Backbone dynamics and structural characterization of the partially folded A state of ubiquitin by H-1, C-13, and N-15 nuclear magnetic resonance spectroscopy
Backbone dynamics and structural characterization of the partially folded A state of ubiquitin by H-1, C-13, and N-15 nuclear magnetic resonance spectroscopy
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DOI：
10.1021/bi971538t
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发表时间：
1997-10-21
期刊：
影响因子：
2.9
通讯作者：
Ernst, RR
中科院分区：
文献类型：
--
作者：
Brutscher, B;Bruschweiler, R;Ernst, RR
采用全C-13， n -15标记的泛素，利用二维和三维核磁共振波谱（NMR）研究了pH为2的60%/40%甲醇/水混合物中泛素部分折叠A态的结构和动力学。完成了主链(CO)-C-13、C-13（α）、N-15和H-1(N)的分配。（CO）-C-13和C-13（α）化学位移和H-1-H-1核Overhauser增强（NOE）连接表明蛋白质的n端和c端有不同的行为。在A态的n端，包括反平行的β -片和中央α -螺旋，天然二级结构元素大部分是保守的。c端半部分具有丰富的天然形式-链特征，经历甲醇诱导过渡到具有一致的高螺旋结构倾向的动态状态。这种行为也反映在主干N-15弛豫数据中，表明存在三个松散耦合的二级结构段，与原始状态相比，内部迁移率增强。
Structure and dynamics of the partially folded A state of ubiquitin in a 60%/40% methanol/water mixture at pH 2 was studied by two-and three-dimensional nuclear magnetic resonance spectroscopy (NMR) using fully C-13,N-15-labeled ubiquitin. Complete backbone (CO)-C-13,C-13(alpha), N-15, and H-1(N) assignment was achieved. (CO)-C-13 and C-13(alpha) chemical shifts and H-1-H-1 nuclear Overhauser enhancement (NOE) connectivities indicate different behavior for the N-terminal and the C-terminal halves of the protein. In the N-terminal half of the A state, comprising the antiparallel beta-sheet and the central alpha-helix, the native secondary structural elements are largely conserved. The C-terminal half, which is in the native form rich in beta-strand character, undergoes a methanol-induced transition to a dynamic state with a uniformly high propensity for helical structure. This behavior is also reflected in backbone N-15 relaxation data, indicating the presence of three loosely coupled secondary structural segments with enhanced internal mobility as compared to the native state.