Enzymes

• Catalyst

  a substance which increases the speed of reaction, without being changed or used up
• Substrate

  A molecule that is changed in a reaction
• Active site

  Where a substrate joins on to the enzyme
• Substrate

  The molecule which the enzyme works on
• The substrate molecules bind to the enzyme active site because the shape of both are complementary
• The enzyme active site has a specific shape and usually only binds to one type of substrate. We therefore they enzymes are specific
• When the substrate binds successfully we say an enzyme-substrate complex has formed
• Once the enzyme-substrate complex has formed, a reaction takes place
• Enzymes are never used up
• Enzymes can be destroyed or denatured by excessive heat
• Too much heat breaks bonds holding the enzyme together and the shape of the active site changes
• Enzymes are all:

  -made of protein

  -affected by heat

  -affected by pH

  -not changed and can be reused
• Proteases

  Break down protein to amino acids
• Carbohydrases

  Break down carbohydrates to sugars
• Lipeases

  Break down lipids into glycerol and fatty acids
• Affecting enzyme activity:

  -temperature

  -pH

  -enzyme concentration

  -substrate concentration
• Raising the temperature too high can denature the enzyme so the substrate doesnt fit anymore
• As temperature rises, enzymes work faster. As temperature falls, enzymes work slower. The temperature where Enzymes work best is their optimum temperature. At very high temperatures, enzymes because denatured and the shape of the active site changes permanently meaning they no longer work. Enzymes in the human body generally work best at around 37 degrees
• The pH which enzymes work best is the optimum pH. Enzymes in your stomach work best at a pH of 1-2. Enzymes in you mouth work best at around 7. A small pH change affects how well they work but doesn't change them. A large pH change will denature the enzyme and it can never work again.
• Catalase is one of the fastest enzymes and is found in most organisms. Liver tissue is rich in Catalase. Catalase breaks down toxic Hydrogen Peroxide (made inside cells) into harmless water and oxygen