脲和盐酸胍诱导的卵清溶菌酶分子去折叠过程中各稳定构象态的分布和过渡  

Distribution and Transition of Stable Conformations of Hen Egg White Lysozymes in Their Unfolding Induced by Urea and Guanidine Hydrochloride Solutions

作　　者：张潭[1] 边六交[1] 

机构地区：[1]西北大学生命科学学院,西安710069

出　　处：《高等学校化学学报》2011年第7期1497-1505,共9页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:21075097)资助

摘　　要：以内源荧光光谱和荧光相图法研究了脲和盐酸胍诱导的卵清溶菌酶分子的去折叠过程,结果表明,当变性液中脲和盐酸胍的浓度分别约为4.0和3.0 mol/L时,卵清溶菌酶分子的去折叠过程均存在一个折叠中间态,这两个去折叠过程均符合"三态模型".在卵清溶菌酶分子"三态"去折叠过程的基础上,通过变性剂分子和卵清溶菌酶分子之间的缔合-解离作用,给出了一个定量描述此去折叠过程中卵清溶菌酶分子残余活性率随溶液中脲和盐酸胍浓度变化的方程.该方程包含两个特征展开参数,一个是蛋白质分子从一个稳定构象态过渡到另一个稳定构象态的热力学平衡常数k,另一个是在此过渡过程中平均每个蛋白质分子所结合的变性剂分子数目m.通过这两个特征展开参数能够定量描述脲和盐酸胍诱导的卵清溶菌酶分子天然态、折叠中间态和完全展开态随变性液中脲和盐酸胍浓度的分布和过渡.The unfolding of hen egg white lysozymes induced by urea and guanidine hydrochloride was studied by intrinsic fluorescence emission spectra and fluorescence phase diagram.The results show that during these two unfolding procedures,a stable intermediate of hen egg white lysozymes separately existed at about 4.0 mol/L of urea or 3.0 mol/L of guanidine hydrochloride in denaturation solution,and both of these two unfolding followed a three-state model.Based on the three-state model,an equation which described the residual activity ratios of egg white lysozymes under different concentrations of urea and guanidine hydrochloride in denaturation solution was presented and through this equation two characteristic unfolding parameters,the thermodynamic equilibrium constant k of the conformational transition of egg white lysozyme molecules from one conformational state to another one and the number m of denaturant molecules associated with an egg white lysozyme molecule during these conformational transitions,can be simultaneously derived.Furthermore,by means of these characteristic unfolding parameters,the distribution and transition of stable conformations of egg white lysozyme molecules under different concentrations of urea and guanidine hydrochloride in denaturation solution can be well described.

关 键 词：卵清溶菌酶 去折叠 脲 盐酸胍 特征展开参数 

分 类 号：O657.3[理学—分析化学]