Native-like β-structure in a Trifluoroethanol-induced Partially Folded State of the All-β-sheet Protein Tendamistat
Native-like β-structure in a Trifluoroethanol-induced Partially Folded State of the All-β-sheet Protein Tendamistat
复制标题
三氟乙醇诱导的全β片层蛋白Tendamistat的部分折叠状态下的天然β结构
DOI：
--
复制
发表时间：
1996
期刊：
影响因子：
--
通讯作者：
T. Kiefhaber
中科院分区：
文献类型：
--
作者：
N. Schönbrunner;J. Wey;J. Engels;H. Georg;T. Kiefhaber
研究了三氟乙醇（TFE）对全β-片层蛋白tenamistat结构的影响。在低浓度下，TFE 会导致天然三级结构的协同损失，导致部分折叠状态。在从天然状态到 TFE 诱导状态的转变过程中，特定侧链相互作用的丧失通过芳香区 CD 带的消失、一维 1H NMR 谱中化学位移分散的减少以及部分折叠状态的广泛的、不合作的热展开转变来证明。与未折叠状态相比，TFE 状态下的 NMR 谱带线宽增加，表明存在多种快速相互转换的构象。对 TFE 状态酰胺蛋白的氢交换研究表明，在与天然状态相同的位置存在确定的氢键，但稳定性大大降低。这表明存在大部分天然β-折叠结构。这些结果得到了傅里叶变换红外测量的支持，该测量显示 TFE 状态和天然状态下的 β 结构数量几乎相同。远紫外 CD 光谱表明，添加 TFE 后会诱导产生一些 α-螺旋结构，该结构似乎主要位于与天然状态下的环或随机结构相对应的区域，并且似乎代表具有优选主链角度的波动构象，而不是稳定的氢键 α-螺旋。这些结果表明，当β-折叠中发生稳定的非局部相互作用时，可以在没有特定侧链相互作用的情况下形成。天然长程相互作用子集的存在和稳定非天然相互作用的缺乏表明，观察到的部分折叠状态可能代表腾达司他分级折叠途径的早期中间体。
The effect of trifluoroethanol (TFE) on the structure of the all-β-sheet protein tendamistat was investigated. At low concentrations TFE induces cooperative loss of the native tertiary structure leading to a partially folded state. The loss of specific side-chain interactions in the transition from the native state to the TFE-induced state is demonstrated by the disappearance of the CD bands in the aromatic region, a reduced chemical shift dispersion in the one-dimensional1H NMR spectrum and a broad, uncooperative thermal unfolding transition of the partially folded state. An increased line-width of the NMR bands in the TFE state compared with the unfolded state suggests the presence of multiple, rapidly interconverting con- formations. Hydrogen-exchange studies of amide proteins in the TFE state reveal the existence of defined hydrogen bonds at the same locations as in the native state, but with largely reduced stability. This suggests the presence of most of the native β-sheet structure. These results are supported by Fourier transformed IR measurements, which show nearly the same amount of β-structure in the TFE state and in the native state. Far UV CD spectroscopy suggests the induction of some α-helical structure upon addition of TFE, which appears to be located mainly in regions corresponding to loops or random structure in the native state and which seems to represent fluctuating conformations with preferred backbone angles rather than stable, hydrogen-bonded α-helices. These results show that stable non-local interactions, as they occur in β-sheets, can form in the absence of specific side-chain interactions. The presence of a subset of the native long-range interactions and the absence of stable non-native interactions suggests that the observed partially folded state might represent an early intermediate on a hierarchial folding pathway of tendamistat.