enzyme inhibitors

• •Non competitive inhibitors bond the allosteric site of the enzyme and change its tertiary structure. This changes the shape of the active site so the substrate won’t bond to it and the enzyme can’t catalyse the reaction

  
• •Competitive inhibitors bind to the active site of enzymes, this blocks the substrate from binding to the active site so the enzyme can’t catalyse the reaction

  
• • The competitive inhibitor is competing for the active site against the substrate.

  • Increasing the concentration of an inhibitor reduces the rate of reaction.

  • If inhibitor concentration continues to be increased, the reaction will stop completely.

  • If we increase the substrate concentration we can increase the rate of reaction again to overcome this.

  
• • Non-competitive inhibitors are attaching to an alternative site so are not competing with the substrate.

  • This changes the shape of the active site so the substrate cannot bind and rate of reaction will decrease.

  • Increasing the substrate concentration cannot increase the rate of reaction as the shape of the active site of the enzyme remains changed and enzyme-substrate complexes are unable to form

  
• •Competitive inhibitors reduce the rate of reaction for a given concentration of a substrate. However they do not change the Vmax of the enzyme they inhibit.

  •If the concentration of the substrate is increased yet further, the original Vmax can be met as there is so much more substrate than inhibitor.

  •The effect of non-competitive inhibitors cannot be overcome by increasing substrate concentration. However, we can reduce availability of active sites further by decreasing rate of reaction through increased concentration of the inhibitor.
• Reversible inhibitor - When an inhibitor binding can be reversed
• Irreversible inhibitor - When an inhibitor bind permanently to an enzyme
• End product inhibition - When the product of the reaction acts as an inhibitor of the enzyme that produces it
• Some medical drugs are inhibitors

  Statins:

  • Inhibit enzymes used to produce cholesterol

  • These are used to reduce the risk of heart disease

  Aspirin:

  •Irreversibly inhibits COX  preventing the production of chemicals that cause pain and fever