Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

3.2.83 · Enzymes

Enzyme Activity- Immobilised v Free — Cambridge AS & A Level Biology 9700 Revision Notes & Topical Questions

5 min read 7 parts Lesson 16 of 17 Unit quiz

📚 Cambridge AS & A Level Biology 9700 Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
0%read
Lesson summary

3.2.8 Enzyme Activity: Immobilised v Free — CAMBRIDGE AS & A LEVEL BIOLOGY 9700 — REVISION NOTES notes: Compare free and immobilised enzymes and describe an application in lactose-free milk.Free enzymes — added to a solution, with substrate added directly or the enzyme added to s…

  • Uncontaminated product
  • Lactose intolerance
  • Free enzymes — added to a solution, with substrate added directly or the enzyme added to substrate in a controlled way
  • Immobilised enzymes — bound to an inert, stationary, insoluble material such as alginate
  • Method — the substrate is passed over the immobilised enzyme and the product is collected
  • Reuse — the enzyme can be used many times, which is efficient and cost-effective

Part 1 of 5Free and immobilised enzymes

Free enzymes
  • Free enzymes added to a solution, with substrate added directly or the enzyme added to substrate in a controlled way.
Immobilised enzymes
  • Immobilised enzymes bound to an inert, stationary, insoluble material such as alginate.
Method
  • Method the substrate is passed over the immobilised enzyme and the product is collected.

Part 2 of 5Advantages of immobilised enzymes

Uncontaminated product
  • Uncontaminated product no enzyme enters the product, so no filtering or further processing is needed.
Reuse
  • Reuse the enzyme can be used many times, which is efficient and cost-effective.
Stability
  • Stability immobilised enzymes tolerate temperature and pH changes better.

Part 3 of 5Lactose-free milk

Lactose
  • Lactose a disaccharide that lactase hydrolyses to glucose and galactose.
Lactose intolerance
  • Lactose intolerance about 5–10% of the UK population are lactose intolerant.

Part 4 of 5Making lactose-free milk

1
Immobilise lactase in alginate beads.
2
Pack the beads into a column.
3
Run milk through the column.
4
The lactase hydrolyses lactose to glucose and galactose.
5
The milk leaving the column is lactose-free and can be used for other dairy products.

Part 5 of 5More from the specification

More from the specification
Immobilised enzyme thermal stability
  • Immobilised enzyme thermal stability entrapping enzymes in calcium alginate beads provides a practical means to enhance thermal resistance and enable reuse.
Michaelis-Menten Constant (Km) and Enzyme Affinity
  • The Michaelis-Menten constant Km represents the substrate concentration at which reaction velocity is half of Vmax, providing an inverse measure of enzyme affinity for its substrate.
Competitive vs. Non-Competitive Inhibitors
  • Competitive inhibitors resemble substrate molecules and bind reversibly to the active site,
    • (increasing Km without changing Vmax)
  • whereas non-competitive inhibitors bind allosteric sites to alter active site shape.
    • (lowering Vmax without changing Km)
Substrate Concentration and Collision Frequency
  • Increasing substrate concentration increases the frequency of successful collisions with free enzyme active sites, elevating the rate of enzyme-substrate complex formation until saturation is reached.
Immobilised vs. Free Enzymes in Biotechnology
  • Immobilising enzymes in calcium alginate beads increases resistance to extreme pH and temperature, facilitates continuous reuse,
  • and prevents protein contamination in downstream products compared to free enzymes.
Non-competitive inhibitor
  • An inhibitor that binds elsewhere and changes the active site.
Enzyme-substrate complex
  • The temporary structure formed when a substrate binds to an enzyme's active site.
Inhibitor
  • A molecule that reduces enzyme activity.
Optimum
  • The temperature or pH at which activity is highest.
Affinity
  • How readily haemoglobin binds oxygen.
Buffer
  • A substance that resists pH change by absorbing or releasing H+.
Substrate concentration
  • The amount of substrate per unit volume.
Enzyme concentration
  • The amount of enzyme per unit volume.
Active site
  • The region of an enzyme with a shape into which the substrate fits.
Successful collision
  • A collision with enough energy and correct orientation.

Key terms

TermMeaning
Free enzymeAn enzyme dissolved in a solution.
Immobilised enzymeAn enzyme bound to an inert insoluble support.
AlginateA material used to form beads that trap enzymes.
LactaseThe enzyme that hydrolyses lactose.
LactoseA disaccharide of glucose and galactose.
Lactose intoleranceInability to digest lactose properly.

Avoid these mistakes

1
Saying immobilised enzymes are used up — they can be reused.
2
Saying free enzymes give uncontaminated product — they remain in the product.
3
Saying lactase makes lactose — it breaks lactose down.
4
Saying alginate beads are reactants — they are an inert support.

Last updated: