Combined effects of trehalose and cations on the thermal resistance of β-galactosidase in freeze-dried systems
The purpose of this study was to investigate the combined effects of trehalose and cations on the preservation of β-galactosidase in freeze-dried systems and their relationship to physical properties. Differential scanning calorimetry was employed to measure the glass transition temperature (T(g)) a...
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| Autores principales: | , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_03044165_v1473_n2-3_p337_Mazzobre |
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| Sumario: | The purpose of this study was to investigate the combined effects of trehalose and cations on the preservation of β-galactosidase in freeze-dried systems and their relationship to physical properties. Differential scanning calorimetry was employed to measure the glass transition temperature (T(g)) and the endothermal peak area, related to the amount of crystalline trehalose dihydrate present in the samples. In systems in which the trehalose matrix was humidified to conditions which allowed a high proportion of trehalose to crystallize, the enzyme was rapidly inactivated upon heating at 70°C. In these conditions the addition of CsCl, NaCl and particularly KCl or MgCl2, improved the enzyme stability with respect to that observed in matrices containing only trehalose. For a given moisture content, addition of salts produced very little change on the glass transition temperature; therefore the protective effect could not be attributed to a higher T(g) value. The crystallization of trehalose dihydrate in the humidified samples was delayed in the trehalose/salt systems (principally in the presence of Mg2+) and a parallel improvement of enzyme stability was observed. Copyright (C) 1999 Elsevier Science B.V. |
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