Irreversible thermal denaturation of Trichoderma reesei endo-1,4-β-xylanase II and its three disulfide mutants characterized by differential scanning calorimetry

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• 作者：Janne Jä ; nis ; Juha Rouvinen ; Pirjo Vainiotalo ; Ossi Turunen ; Valery L. Shnyrov
• 关键词：Xylanase ; Disulfide ; Thermal stability ; Differential scanning calorimetry
• 刊名：International Journal of Biological Macromolecules
• 出版年：2008
• 出版时间：1 January 2008
• 年：2008
• 卷：42
• 期：1
• 页码：75-80
• 全文大小：175 K

文摘

Kinetic as well as energetic aspects of the thermal denaturation of Trichoderma reesei endo-1,4-β-xylanase II (TRX II) and its three thermostable disulfide mutants were characterized by means of differential scanning calorimetry (DSC) in different solution conditions. The calorimetric transitions were strongly scan-rate dependent, characteristic for an irreversible, kinetically controlled protein denaturation. The DSC-determined T*-values (the temperature at which the denaturation rate constant equals 1 min⁻¹), and the activation free energies for the transitions are consistent with the apparent transition temperatures of TRX II determined earlier by mass spectrometry. Protein aggregation, connected with the irreversibility of the transitions, was present in all cases but was less pronounced with the mutants as well as highly dependent on experimental conditions.