Enzyme inhibitors

• • An enzyme's activity can be reduced or stopped, temporarily, by a reversible inhibitor
  • There are two types of reversible inhibitors:
  • Competitive inhibitors have a similar shape to that of the substrate molecules and therefore compete with the substrate for the active site
  • Non-competitive inhibitors bind to the enzyme at an alternative site, which alters the shape of the active site and therefore prevents the substrate from binding to it
• Inhibition

  
• Reversible inhibitors


  Can act as regulators in metabolic pathways
• Metabolic reactions must be very tightly controlled and balanced, so that no single enzyme can 'run wild' and continuously and uncontrollably generate more and more of a particular product
• Metabolic reactions controlled by end-product inhibition


  1. Enzyme converts substrate to product

  2. End-product binds to alternative site on enzyme, changing active site shape and preventing further enzyme-substrate complexes

  3. End-product detaches, allowing active site to reform and enzyme to return to active state

  4. As product levels fall, enzyme begins catalysing reaction again in continuous feedback loop
• End-product inhibition

  Process where the end-product of a particular sequence of metabolic reactions acts as a non-competitive, reversible inhibitor