Ahmad F, Yadav S, Taneja S
Department of Chemistry, Jamia Millia Islamia, Jamia Nagar, New Delhi, India.
Biochem J. 1992 Oct 15;287 ( Pt 2)(Pt 2):481-5. doi: 10.1042/bj2870481.
The guanidinium chloride (GdmCl) denaturation of RNAase A, lysozyme and metmyoglobin was investigated at several pH values by using absorbance measurements at 287, 300 and 409 nm respectively. From these measurements the free-energy change on denaturation, delta Gapp., was calculated, assuming a two-state mechanism, and values of delta Gapp. at zero concentration of the denaturant were measured. For each protein all delta Gapp. values were adjusted to pH 7.00 by using the appropriate relationship between delta Gapp. and pH. Dependence of the adjusted delta Gapp. value on GdmCl concentration increases for metmyoglobin and decreases for the other two proteins as the denaturant concentration decreases. It has been shown that these are expected results if the presence of the acid-denatured state during the GdmCl denaturation of proteins is considered.
分别通过在287、300和409nm处测量吸光度，研究了在几个pH值下胍基氯化物（GdmCl）对核糖核酸酶A、溶菌酶和高铁肌红蛋白的变性作用。根据这些测量结果，假设为两态机制，计算了变性时的自由能变化ΔGapp.，并测量了变性剂浓度为零时的ΔGapp.值。对于每种蛋白质，通过使用ΔGapp.与pH之间的适当关系，将所有ΔGapp.值调整到pH 7.00。随着变性剂浓度降低，调整后的ΔGapp.值对GdmCl浓度的依赖性对于高铁肌红蛋白增加，而对于其他两种蛋白质则降低。结果表明，如果考虑到蛋白质在GdmCl变性过程中酸变性状态的存在，这些都是预期的结果。
