氧化型大肠杆菌硫氧还蛋白的稳定性及其对26位天冬氨酸残基质子化的依赖性。

Stability of oxidized Escherichia coli thioredoxin and its dependence on protonation of the aspartic acid residue in the 26 position.

作者信息

Ladbury J E, Wynn R, Hellinga H W, Sturtevant J M

机构信息

Department of Chemistry, Yale University, New Haven, Connecticut 06511.

出版信息

Biochemistry. 1993 Jul 27;32(29):7526-30. doi: 10.1021/bi00080a026.

DOI:10.1021/bi00080a026

PMID:8393344

Abstract

The effects of pH in the range 6.0-8.0 on the thermodynamics of the reversible thermal unfolding of Escherichia coli thioredoxin in the oxidized state have been determined over a range of concentrations using differential scanning calorimetry. The thermal denaturation indicated an inverse temperature dependence on concentration. The data were shown to fit a model based on dimerization of both the native and denatured states of the protein. The degree of dimerization of both states was found to be pH dependent. The previously described importance of protonation of the anomalously titrating aspartic acid 26 residue [Langsetmo, K., Fuchs, J., & Woodward, C. (1991) Biochemistry 30 ,7603-7609] was apparently verified by the agreement between the experimentally determined delta delta Gzerod and the calculated delta delta GzeroH in the pH range 7.0-8.0.

摘要

利用差示扫描量热法，在一系列浓度范围内测定了pH值在6.0 - 8.0之间对氧化态大肠杆菌硫氧还蛋白可逆热解折叠热力学的影响。热变性表明浓度与温度呈反比关系。数据显示符合基于蛋白质天然态和变性态二聚化的模型。发现两种状态的二聚化程度都依赖于pH值。先前描述的异常滴定的天冬氨酸26残基质子化的重要性[Langsetmo, K., Fuchs, J., & Woodward, C. (1991) Biochemistry 30, 7603 - 7609]，显然通过在pH值7.0 - 8.0范围内实验测定的ΔΔG°和计算的ΔΔG°H之间的一致性得到了验证。