Enzyme inhibitors

• Enzyme inhibitors reduce the rate of the reaction. There are two types of inhibitors, competitive Inhibitors non-Competitive Inhibitors. 
• • Competitive inhibitors have a similar shape to the substrate molecule and must have a complementary shape to the active site of the enzyme.
  • They enter the active site and bind with it forming an enzyme-inhibitor complex. This prevents the normal substrate from entering by blocking the active site.
  • The number of enzyme-substrate complexes that can form are therefore reduced and the rate of reaction falls.  
• Competitive inhibitors:

   

  If the concentration of substrate is increased then the level of inhibition will decrease since this will increase the chance of the normal substrate binding with the active site.  
• • Non-competitive inhibitors do not compete with substrate molecules for the active site. Instead they attach away from the active site (at the allosteric site) and distort the tertiary shape of the enzyme which leads to a change in the active site shape.
  • This means the substrate no longer fits the active site, so Enzyme Substrate Complexes cannot form and the rate of reaction will decrease.
  • The inhibitor may be a completely different shape to the substrate. 
• Non- competitive inhibitors:

  Increasing the substrate concentration will not increase the rate of reaction. 
• Competitive and non-competitive inhibitors can either be reversible or non-reversible inhibitors.  
• Inhibitors that do not permanently bind with active sites or away from the active site are described as reversible inhibitors.
• Inhibitors that permanently bind to the active site or away from the active site and are non-reversible.