Module 4 Lesson 2 Flashcards
Isolated or purified enzyme confined or localized in a specified volume of space.
Immobilized enzymes
explain the diagram of Immobilized Enzymes
The diagram illustrates a setup for using immobilized enzymes. Substrate enters at the top of a column filled with alginate pellets containing immobilized enzymes. As the substrate flows through the column, it interacts with the enzymes, facilitating the reaction. A tap at the bottom controls the flow rate, affecting reaction efficiency. The resulting products exit at the bottom, ready for collection. This system ensures enzyme stability, reusability, and efficient catalysis.
Why are enzymes immobilized?
Enzymes are immobilized to enhance their stability, reusability, and efficiency. Immobilization prevents the enzymes from being washed away during reactions, allowing them to be used repeatedly, which reduces costs. It also provides better control over reaction conditions, facilitates separation of enzymes from products, and can improve enzyme activity or stability under various conditions. Additionally, immobilized enzymes are easier to handle and integrate into industrial processes.
Disadvantages of Immobilized cell
Immobilized enzymes have several disadvantages. Setting up the system requires additional time, specialized equipment, and materials, making it more complex compared to free enzymes. These enzymes may also exhibit reduced activity since they cannot mix freely with the substrate. Contamination poses a significant risk, as it can be costly and necessitate halting the entire system for cleaning and recovery. Furthermore, enzymes can leak out of the immobilization medium, especially when using simpler materials like gelatin and agar, which are more prone to leakage.
What are the Immobilized Methods
Adsorption
Covalent Attachment
Cross-linking
Entrapment
Microencapsulation
The simplest method of immobilizing enzymes.
However, the bonding strength is weak, low enzyme loading, and sensitivity to pH, ionic strength, and temperature.
Commonly employed adsorbents are alumina, calcium carbonate, glass plates, diatomaceous earth, carbon, and clays.
Adsorption
Commonly employed water-insoluble supports for the covalent attachment of enzymes.
Synthetic supports such as acrylamide-based polymers, styrene-based polymers, or anhydride-based polymers, and natural supports such as agarose, dextran, chitin and starch.
Covalent Attachment
is most preferred than organic materials because of the potential reuse, non-toxicity, good half-life of enzymes using the inorganic support, and the ease of using this to any enzyme system.
Inorganic support
Water-insoluble enzymes can be prepared by using multifunctional agents such as.
glutaraldehyde
Enzymes are entrapped within cross-linked polymers by forming a highly cross- linked network of polymer such as a polyacrylamide gel system.
Entrapment
involves packaging the enzyme in tiny, usually spherical capsules ranging from 5-300µm diameter in semi-permeable (permanent) or liquid (nonpermanent) membranes.
Microencapsulation
Compare and contrast the two methods of Microencapsulation
The interfacial polymerization technique and the coacervation-dependent method both produce enzyme microcapsules through vigorous stirring, forming enzyme droplets surrounded by semi-permeable membranes. In interfacial polymerization, the enzyme solution contains one component of the membrane-forming material, with additional reagents added via an organic solvent. In contrast, the coacervation method uses organic solvents containing all polymer components. Both methods result in semi-permeable membranes, typically made from materials like cellulose nitrate or polystyrene, which harden around the droplets before washing and transfer. However, the interfacial method requires sequential addition of reagents, while coacervation simplifies this by including all components from the start.
Compare and contrast the Main enzyme immobilization methods.
The main enzyme immobilization methods differ in their binding nature, advantages, and disadvantages. Physical adsorption, involving weak interactions, is simple and cost-effective but suffers from nonspecific adsorption and desorption. Affinity-based methods, relying on specific affinity bonds, offer high selectivity and orientation but are expensive. Covalent binding provides stability and prevents enzyme leakage but is irreversible, with potential activity loss. Entrapment, which traps enzymes within a polymer network, is versatile but faces limitations like enzyme leakage and restricted mass transfer. Cross-linking stabilizes biocatalysts but is less effective in packed systems and also suffers from activity loss and mass transfer issues.
First immobilized enzyme
from Aspergillus oryzae
Resolution of synthetic racemic D-L amino acids
Aminoacylase
High-fructose corn syrup
Glucose isomerase
