Partial hydrolysis of whey-based α-lactalbumin (α-La) with Bacillus licheniformis protease (BLP) induces the formation of nanotubular structures in the presence of calcium ions by a self-assembly process. α-La nanotubes (α-LaNTs) exist in the form of regular hollow strands with well-defined average dimensions. The growth of nanotubes induces the formation of stiff transparent protein gels due to the well-arranged networks that the strands can form; these gels can be used for entrapment, transportation, and target delivery of bioactive agents in the industry. High purity of α-La (free of other whey protein fractions) is desirable for nanotube formation; however, pure proteins are very expensive and not practically obtained for industrial applications. Thus, the purpose of this research was to construct α-LaNTs from an α-La preparation with lower purity and to study the gelation phenomena triggered by the self-assembled nanotubes. Some structural features of nanotube gels and their active agent-binding abilities were also investigated. A lower amount of α-LaNTs was observed when low purity α-La was used for nanotube formation. Nanotube growth induced gel formation and higher gel stiffness was obtained when compared to α-La hydrolysates. α-La was denatured after hydrolysis and self-assembly, and remarkable changes were observed in the α-helix and β-sheet domains of α-La structure. Increased intensity in Amide I and II regions indicated potential locations for binding of active agents to α-LaNTs. Whey-based α-La without much purification can be used to produce nanotubular gels and these gels can be considered carrying matrices for active agents in various industrial applications.

中文翻译：

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自组装α-乳清蛋白纳米管凝胶的结构和结合能力

地衣芽孢杆菌对乳清基 α-乳清蛋白 (α-La) 的部分水解蛋白酶 (BLP) 在钙离子存在下通过自组装过程诱导纳米管结构的形成。α-La 纳米管 (α-LaNTs) 以规则的空心链形式存在，具有明确的平均尺寸。由于链可以形成排列良好的网络，纳米管的生长诱导形成坚硬的透明蛋白质凝胶；这些凝胶可用于工业中生物活性剂的包埋、运输和靶向递送。高纯度的 α-La（不含其他乳清蛋白成分）对于纳米管的形成是可取的；然而，纯蛋白质非常昂贵，实际上无法用于工业应用。因此，本研究的目的是从纯度较低的 α-La 制剂中构建 α-LaNTs，并研究自组装纳米管引发的凝胶化现象。还研究了纳米管凝胶的一些结构特征及其活性剂结合能力。当使用低纯度 α-La 形成纳米管时，观察到较低量的 α-LaNT。与 α-La 水解产物相比，纳米管生长诱导凝胶形成和更高的凝胶刚度。α-La在水解和自组装后发生变性，α-La结构的α-螺旋和β-折叠结构域发生了显着变化。酰胺 I 和 II 区域的强度增加表明活性剂与 α-LaNT 结合的潜在位置。