Enzymes

• Enzymes


  Important proteins that speed up the rates of reaction such as in photosynthesis, respiration and protein synthesis
• Enzymes


  • Biological catalysts that lower the activation energy of the reaction, hence speeding it up
  • Unchanged at the end of the reaction and can be reused
• How enzymes work


  1. Enzymes work in conjunction with substrates

  2. Enzymes and substrates collide at the right speed and orientation so that the substrate fits into the enzyme at the active site

  3. Collision theory dictates that collision must occur with sufficient energy and in a specific orientation for a reaction to occur

  4. Enzymes are specialized, their active site matches the shape of a specific substrate that they can react with

  5. Enzymes and substrates fit together using a lock and key mechanism

  6. Once the substrate is in the active site, the reaction takes place, the required product is produced and the enzyme releases itself and carries on moving around
• Enzymes breaking down substrates

  • Protease breaks down proteins into amino acids
  • Carbohydrase breaks down carbohydrates into glucose
  • Lipase breaks down fats into fatty acids and glycerols
• Hydrogen peroxide


  Often formed as a result of reactions in cells, and if left to build up, is harmful
• Catalase enzymes


  Break down hydrogen peroxide into harmless water and oxygen
• Enzymes


  • Sensitive, each enzyme has optimum conditions under which it works best
  • Need enough substrate around, high enough substrate concentration for the reaction they catalyze
  • If there is too much product around, the reaction slows because the enzymes and substrates have less chance of bumping into each other, so the product needs to be removed for a higher rate of reaction
  • Have optimum pH and temperature conditions, up to a point an increase in temperature causes increased rates of reaction because there is more heat energy, more energy means more collisions, however above a certain temperature the rate drops off due to denaturation
  • Need enough enzymes around for the rate of reaction to be optimized
• Uses of enzymes in day-to-day life

  • Protease and lipase enzymes used in biological washing powders to remove proteins and fats from stains
  • Pectinase used to break down the cells in fruit when making juice so that more juice is released