The results of freezing and dehydration of horseradish peroxidase

Explanations of the mechanism of freezing injury have included the one that freezing may result in dehydration of enzymes. This hypothesis has been examined by comparing the effects of freezing and dehydration on horseradish peroxidase.It was found that freezing and dehydration reduce the activity of peroxidase when compared with the native enzyme. Polyvinyl pyrrolidone and increased protein concentration protect the enzyme against loss of activity in both treatments, Protein-protein interactions exclude water, and this mechanism is suggested to stabilize peroxidase and protect against desiccation. Polyvinyl pyrrolidone may protect against freezing by reducing dehydration through reduced vapor-pressure difference or may stabilize by a protein-polymer interaction.