Inhibition in enzymes | Types, Examples

what is enzyme inhibition?

Enzyme inhibition is the procedure of reducing  or stoping  the activity of an enzyme. Enzymes are amino acids that catalyze chemical reactions in living  creature, and their activity can be controlled  through various process, including inhibition.

Enzyme inhibitors are molecules that attach to an enzyme and disturb its activity by altering

  • the enzyme’s shape
  • blocking the active site where the substrate binds
  • or altering the enzyme’s ability to bind to the substrate.

Examples of enzyme inhibition

Examples of enzyme-inhibiting agents are cimetidine, erythromycin, ciprofloxacin, and isoniazid.

Importance of enzyme inhibition:

Enzyme inhibition playing an important role in controlling cellular functions and is applicable in the development of

  • Drugs
  • And other therapeutics.

Types of enzyme inhibition

Enzyme inhibition contain three main types:

  1. uncompetitive inhibition.
  2. competitive inhibition,
  3. non-competitive inhibition

1. Uncompetitive inhibition:

Uncompetitive inhibitors bind to the enzyme-substrate complex, preventing the complex from completing the reaction. Uncompetitive inhibitors

  • have a higher affinity for the enzyme-substrate complex than for the enzyme or substrate alone.
  • Increasing the concentration of substrate cannot overcome the inhibition by uncompetitive inhibitors.

A part from these three main types of inhibition, there are several  other types of inhibition, such as

  • mixed inhibition
  • and suicide inhibition.

which contain more complex interactions among the enzyme and inhibitor.

Understanding the type of inhibition is important for

  • predicting and controlling the effects of enzyme inhibitors,
  • and for the development of effective therapeutic strategies.

2. Competitive inhibition:

Competitive inhibitors are molecules that attach at the active site of an enzyme, reduces the chances of substrate binding. They compete with the substrate to get contact with the active site. Competitive inhibitors commonly looks like the substrate and attach to the active site with a similar attractions. As a result,

  • increasing the concentration of substrate can oppressed the inhibition.

3. Non-competitive inhibition:

Non-competitive inhibitors attach to a different site on the enzyme, known as an allosteric site, triggering a conformational change that deceasing the enzyme’s activity. Non-competitive inhibitors not get competition with the substrate for binding to the enzyme, and increasing the concentration of substrate cannot oppressed the inhibition.

Factors necessary for enzyme inhibition

factors necessary for enzyme inhibition are given below

Presence of an enzyme:

Enzyme inhibition wants the existence of an enzyme, which is a protein that catalyzes a specific chemical reaction.

Presence of an inhibitor:

Enzyme inhibition requires the existence of an inhibitor, which is a molecule that attach with  the enzyme and as a result decrease its activity.


Enzyme inhibitors should  be specific to the enzyme they are targeting. This means that they should not attach or interact with other enzymes or proteins in the  living organism.

Binding affinity:

The inhibitor necessarily have a high binding tendency for the enzyme in order to successfully inhibit its activity.


The concentration of the inhibitor and the enzyme should be proper  for the acquired level of inhibition.


The inhibitor must have enough time to attach  with the enzyme and form the desired level of inhibition.

Factor effecting enzyme inhibition

The factors that can affect enzyme inhibition are given below:

Concentration of inhibitor:

The concentration of the inhibitor can directly affect the level of enzyme inhibition. A lower

concentration of inhibitor generally results in lower inhibition of enzyme activity.

Concentration of enzyme:

The concentration of the enzyme can also regulate the level of enzyme inhibition. A higher concentration of enzyme may demand a higher concentration of inhibitor to gained the same level of inhibition.


Understanding above given factors is necessary for expecting and regulating  the effects of enzyme inhibitors, as well as for the growth of effective therapeutic strategies.

Important Questions about Enzymes

  1. Enzymes MCQs
  2. Inhibition in enzymes
  3. Which enzyme digests starch?
  4. Which enzyme digests protein?
  5. which enzyme is present in saliva?
  6. Which enzyme is not present in succus entericus?
  7. Which enzyme breaks down protein in the stomach?
  8. Which enzyme converts fibrinogen to fibrin?
  9. Which enzyme converts glucose into alcohol?
  10. Which enzyme digests fat?
  11. Which enzyme digests milk protein?
  12. Which enzyme is used in PCR?
  13. Which enzyme unzips the DNA double helix?
  14. Which liver enzyme increases with alcohol?
  15. Which enzyme cuts DNA?
  16. Which enzyme catalyzes the first step of glycolysis?
  17. Which enzyme binds DNA fragments together?
  18. Which enzyme transcribes DNA into RNA?
  19. which enzyme adds new nucleotides?
  20. Which enzyme digests cellulose?
  21. Which enzyme separates the two strands of DNA?
  22. Which enzyme converts carbohydrates into glucose?
  23. Which enzyme removes RNA primer?
  24. Which enzymes help in digestion?
  25. Which enzyme works best in acidic conditions?
  26. Which enzyme synthesizes tRNA?
  27. Which enzyme secreted by pancreas?
  28. Which enzyme converts maltose into glucose?
  29. Which vitamins work as coenzyme?