CHARACTERIZATION OF A PARTIALLY DENATURED STATE OF A PROTEIN BY 2-DIMENSIONAL NMR - REDUCTION OF THE HYDROPHOBIC INTERACTIONS IN UBIQUITIN
CHARACTERIZATION OF A PARTIALLY DENATURED STATE OF A PROTEIN BY 2-DIMENSIONAL NMR - REDUCTION OF THE HYDROPHOBIC INTERACTIONS IN UBIQUITIN
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DOI：
10.1021/bi00226a020
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发表时间：
1991-03-26
期刊：
影响因子：
2.9
通讯作者：
WOOLFSON, DN
中科院分区：
文献类型：
--
作者：
HARDING, MM;WILLIAMS, DH;WOOLFSON, DN
在298 K、pH 2.0、60%甲醇/40%水溶液中形成稳定的、部分结构化状态的泛素，即A-状态。 这种状态的结构的详细表征已通过2D NMR光谱进行。 分配缓慢交换酰胺共振保护从溶剂中的天然和A-状态表明，总的蛋白质结构重组尚未发生，A-状态包含一个子集的相互作用存在于天然状态（N-状态）。 邻位偶联常数和NOESY数据显示存在于天然蛋白质中的五链β折叠的前两条链和第三条β链的一部分。 A状态下β-折叠的疏水面被部分结构化的α-螺旋覆盖，暂时分配给残基24 - 34，其比N状态下的α-螺旋柔性大得多。 有证据表明这两个结构单元之间存在一些固定的侧链-侧链相互作用。 该蛋白质的富含转角的区域包含七个反向转角和一小段3（10）螺旋，似乎在A状态下没有结构化，并且接近无规卷曲。
A stable, partially structured state of ubiquitin, the A-state, is formed at pH 2.0 in 60% methanol/40% water at 298 K. Detailed characterization of the structure of this state has been carried out by 2D NMR spectroscopy. Assignment of slowly exchanging amide resonances protected from the solvent in the native and A-state shows that gross structural reorganization of the protein has not occurred and that the A-state contains a subset of the interactions present in the native state (N-state). Vicinal coupling constants and NOESY data show the presence of the first two strands of the five-strand beta-sheet that is present in the native protein and part of the third beta-strand. The hydrophobic face of the beta-sheet in the A-state is covered by a partially structured alpha-helix, tentatively assigned to residues 24-34, that is considerably more flexible than the alpha-helix in the N-state. There is evidence for some fixed side-chain-side-chain interactions between these two units of structure. The turn-rich area of the protein, which contains seven reverse turns and a short piece of 3(10) helix, does not appear to be structured in the A-state and is approaching random coil.