5 - Enzymes

• Enzymes that digest… -

  A) carbohydrase

  B) protease

  C) lipase

  D) pepsin

  E) amylase

  F) maltase

  
• Anatomy of an enzyme -

  1. enzyme - the biological catalyst
  2. substrate  - the substance that will bind to the enzyme
  3. active site - the site for substrate to bond
  4. enzyme-substrate complex - the term when enzyme and substrate are bonded together
  5. product - the substance that is produced from the enzyme action

  
• Temperature -

  • as temperature increases, reaction rate increases because of kinetic energy hence the rate of effective collisions increases
  • enzymes molecules start to permanently lose their shape at a high temp
  • this deforms their active site so the enzyme and substrate can’t fit together when the active site changes, the enzymes cannot bind with the substrate 
  • this is known as denaturation
  • hence no reaction will occur
  • enzymes aren’t denatured by low temperatures, they’re just slowed down and will work again when the temperature is suitable

  
• pH -

  • each enzymes have their own pH range, that they work best
  • when the pH increase or decreases drastically from an enzyme’s optimum level, the enzymes denature
  • protease = pH 2 (in stomach with hydrochloric acid)
  • amylase = pH 6.8 (in the mouth)
  • catalase = pH 7.6 (in plants, e.g. potato)
  • pancreatic lipase, pH 9 (in the duodenum)
• Catalyst:

  A substance that increases the rate of a chemical reaction and is not changed by the reaction
• Enzyme:

  Proteins that function as biological catalysts and are involved in all metabolic reactions