Spider dragline silk is well recognized due to its excellent mechanical properties. Dragline silk protein mainly consists of two proteins, namely, major ampullate spidroin 1 (MaSp1) and major ampullate spidroin 2 (MaSp2). The MaSp N-terminal domain (NTD) conformation displays a strong dependence on ion and pH gradients, which is crucial for the self-assembly behavior of spider silk. In the spider major ampullate gland, where the pH is neutral and concentration of NaCl is high, the NTD forms a monomer. In contrast, within the spinning duct, where pH becomes more acidic (to pH ~ 5) and the concentration of salt is low, NTD forms a dimer in antiparallel orientation. In this study, we report near-complete backbone and side chain chemical shift assignment of the monomeric form of NTD of MaSp2 from Nephila clavipes at pH 7 in the presence of 300 mM NaCl. Our NMR data demonstrate that secondary structure of monomeric form of NTD MaSp2 consists of five helix regions.

中文翻译：

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Nephila clavipes 大壶腹蛛丝 2 的单体形式的 N 末端结构域的单体形式的几乎完整的 1H、13C 和 15N 化学位移分配。

蜘蛛拉索丝因其优异的机械性能而广为人知。牵引丝蛋白主要由两种蛋白质组成，即大壶腹蛛丝蛋白 1 (MaSp1) 和大壶腹蛛丝蛋白 2 (MaSp2)。MaSp N 端结构域 (NTD) 构象显示出对离子和 pH 梯度的强烈依赖性，这对蜘蛛丝的自组装行为至关重要。在蜘蛛大壶腹腺中，pH 为中性且 NaCl 浓度高，NTD 形成单体。相比之下，在纺丝管内，pH 值变得更加酸性（至 pH 值 ~ 5）并且盐的浓度较低，NTD 形成反平行取向的二聚体。在这项研究中，我们报告了来自Nephila clavipes的 MaSp2 单体形式的 NTD 的近乎完整的主链和侧链化学位移分配在 300 mM NaCl 存在下，pH 7。我们的 NMR 数据表明 NTD MaSp2 单体形式的二级结构由五个螺旋区域组成。