尿素诱导的蛋白质变性现象的研究

Research on Urea-induced Protein Denaturation

通过对典型蛋白质变性实验结果的分析,发现在蛋白质变性研究领域中普遍使用的二态模型所描述的过程,与真实蛋白质变性过程并不相符.在分析已有的实验结果的基础上,给出了反映蛋白质变性过程特征的新表示形式.这一形式表明蛋白质分子变性是一个构象渐变的过程,同时强调在一定浓度的尿素溶液中蛋白质分子均处于相同的构象态.从尿素分子与蛋白质肽链上的相邻二肽形成双氢键的假设出发,利用吸附反应动力学方法,得到了描述蛋白质变性特征的物理量与尿素浓度关系的表示式.结果表明理论值与实验值符合较好,说明建立的模型可较好地描述尿素导致的蛋白质变性现象.

The typical experimental data of protein denaturation are analyzed.It is found that the two-state model,which is used widely on the studies of protein denaturation,is not consistent with a true denaturation process.On the basis of analyzing the experimental results,a new expression that can reflect the feature of urea-induced denaturation is given.It indicates that protein denaturation is a sequential process for conformational changes.It is emphasized that protein molecules are in a certain conformational state at a fixed urea concentration.Assuming that two hydrogen bonds are formed between a urea molecule and two neighboring peptides of the polypeptide chain,the relationships between physical parameter and urea concentration are obtained by means of adsorption kinetic method.The results show that the theoretical predictions conform to experimental data.It manifests that the model can describe the characteristic of the urea-induced denaturation.