Acta Chimica Sinica ›› 2008, Vol. 66 ›› Issue (5): 515-519. Previous Articles     Next Articles

Original Articles

牛血清蛋白在盐酸胍和尿素体系中变性的微量热研究

李向荣*,1,2,郭伟2,卢雁1   

  1. (1河南师范大学化学与环境科学学院 新乡 453007)
    (2新乡医学院基础医学院化学教研室 新乡 453003)
  • 收稿日期:2007-06-02 修回日期:2007-09-20 出版日期:2008-03-14 发布日期:2008-03-14
  • 通讯作者: 李向荣

Denaturation Study of Bovine Serum Albumin Induced by the Guanidine Chloride or Urea by Microcalorimetry

LI Xiang-Rong*,1,2 ,GUO Wei2 ,LU Yan1   

  1. (1 College of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453007)
    (2 Department of Chemistry, School of Basic Medicine, Xinxiang Medical College, Xinxiang 453003)
  • Received:2007-06-02 Revised:2007-09-20 Online:2008-03-14 Published:2008-03-14
  • Contact: LI Xiang-Rong

The denaturation of bovine serum albumin (BSA) induced by guanidine chloride or urea at different pH values was studied by isothermal microcalorimetry measurements at 30 ℃. The simple bonding model, which was developed by Privalov, was employed to obtain the apparent bonding constant K, the apparent singular bonding Gibbs bonding energy ΔG and the total Gibbs energy ΔG(a) between the protein and denaturant from analyzing the calorimetric data. Furthermore, the linear extrapolation at the midpoint of transition was employed to determine the apparent denaturation enthalpy ΔHd. The results showed that, for guanidine chloride, the bonding between BSA and guanidine chloride could proceed more easily in an alkaline condition, and the apparent denaturation enthalpy ΔHd of BSA by guanidine chloride was 350 kJ•mol-1 at pH 6.97 and 7.05, while it was 275 kJ•mol-1 at pH 9.30, which indicated that BSA was more stabilized in a neutral condition. But for urea, the bonding between BSA and urea would proceed more easily in an acidic condition, and the apparent denaturation enthalpy ΔHd of BSA by urea was 295 kJ•mol-1 at pH 6.97, while 230 kJ•mol-1 at pH 7.05 and 9.30. The results indicated that the expanding degree of BSA in the two denaturants was different.

Key words: bovine serum albumin, isothermal microcalorimetry, guanidine chloride, urea, denaturation