蛋白质G'的二级结构，一种稳定的分子。
The secondary structure of protein G', a robust molecule.
作者信息
Goward C R, Irons L I, Murphy J P, Atkinson T
机构信息
Division of Biotechnology, P.H.L.S. Centre for Applied Microbiology and Research, Porton Down, Salisbury, Wilts, U.K.
出版信息
Biochem J. 1991 Mar 1;274 ( Pt 2)(Pt 2):503-7. doi: 10.1042/bj2740503.
The secondary structure of recombinant streptococcal Protein G' was predicted and compared with spectropolarimetric data. The predicted secondary structure consisted of 37 +/- 4% alpha-helix and 30 +/- 5% beta-sheet, whereas the values obtained from c.d. data were 29 +/- 2% alpha-helix and 41 +/- 3% beta-sheet. An alpha-helix-beta-sheet/turn-alpha-helix motif is conjectured to comprise the Fc-binding unit. The c.d. spectra in the near u.v. and far u.v. show that the Protein G' molecule is stable to heating at 100 degrees C and to extremes of pH (pH 1.5 to 11.0). The protein retained biological activity at these extremes. The molecule uncoils above pH 11.5 in a time-dependent fashion. Unfolding of the molecule in guanidinium chloride was monitored by c.d. and fluorescence emission; 3 M-guanidinium chloride was required to unfold the protein by 50%. The protein was completely unfolded in 5.5 M-guanidinium chloride and fully refolded with restoration of activity after removal of guanidinium chloride.
对重组链球菌蛋白G'的二级结构进行了预测，并与圆二色光谱数据进行了比较。预测的二级结构由37±4%的α-螺旋和30±5%的β-折叠组成，而从圆二色光谱数据获得的值为29±2%的α-螺旋和41±3%的β-折叠。推测一个α-螺旋-β-折叠/转角-α-螺旋基序构成Fc结合单元。近紫外和远紫外的圆二色光谱表明，蛋白G'分子在100℃加热以及极端pH值（pH 1.5至11.0）条件下是稳定的。该蛋白在这些极端条件下仍保留生物活性。在pH 11.5以上，分子以时间依赖性方式解旋。通过圆二色光谱和荧光发射监测蛋白在氯化胍中的解折叠；需要3 M氯化胍才能使蛋白50%解折叠。蛋白在5.5 M氯化胍中完全解折叠，去除氯化胍后可完全重新折叠并恢复活性。
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