Inhibitors (Competitive and Non-Competitive)

Key Questions

  • Answer:

    to let another molecule not being processed


    Enzyme is the digestive system to break down the big molecules to small so it can be used by the cell...Enzyme inhibitors are so important especially in medicine to prevent the molecules to be processed and create bad clinical manifestation for example like allergy

  • Answer:

    competitive inhibitors compete with the actual ligand for the binding site in protein whereas non-competitive inhibitors do not.


    is a substance that reduces or decreases the activity of an enzyme. It inhibits the proper functioning of enzyme.

    Competitive inhibitors
    competitive inhibitors are those which mimics the shape of the actual substrate and binds to the active site.

    Figure below explains the functioning, substrate comes and binds to enzyme undergoes product formation and releases the site, making it available for new substrate to come and bind.

    when a competitive inhibitor is present which mimics the substrate and binds with the enzyme but is not converted to any product and competes for the enzyme active site with actual substrate.
    in simple terms enzymes activity decrease in presence of Competitive inhibitor

    in the figure below the enzyme kinetics is low at low concentration of substrate but as the substrate amount increases its activity also reaches back to its normal

    Non-competitive inhibitors
    Non-competitive inhibitors do not compete for the active site with substrate but does not allow substrate to bind at the active site.

    These are actually of two types
    1. Allosteric as shown in first figure BELOW, they bind at different position but actually causes change in the active site so new substrate moity cannot bind.
    2. in the second figure BELOW the substrate is sterically hindered, blocking the active site so as substrate can not interact with the enzyme.
    Figure 1
    Figure 2 (sorry couldn't find any better resolution)

    in simple terms Non-Competitive Inhibitors do not allow the substrate to bind at the active site.

    in the figure below the enzyme activity is low at low concentration of substrate but as the substrate amount increases its activity cannot reach the normal level unlike the competitive inhibitor.

  • Answer:

    Inhibit the enzymes function thus becomes inactive or reduces its efficiency.


    Competitive inhibitors are molecules which are very similar to the enzymes natural substrate, and thus compete for the active site. As a result, the the inhibitor binds to the active site and remains their, preventing further reactions.

    The enzyme may react with the inhibitor and release the products as it would usually do to its substrate, thus the inhibitor and substrate compete for the active site.

    Non-Competitive inhibitors bind to an allosteric site of the enzyme (A site on the enzyme which is not the active one). This results in a conformational change of the protein, distorting the active site and thus is unable to bind the substrate. So long as the non-competitive inhibitor is bound, the enzyme remains inactive.