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Freeze-thawing induced structural and functional changes in glucose oxidase.
O A Nardid1, E D Rozanova2, E I Naumenko2
1Institute for Problems of Cryobiology and Cryomedicine, National Academy of Sciences of Ukraine, Kharkov, Ukraine. olnard@mail.ru.
Cryo Letters
|May 30, 2014
Summary
Studying glucose oxidase (an enzyme) reveals that freezing rates significantly impact its structure and activity. Rapid freezing preserves enzyme activity better than slow freezing, especially at higher enzyme concentrations.
Area of Science:
- Biochemistry
- Enzymology
- Protein Science
Background:
- Glucose oxidase serves as a model biomacromolecule for low-temperature studies.
- Understanding temperature effects on biomacromolecules is crucial for various applications.
Purpose of the Study:
- To investigate the impact of freeze-thawing on isolated and immobilized glucose oxidase.
- To analyze the effects of different freezing rates on enzyme conformation and activity.
Main Methods:
- Studied glucose oxidase isolated and immobilized via glutaraldehyde cross-linking.
- Examined the influence of varying freezing rates (2°C/min vs. 100°C/min) on enzyme properties.
- Assessed conformational changes and activity after multiple freeze-thaw cycles.
Main Results:
- Slow freezing (2°C/min) caused significant protein aggregation, reduced activity, and conformational changes in polar/hydrophobic regions.
- Rapid freezing (100°C/min) induced conformational changes mainly in polar regions, with minimal aggregation and increased activity.
- Higher glucose oxidase concentrations mitigated low-temperature-induced destabilization.
Conclusions:
- Freezing rate critically affects glucose oxidase stability and activity.
- Rapid freezing is preferable for preserving glucose oxidase activity, especially at higher concentrations.
- Glutaraldehyde cross-linking at slow cooling rates alters polar regions, enhancing enzyme activity.
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