Acta Chimica Sinica ›› 2010, Vol. 68 ›› Issue (02): 194-198. Previous Articles     Next Articles

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等转化率法分析溶菌酶在添加剂影响下的热变性行为

曹小敏*,1,王志勇2,刘欲文2,汪存信2,田耘3   

  1. (1长沙环境保护职业技术学院 湖南 长沙 410004)
    (2武汉大学化学与分子科学学院 湖北 武汉 430072)
    (3湖南省环境监测中心站 湖南 长沙 410014)
  • 投稿日期:2009-06-05 修回日期:2009-08-02 发布日期:2010-03-17
  • 通讯作者: 曹小敏 E-mail:caograss2003@yahoo.com.cn
  • 基金资助:

    国家自然科学基金(No. 20373050 and 30600116)

Effect of Additive on the Thermal Denaturation of Lysozyme Analyzed by Isoconversional Method

Cao Xiaomin*,1 Wang Zhiyong2 Liu Yuwen2 Wang Cunxin2 Tian Yun3   

  1. (1Changsha Environmental Protection College, Changsha 410004)
    (2College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072)
    (3Environmental Monitoring Center of Hunan Province, Changsha 410014)
  • Received:2009-06-05 Revised:2009-08-02 Published:2010-03-17
  • Contact: CAO Xiao-Min E-mail:caograss2003@yahoo.com.cn

The thermal denaturation of lysozyme was studied as a function of different additive (sucrose, glucose, fructose, mannitol) concentrations, phosphate buffer concentration and scan rate using differential scanning calorimetry (DSC ) and analyzed by an isoconversional method. The denaturation temperature Tm increased with the increase of scan rate and the additive concentrations, while decreased with the increase of phosphate concentration. The phosphate accelerated the denaturation process of lysozyme and reduced the thermal stability of lysozyme, while the additives enhanced it. One part of the lysozyme denaturation process was irreversible in which aggregation occurred, and the other part was reversible in the presence of all additives. By the isoconversional method, it was showed that the apparent activation energy did not keep invariable at different conversion ratios (α) under all conditions, but decreased with the increase of α, which suggested that a simple reaction mechanism could not be used for the denaturation process. The denaturation was still not a process involving the two standard reversible states, but a multi-step process in the presence and the absence of all additives.

Key words: DSC, lysozyme, additive, isoconversional method, multi-step process