Characteristics of Enzymes

• Lock and Key Hypothesis


  1. depressions on the enzyme molecule form the active site.
  2. The specific substrate binds with the enzymes active site as it has a shape complementary to the active site forming the enzyme-substrate complex. A chemical reaction occurs on the substrate molecule.
  3. Products formed leave the enzyme’s active site. The enzyme molecule itself remains chemically unchanged and the active site is available for another substrate molecule to bind to it

  
• phenylketonuria


  • Phenylketonurics are people who suffer from a disorder called phenylketonuria (PKU).
  • They are not able to breakdown the amino acid phenylalanine.
  • Phenylalanine level builds up in the blood and may affect the intellect and cause other other health issues.
  • Aspartame, a common sugar substitute, contains phenylalanine
  • In PKU sufferers, the enzyme produced is misfolded due to a defective gene.
• Temperature (Enzymes)

  • At low temperature, enzyme activity is low as the kinetic energy of molecules is low. Enzymes are inactive. Chances of effective collision between enzyme and substrate molecules is very low.
  • Enzyme activity is fastest at the optimum temperature.
  • As temperature increases above the optimum temperature, enzyme starts to denature. Rate of reaction decreases rapidly.

  
• Denature

  • Enzymes denature upon exposure to temperature above its optimum temperature
  • Denaturation involves the change in the enzymes’ 3D structure.

  
• pH (Enzymes)

  • The optimum pH in which an enzyme works best varies among different enzymes
  • Extreme acidity or alkalinity of a solution will cause enzymes to denature.

  
• Catalase


  refers to a specific enzyme that increases the rate of decomposition of hydrogen peroxide to water.