Ahmad F, Taneja S, Yadav S, Haque S E
J Biochem. 1994 Feb;115(2):322-7. doi: 10.1093/oxfordjournals.jbchem.a124336.
Denaturations of ribonuclease A, lysozyme, and cytochrome c by guanidine hydrochloride (GdnHCl), urea, and GdnHCl-urea mixture were studied at constant temperature and pH to assess the functional dependence of denaturational free energy change (delta GD) on denaturant concentration over an extended GdnHCl concentration range. Conventional analysis of GdnHCl-induced transition curve exhibits a linear plot of delta GD versus [GdnHCl] in the transition zone. To extend delta GD measurements beyond this narrow concentration range, GdnHCl-induced unfolding was measured in the presence of different concentrations of urea. delta GD values from these measurements were corrected for the effect of urea on the free energy change using the appropriate relation. The corrected delta GD data were mapped onto the delta GD versus [GdnHCl] plot. For each protein, the dependence of free energy change on denaturation was found to be linear over the full GdnHCl concentration.
在恒定温度和pH条件下，研究了盐酸胍（GdnHCl）、尿素以及GdnHCl-尿素混合物对核糖核酸酶A、溶菌酶和细胞色素c的变性作用，以评估在较宽的GdnHCl浓度范围内变性自由能变化（ΔGD）对变性剂浓度的函数依赖性。对GdnHCl诱导的转变曲线进行常规分析时，在转变区ΔGD与[GdnHCl]呈现线性关系。为了将ΔGD的测量范围扩展到这个狭窄的浓度范围之外，在不同浓度尿素存在的情况下测量了GdnHCl诱导的去折叠过程。利用适当的关系式，对这些测量得到的ΔGD值进行了尿素对自由能变化影响的校正。将校正后的ΔGD数据绘制在ΔGD与[GdnHCl]的图上。对于每种蛋白质，发现在整个GdnHCl浓度范围内，自由能变化对变性的依赖性都是线性的。
