STELA Dairy Research Center, Institute of Nutraceuticals and Functional Foods, Université Laval, Quebec City, QC, Canada G1V0A6.
J Agric Food Chem. 2011 Jan 26;59(2):720-6. doi: 10.1021/jf103312t. Epub 2010 Dec 23.
The objective of the present work was to investigate the physicochemical conditions that trigger the self-assembly of peptide β-lg f1-8 and therefore lead to nanofibers and hydrogel formation. Nanostructures formed by self-assembly of peptide β-lg f1-8 in the pH range of 2.0-11.0 were studied by transmission electron microscopy (TEM). Hydrogel formation was studied as a function of pH and resulted in evidence of a link between hydrogel formation and the charge distribution carried by the peptide structure. Finally, circular dichroism (CD) spectroscopy was used to characterize the effects of peptide concentration (0.4-2.0 mg/mL), ionic strength (0-1 M NaCl), and temperature (20-80 °C) on the secondary structure of peptide β-lg f1-8. Hydrogels were obtained at peptide concentrations above 2.5 mg/mL. Peptide concentration and pH adjustment were shown to trigger self-assembly of β-lg f1-8, but increasing ionic strength had no effect. Heating to 80 °C induced a stronger CD signal intensity due to an increase in solubility of the peptide, whereas only slight changes in CD pattern were found upon cooling to 20 °C. Overall, results emphasize the role of particular molecular interactions in β-sheet self-assembly of peptide β-lg f1-8 and pH-dependent electrostatic interactions occurring between β-lg f1-8 units, which can explain its propensity to self-assembly.
本工作的目的是研究触发肽 β-lg f1-8 自组装并形成纳米纤维和水凝胶的理化条件。通过透射电子显微镜（TEM）研究了在 pH 值 2.0-11.0 范围内由肽 β-lg f1-8 自组装形成的纳米结构。研究了水凝胶形成作为 pH 的函数，并证明了水凝胶形成与肽结构所携带的电荷分布之间存在联系。最后，使用圆二色性（CD）光谱来表征肽浓度（0.4-2.0 mg/mL）、离子强度（0-1 M NaCl）和温度（20-80°C）对肽 β-lg f1-8 二级结构的影响。在肽浓度高于 2.5 mg/mL 时获得水凝胶。结果表明，肽浓度和 pH 调节会触发β-lg f1-8 的自组装，但增加离子强度没有影响。加热至 80°C 会由于肽的溶解度增加而导致 CD 信号强度增强，而冷却至 20°C 时仅发现 CD 图谱略有变化。总体而言，结果强调了特定分子相互作用在肽 β-lg f1-8 的β-折叠自组装中的作用以及β-lg f1-8 单元之间发生的 pH 依赖性静电相互作用，这可以解释其自组装的倾向。
