Transferases
  • Hydrolases
  • Lyases
  • Ligases
  • Isomerases
Q7

What is an active site of an enzyme?

The enzyme’s active site is a cleft or a pocket within the enzyme where the substrate molecule binds and undergoes chemical reactions to be converted into the product.






  1. Define an enzyme. Why are they called "biocatalysts"?

  2. What is the chemical nature of most enzymes?

  3. Who discovered the first enzyme, and what was it named?

  4. What is a substrate in enzymatic reactions?

  5. Name two key properties of enzymes.


  1. Explain how enzymes lower the activation energy of a reaction.

  2. Describe the "lock and key" model and the "induced fit" model of enzyme action. Which one is more widely accepted and why?

  3. Why are enzymes said to be "specific" in their action? Provide an example.

  4. Explain the terms "thermolabile" and "pH sensitive" in relation to enzymes. What happens to an enzyme at very high temperatures or extreme pH?

  5. What is the role of an active site in enzyme function?


  1. Describe the four levels of protein structure (primary, secondary, tertiary, quaternary) and explain how each level contributes to the overall function of an enzyme.

  2. What is an apoenzyme, a cofactor, and a holoenzyme?

  3. Give examples of different types of cofactors.

  4. How does the primary structure of an enzyme determine its higher-order structures and ultimately its function?


  1. Discuss the factors that affect enzyme activity (e.g., temperature, pH, substrate concentration, inhibitors).

  2. How is enzyme activity regulated in living cells?

  3. Explain the difference between competitive and non-competitive inhibition.

  4. Why is the study of enzymes important in medicine and industry?

  5. If a genetic mutation changes a single amino acid in an enzyme's primary structure, how might this affect its function?

  6. Design an experiment to investigate the effect of temperature on the activity of a specific enzyme (e.g., amylase).

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