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[Urease immobilization on macroporous silicas]
Prikladnaia Biokhimiia I Mikrobiologiia
|May 1, 1983
Summary
Immobilizing urease on macroporous silica supports with optimized pore sizes and using purified enzyme yields highly active preparations. Freeze-drying with sorbitol maintains the activity of these immobilized urease materials.
Area of Science:
- Biocatalysis
- Enzyme Immobilization
- Materials Science
Background:
- Urease is a crucial enzyme for various industrial and biotechnological applications.
- Efficient immobilization of urease is key to enhancing its stability and reusability.
- Macroporous silica supports offer advantages for enzyme immobilization due to their high surface area and tunable pore structures.
Purpose of the Study:
- To optimize the immobilization of urease onto macroporous silica supports.
- To investigate the impact of support properties and enzyme purity on immobilized urease activity.
- To develop stable and highly active immobilized urease preparations for practical applications.
Main Methods:
- Urease immobilization on macroporous silicas using gamma-aminopropyl triethoxysilane and glutaraldehyde.
- Varied protein loading, support pore structure (silica gel, silochrome), and enzyme purity.
- Controlled and measured enzymic activity of immobilized preparations.
- Optimized pore diameter (70-90 nm) and specific surface area (approx. 70 m²/g) for supports.
- Utilized purified urease for higher activity preparations.
- Employed freeze-drying with sorbitol for stable dry preparations.
Main Results:
- Retained approximately 35% of specific activity after immobilizing large quantities of urease (3 mg protein/m²).
- Maximum activity per unit weight of support achieved with silicagels and silochromes having mean pore diameters of 70-90 nm and specific surface areas around 70 m²/g.
- Highly active immobilized urease preparations (17,000 U/g dry support) were obtained using purified urease.
- Freeze-dried preparations in the presence of sorbitol demonstrated retained activity.
Conclusions:
- Optimized macroporous silica supports (70-90 nm pore diameter, ~70 m²/g surface area) are effective for high-activity urease immobilization.
- Using purified urease and optimizing immobilization conditions significantly enhances the activity of the final biocatalyst.
- Freeze-drying in the presence of sorbitol provides a viable method for producing stable, dry immobilized urease preparations.