Abstract The impacts of pH, temperature, ionic strength and stirring speed on the assembly of ovotransferrin (OVT) into amyloid fibrils were analyzed by using thioflavin T fluorescence and atomic force microscopy. Optimum OVT nanofibrillation condition was achieved at pH 2, 90 °C, an ionic strength of 150 mM and a stirring speed of 300 rpm. Apart from rigid and long amyloid fibrils, flexible and short amyloid fibrils were also detected under the optimal condition. Morphological changes observed by atomic force microscopy as a function of time demonstrated that short OVT amyloid fibrils (with contour length below 800 nm) were generated upon heating for 1 h, and long OVT amyloid fibrils (with contour length above 800 nm) appeared after 6 h heating. In terms of structural characteristics, circular dichroism study revealed that internal structures of OVT amyloid fibrils could be stacked β-sheet. Analysis of fibril periodicity indicated that OVT amyloid fibrils might consist of 2 or 4 multi-stranded filaments. With the aid of ANS (1-anilino-8-naphthalensulfonate) fluorescence probe, it was found that OVT amyloid fibrils had lower surface hydrophobicity than untreated OVT. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay showed that OVT amyloid fibrils had no in vitro cytotoxicity, implying great application potential in food. This work will advance our understanding of amyloid fibrils derived from iron-bound proteins.

中文翻译：

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铁结合的卵转铁蛋白淀粉样原纤维的组装

摘要 采用硫代黄素T荧光和原子力显微镜分析pH、温度、离子强度和搅拌速度对卵转铁蛋白(OVT)组装成淀粉样原纤维的影响。在 pH 2、90 °C、150 mM 离子强度和 300 rpm 搅拌速度下实现了最佳的 OVT 纳米原纤化条件。除了刚性和长淀粉样原纤维外，在最佳条件下还检测到柔性和短淀粉样原纤维。原子力显微镜观察到的随时间变化的形态学变化表明，加热 1 h 后产生短的 OVT 淀粉样原纤维（轮廓长度低于 800 nm），加热 6 小时后出现长的 OVT 淀粉样原纤维（轮廓长度高于 800 nm）。加热。在结构特点上，圆二色性研究表明，OVT 淀粉样蛋白原纤维的内部结构可以堆叠 β-折叠。原纤维周期性分析表明，OVT 淀粉样原纤维可能由 2 或 4 条多链细丝组成。借助ANS（1-anilino-8-naphthalensulfonate）荧光探针，发现OVT淀粉样原纤维比未经处理的OVT具有更低的表面疏水性。MTT（3-（4,5-二甲基噻唑-2-基）-2,5-二苯基溴化四唑）测定表明OVT淀粉样原纤维在体外没有细胞毒性，在食品中具有很大的应用潜力。这项工作将促进我们对源自铁结合蛋白的淀粉样蛋白原纤维的理解。借助ANS（1-anilino-8-naphthalensulfonate）荧光探针，发现OVT淀粉样原纤维比未经处理的OVT具有更低的表面疏水性。MTT（3-（4,5-二甲基噻唑-2-基）-2,5-二苯基溴化四唑）测定表明OVT淀粉样原纤维在体外没有细胞毒性，在食品中具有很大的应用潜力。这项工作将促进我们对源自铁结合蛋白的淀粉样蛋白原纤维的理解。借助ANS（1-anilino-8-naphthalensulfonate）荧光探针，发现OVT淀粉样原纤维比未经处理的OVT具有更低的表面疏水性。MTT（3-（4,5-二甲基噻唑-2-基）-2,5-二苯基溴化四唑）测定表明OVT淀粉样原纤维在体外没有细胞毒性，在食品中具有很大的应用潜力。这项工作将促进我们对源自铁结合蛋白的淀粉样蛋白原纤维的理解。