Properties

• Proteins with tertiary structures so gives positive reaction ( purple ) with biuret solution
• 1. Enzymes are substrate specific

  • each enzyme only catalyses one reaction due to its specific tertiary structure being complimentary to only one substrate
  • substrate must be the right shape but also must mak the active site chnage in correct way — induced fit
• 2. enzymes are sensitive to environmental conditions like temperature and pH

  • each enzyme has optimal temperature and pH which it works best , at higher temp and pH than the optimum enzymes are denatured

  loose their their tertiary structure

  • at lower than optimum temperature the kenetic energy of molecule is decreased which lowers the rate of reaction
• temperature 


  up to optimum temp a Rosie in temperature increases reaction rate ( increase of 10 degrees doubles rate )

  beyond optimum the rate o reaction decreases rapidly
• at low temperature 


  enzyme and substrate molecules have very little kinetic energy

  move slowly and rarely collide

  few enzyme - substrate complexes and therefore few product molecules form

  rate of reaction very low
• up to optimum temperature

  • temperature increases the kinetic energy of the enzyme and substrate molecules increase
  • move quickly and collide more , energy of collisions increases so they are more likely to be successful
  • many enzyme substrate complexes and product molecules form
  • reaction rate increases
• above optimum temperature

  atoms in enzyme vibrate soo much that the 3D structure is lost

  • vibrations cause ionic bonds, hydrogen bonds and disulphide bridges to breaks so the 3D structure becomes unstable
  • shape of active site is changed , and substrate can no longer bind to enzyme
  • no enzyme substrate complexes can form so no product made
  • enzyme denatured
  • loss of tertiary structure means loss of function
• pH

  Changes in pH affects the ionisation of the side groups in the amino acid residue and changes mean ionic and H bonds break and so looses tertiary structure

  • alters shape of active site - denatures