immobilised enzymes

• In which industries are enzymes used on a commercial scale?

  Food, pharmaceutical, and agrochemical industries
• What are immobilised enzymes?

  Enzymes fixed on an inert matrix
• What is an example of an inert matrix for immobilising enzymes?

  Alginate beads
• Why is immobilising enzymes on a membrane often preferable?

  It allows direct contact with the substrate
• What enzyme might you have used with alginate beads in school?

  Lactase or pectinase
• How does the diffusion of substrate molecules differ between alginate beads and membrane immobilisation?

  Substrates diffuse slower in alginate beads
• What are the advantages of using immobilised enzymes?

  1. No product contamination
  2. Can be recovered and reused
  3. Requires small enzyme quantities
  4. Greater stability at higher temperatures
  5. Catalyse reactions over wider pH range
  6. Multiple enzymes can be used
  7. Greater process control
  8. Suitable for continuous processes
• What percentage of the world's population is lactose intolerant in adulthood?

  About three-quarters
• What does lactase do to lactose?

  Breaks it into glucose and galactose
• How does lactose diffuse in the immobilisation process?

  It diffuses into the alginate matrix
• What happens to glucose and galactose after they are formed?

  They diffuse out of the alginate beads
• How can flow rate affect enzyme-substrate interactions?

  Decreasing flow allows more contact time
• Why are smaller alginate beads used?

  To increase surface area for diffusion
• What temperature range shows the greatest activity for free enzymes?

  Between 20 - 40 °C
• What happens to enzyme activity as temperature increases?

  Kinetic energy increases, leading to more collisions
• What occurs to enzymes between 40 - 60 °C?

  They become denatured due to broken bonds
• How does alginate gel support enzyme activity?

  It maintains the shape of the active site
• Why would a fruit juice manufacturer choose membrane-bound enzymes at 60 °C?

  To produce the greatest yield of fruit juice
• How can the yield of fruit juice be increased further?

  By folding the membrane to increase active sites
• What is the function of biosensors?

  To detect biologically important molecules
• How do biosensors measure blood glucose concentration?

  Using immobilised enzymes on a gel membrane
• What role does the transducer play in a biosensor?

  It converts chemical change into an electrical signal
• What happens when urea molecules diffuse across the membrane in a biosensor?

  They form enzyme-substrate complexes with urease
• What product is formed when urease acts on urea?

  Ammonium ions
• What is the outcome of the chemical change detected by the biosensor?

  It generates an electrical signal for display