γ-II晶状体蛋白的尿素变性与稳定性

Urea unfolding and stability of gamma-II crystallin.

作者信息

Shosheva A C, Christova P K, Spassov V Z, Atanasov B P

机构信息

Central Laboratory of Biophysics, Bulgarian Academy of Sciences, Sofia.

出版信息

J Photochem Photobiol B. 1993 Dec;21(2-3):183-9. doi: 10.1016/1011-1344(93)80181-8.

DOI:10.1016/1011-1344(93)80181-8

PMID:8301414

Abstract

The conformational stability of gamma-II crystallin at pH 7.0 was estimated by studying its urea denaturation at isothermal conditions. The conformational states were monitored by far UV-CD and fluorescence measurements. Gamma-II crystallin shows sigmoidal order-disorder transition curves by both methods. The presence of more than one intermediate was confirmed but at neutral pH. The experiment results were critically analyzed in terms of both linear extrapolation and Tanford's models. The Gibbs free energy of unfolding delta G u,H2O = -36 kcal mol-1 was obtained. This value corresponds to the high conformational stability of the protein predicted qualitatively by its crystal structure.

摘要

通过研究γ-II晶状体蛋白在等温条件下的尿素变性，估算了其在pH 7.0时的构象稳定性。通过远紫外圆二色光谱（far UV-CD）和荧光测量监测构象状态。两种方法均显示γ-II晶状体蛋白呈现S形的有序-无序转变曲线。证实了存在不止一种中间体，但处于中性pH条件下。根据线性外推法和坦福德模型对实验结果进行了严格分析。得到了去折叠的吉布斯自由能ΔGu,H2O = -36 kcal mol-1。该值与根据蛋白质晶体结构定性预测的高构象稳定性相对应。