Enzyme Action

• Enzymes are biological catalysts
• Enzymes are globular proteins at the tertiary level
• Catalysts alter the rate of reaction without undergoing permanent change so they can be used again and again
• Enzymes are effective in small amounts
• Most enzyme controlled reactions are reversible
• Enzymes are reaction specific because they only react with a particular molecule
• The active site is the region of the enzyme molecule where the substrate binds
• Most enzymes are denatured by high temperatures or extreme pH
• Conditions for a chemical reaction to take place

  • substrates collide with enzyme with sufficient kinetic energy
  • energy of the products must be lower than the substrates
  • initial boost of energy required - activation energy
• Activation Energy = minimum amount of energy needed for a reaction to occur
• Active site of the enzyme and the substrate molecules are complementary to each other
• Substrates and enzymes form enzyme-substrate complexes
• Lock and key method

  • substrate molecule fits perfectly into active site of enzyme
• Induced fit model

  • active site is complementary to the shape of the substrate and changes to accommodate it