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Factors affecting malate dehydrogenase activity in freezing-thawing processes
1Department of Biochemistry and Physiology, University of Barcelona, Spain.
Summary
Freezing and thawing malate dehydrogenases in specific buffers can cause significant activity loss due to protein aggregation. Metabolites and buffer conditions influence this enzyme instability.
Area of Science:
- Biochemistry
- Enzymology
- Protein Chemistry
Background:
- Malate dehydrogenases (MDH) are crucial enzymes in cellular metabolism.
- Enzyme stability during storage and processing is vital for biochemical applications.
- Previous studies indicate protein sensitivity to cryopreservation.
Purpose of the Study:
- To investigate the impact of freeze-thawing on malate dehydrogenase activity.
- To identify factors influencing enzyme inactivation during cryopreservation.
- To understand the mechanism of activity loss in MDH.
Main Methods:
- Enzyme activity assays of malate dehydrogenases from various sources.
- Freeze-thaw cycles in 100 mM sodium phosphate buffer (pH 7.4) with chaotropic ions.
- Analysis of effects of metabolites, protein concentration, and buffer composition.
Main Results:
- Malate dehydrogenases exhibited varied responses to freeze-thawing.
- Activity loss was significantly influenced by chaotropic ions, metabolites, and buffer conditions.
- The primary cause of inactivation was the formation of high molecular weight aggregates.
Conclusions:
- Freeze-thawing in the presence of chaotropic ions leads to malate dehydrogenase inactivation.
- Protein aggregation is the main mechanism behind activity loss.
- Optimizing buffer composition and metabolite presence can mitigate freeze-thaw-induced enzyme instability.