How enzymes work

• Enzymes


  Catalysts made by living organisms
• Enzymes


  • They are large proteins made up of long chains of amino acids
  • They can fold into different shapes, each shape being a unique enzyme that catalyzes a particular chemical reaction
• How enzymes work


  1. Enzyme has an active site with a unique shape complementary to the substrate

  2. Substrate binds to active site

  3. Enzyme catalyzes the reaction, speeding it up

  4. Enzyme is released unchanged after the reaction
• Substrate


  Reactant in a chemical reaction
• Products


  Smaller pieces that the substrate is broken into
• If the substrate doesn't fit the active site

  The reaction won't be catalyzed
• Lock and key model


  Original model where substrate had to fit perfectly into active site
• Induced fit model


  More realistic model where enzyme changes shape slightly to better fit the substrate
• The active site is complementary to the substrate
• The induced fit model is like putting your hand into a rubber glove - the glove molds to your hand
• Most chemical reactions in living cells are naturally quite slow
• Increasing temperature to speed up reactions is not feasible as it requires a lot of energy, can damage cells, and speeds up unwanted reactions
• Catalysts increase the speed of chemical reactions without being changed or used up in the process
• Enzymes are a type of biological catalyst made by living organisms