Glucose oxidase-dextran conjugates with enhanced stabilities against temperature and pH

Area of Science:

• Biochemistry
• Biotechnology
• Polymer Science

Background:

• Glucose oxidase (EC 1.1.3.4) is crucial in biosensors and biocatalysis.
• Improving enzyme stability under various conditions is essential for practical applications.
• Dextran, a natural hydrophilic polymer, offers potential for enzyme immobilization.

Purpose of the Study:

• To achieve multipoint covalent bonding of glucose oxidase to dextran.
• To optimize conjugation procedures for enhanced temperature and pH stability.
• To evaluate the biotechnological feasibility of the modified enzyme.

Main Methods:

• Purified glucose oxidase was conjugated with different molecular weight dextrans (17.5, 75, 188 kD) at various molar ratios.
• Enzyme activity and thermal resistance of conjugates were determined across a temperature range (25-80°C) at pH 7.
• pH stability was assessed at elevated temperatures.

Main Results:

• Conjugation with dextran enhanced the thermal stability of glucose oxidase.
• The conjugate prepared with 75 kDa dextran at a 1:5 molar ratio exhibited the highest thermal resistance.
• This optimal conjugate retained activity up to 80°C at pH 7 and showed activity across a pH range of 4.0-7.0 at high temperatures.

Conclusions:

• Multipoint covalent bonding of glucose oxidase to 75 kDa dextran significantly improves its thermal and pH stability.
• The optimized conjugate demonstrates robustness for potential use in biotechnological applications.
• This approach offers a viable strategy for enzyme stabilization and functional enhancement.