D'Auria S, Moracci M, Febbraio F, Tanfani F, Nucci R, Rossi M
Istituto di Biochimica delle Proteine ed Enzimologia, Consiglio Nazionale delle Ricerche, Naples, Italy.
Biochimie. 1998 Nov;80(11):949-57. doi: 10.1016/s0300-9084(00)88892-6.
beta-Glycosidase from the extreme thermophilic archaeon Sulfolobus solfataricus is a thermostable tetrameric protein with a molecular mass of 240 kDa which is stable in the presence of detergents and has a maximal activity above 95 degrees C. An understanding of the structure-function relationship of the enzyme under different chemical-physical conditions is of fundamental importance for both theoretical and application purposes. In this paper we report the effect of basic pH values on the structural stability of this enzyme. The structure of the enzyme was studied at pH 10 and in the temperature range 25-97.5 degrees C using circular dichroism, Fourier-transform infrared and fluorescence spectroscopy. The spectroscopic data indicated that the enzyme stability was strongly affected by pH 10 suggesting that the destabilization of the protein structure is correlated with the perturbation of ionic interactions present in the native protein at neutral pHs. These experiments give support to the observation derived from the 3D-structure, that large ion pair networks on the surface stabilize Sulfolobus solfataricus beta-glycosidase.
来自极端嗜热古菌嗜热栖热菌的β-糖苷酶是一种热稳定的四聚体蛋白，分子量为240 kDa，在洗涤剂存在下稳定，在95摄氏度以上具有最大活性。了解该酶在不同化学物理条件下的结构-功能关系对于理论和应用目的都至关重要。在本文中，我们报告了碱性pH值对该酶结构稳定性的影响。使用圆二色性、傅里叶变换红外光谱和荧光光谱在pH 10以及25-97.5摄氏度的温度范围内研究了该酶的结构。光谱数据表明，pH 10对酶的稳定性有强烈影响，这表明蛋白质结构的不稳定与中性pH下天然蛋白质中存在的离子相互作用的扰动有关。这些实验支持了从三维结构得出的观察结果，即表面上的大离子对网络稳定了嗜热栖热菌β-糖苷酶。
