EFFECT OF SALT CONCENTRATION ON THE PK(A) OF ACIDIC RESIDUES IN LYSOZYME
EFFECT OF SALT CONCENTRATION ON THE PK(A) OF ACIDIC RESIDUES IN LYSOZYME
复制标题
DOI：
10.1093/jb/118.5.946
复制
发表时间：
1995-11-01
影响因子：
2.7
通讯作者：
IMOTO, T
中科院分区：
文献类型：
--
作者：
ABE, Y;UEDA, T;IMOTO, T
通过比较野生型和突变型溶菌酶的稳定性对pH的依赖关系，确定了鸡溶菌酶中酸性残基的pK(A)值。在比较野生型和突变型溶菌酶的稳定性时，它们在pH滴定曲线上的差异可以表示为一个单一酸性残基质子化的两态过程。结果表明，Aune和Tanford的蛋白质变性理论[Aune，K.C.和Tanford，C.(1969)BioChemical 8,4579-4585]适用于蛋白质在溶液中的稳定性。另一方面，用二维核磁共振方法测定了低盐浓度(5 MM)和高盐浓度(400 MM)下酸性残基的pK(A)值。Fire发现，在高盐条件下，从稳定性的pH依赖性得到的pK(A)值与从核磁共振实验得到的pK(A)值是剂量的。此外，通过比较高盐和低盐浓度下的pK(A)值，我们可以评估两种静电相互作用(盐桥和电荷-螺旋偶极相互作用)对盐浓度的依赖性。
We determined the pK(a) values of acidic residues in hen lysozyme by comparing the pH dependency of stability between wild type and mutant lysozymes in which a negative charge is eliminated. In the comparison of the stability between wild type and a mutant lysozyme, the difference in pH titration curve between them could be expressed as a two-state process involving protonation of a single acidic residue. The results strongly indicated that the Aune and Tanford theory of protein denaturation [Aune, K.C. and Tanford, C. (1969) Biochemistry 8, 4579-4585] is applicable to protein stability in solution, On the other hand, the pK(a) values of acidic residues in the presence of low (5 mM) or high (400 mM) salt concentration were determined by means of two-dimensional NMR. Fire found that the pK(a) values obtained hom the pH dependency of stability were dose to those from the NMR experiment under the high salt condition. Moreover, by comparing pK(a) values at high salt and low salt concentrations, we could evaluate the dependency of two electrostatic interactions (salt bridge and charge-helix dipole interaction) on salt concentration.