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[Investigation of membrane permeability of carp spermatozoa for water molecules].

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Freeze-thawing induced structural and functional changes in glucose oxidase.

O A Nardid1, E D Rozanova2, E I Naumenko2

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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.

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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.