荧光光谱法研究牛血清蛋白在盐酸胍体系中的变性

Denaturation Study of Bovine Serum Albumin Induced by Guanidine Chloride with Fluorescence Spectroscopy

应用荧光光谱技术,对盐酸胍与牛血清蛋白在30℃水溶液中的结合作用及造成牛血清蛋白变性的过程进行了研究,考察了盐酸胍诱导牛血清蛋白变性时荧光强度和峰位的变化规律,并计算出伸展分数fu,变性平衡常数Ku,伸展吉布斯自由能ΔGu,衡量蛋白质对变性剂稳定性的参量ΔGH2O,衡量蛋白质变性协同性的参量m和变性中点c1/2。研究结果表明,盐酸胍通过直接和间接的两种作用造成牛血清蛋白变性,伸展分数fu随盐酸胍浓度的变化呈3个阶段,当盐酸胍浓度达6.0 mol.L-1时,伸展分数fu约为1,结构完全打开,牛血清蛋白完全变性。

The interaction between guanidine chloride and bovine serum albumin（BSA） in aqueous solution as well as the denaturation process of BSA were studied with fluorescence spectroscopy at 30 ℃ and two pHs.The fluorescence spectroscopic data were analyzed with the methods described by Pace.The unfolding fraction（fu）,denaturation equilibrium constant（Ku） and free energy of unfolding（ΔGu）of protein were calculated.The transition midpoint（c1/2）,steepness of the transition region（m） and free energy of unfolding（ΔGH2O） were also obtained.The results indicated that the denaturation of BSA was induced by guanidine chloride through direct and indirect effects,the interaction between guanidine chloride and BSA was divided into three stages.When the guanidine chloride concentrations reached 6.0 mol·L-1,the unfolded fraction fu was about 1 and the BSA was completely denaturated.