肌钙蛋白C N结构域的稳定性和折叠研究。关于中间体形成的证据。

Stability and folding studies of the N-domain of troponin C. Evidence for the formation of an intermediate.

作者信息

Ramos Carlos H I, Lima Milton V, Silva Silvia L F, Borin Paula F L, Régis Wiliam C B, Santoro Marcelo M

机构信息

Centro de Biologia Molecular Estrutural, Laboratório Nacional de Luz Síncrotron, CP 6192, Campinas SP, 13084-971, Brazil.

出版信息

Arch Biochem Biophys. 2004 Jul 15;427(2):135-42. doi: 10.1016/j.abb.2004.05.002.

DOI:10.1016/j.abb.2004.05.002

PMID:15196987

Abstract

We report here on the stability and folding of the 91 residue alpha-helical F29W N-terminal domain of chicken skeletal muscle troponin C (TnC(1-91)F29W), the thin filament calcium-binding component. Unfolding was monitored by differential scanning calorimetry, circular dichroism, and intrinsic fluorescence spectroscopy using urea, pH, and temperature as denaturants, in the absence and in the presence of calcium. The unfolding of TnC(1-91)F29W was reversible and did not follow a two-state transition, suggesting that an intermediate may be present during this reaction. Our results support the hypothesis that intermediates are likely to occur during the folding of small proteins and domains. The physiological significance of the presence of an intermediate in the folding pathway of troponin C is discussed.

摘要

我们在此报告鸡骨骼肌肌钙蛋白C（TnC(1 - 91)F29W）91个残基的α - 螺旋F29W N端结构域（细肌丝钙结合成分）的稳定性和折叠情况。在有无钙存在的情况下，分别使用尿素、pH值和温度作为变性剂，通过差示扫描量热法、圆二色光谱法和内源荧光光谱法监测其展开过程。TnC(1 - 91)F29W的展开是可逆的，且不遵循两态转变，这表明在此反应过程中可能存在一个中间体。我们的结果支持这样的假设，即在小蛋白质和结构域的折叠过程中可能会出现中间体。文中还讨论了肌钙蛋白C折叠途径中存在中间体的生理意义。