Accurate structural analysis of natively unfolded proteins by the solution X-ray scattering

为研究未折叠蛋白的结构特征，提出了一种生成多肽构象的新方法。通过将该方法的预测结果与溶液x射线散射测量结果进行比较，分析了高浓度变性剂溶液中蛋白质的x射线散射。通过对残基数和多肽链Kratky曲线形状对均方半径的依赖性分析，证实了高浓度变性剂溶液是一种较好的溶剂。我们还发现，对于再现实验数据的构象系，主链二面角位于α-区的概率必须在20% ~ 40%之间。

A new method for generating polypeptide conformations has been developed for studying structural characteristics of unfolded proteins. Those of proteins in high-concentration denaturant solution were analyzed by comparing predictions from this method with results from solution X-ray scattering measurement. Analysis of the dependence of mean square radius on the number of residues and the shape of Kratky profiles for polypeptide chains has confirmed that a high-concentration denaturant solution serves as a good solvent. We found also that, for a conformational ensemble to reproduce experimental data, the probability that main-chain dihedral angles are in the α-region must be in the range of 20 to 40%.