Grziwa A, Maack S, Pühler G, Wiegand G, Baumeister W, Jaenicke R
Max-Planck-Institut für Biochemie, Martinsried, Germany.
Eur J Biochem. 1994 Aug 1;223(3):1061-7. doi: 10.1111/j.1432-1033.1994.tb19084.x.
The proteasome from the thermoacidophilic archaeon Thermoplasma acidophilum in its native state represents a 20S particle with significant secondary structure (approximately 35% alpha helix) of its subunits. Electron microscopy, ultracentrifugal and spectral analysis demonstrate that at pH of less than 3 dissociation to partially denatured subunits occurs. Upon dialysis against near neutral pH buffers, at low protein concentration, reconstitution occurs, leading to the restoration of up to 90% of the native fluorescence signal. The recovery of activity depends on several parameters, including the buffer system, the pH used to dissociate the complex, and the duration of exposure to low pH. High concentrations of Ca2+ and Mg2+ cause partial dissociation of the Thermoplasma proteasome, yielding distinct subcomplexes. Neither the completely nor the partially dissociated complexes have proteolytic activity, indicating that function is linked to fully assembled proteasomes.
嗜热嗜酸古菌嗜热栖热菌的蛋白酶体在其天然状态下是一个20S颗粒，其亚基具有显著的二级结构（约35%为α螺旋）。电子显微镜、超速离心和光谱分析表明，在pH值小于3时，会发生解离，形成部分变性的亚基。在低蛋白浓度下，用接近中性pH值的缓冲液透析时，会发生重组，导致高达90%的天然荧光信号得以恢复。活性的恢复取决于几个参数，包括缓冲系统、用于解离复合物的pH值以及暴露于低pH值的持续时间。高浓度的Ca2+和Mg2+会导致嗜热栖热菌蛋白酶体部分解离，产生不同的亚复合物。完全解离或部分解离的复合物均无蛋白水解活性，这表明功能与完全组装的蛋白酶体相关。
