Bio-Interface and Environmental Engineering Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam.
J Biomol Struct Dyn. 2021 Oct;39(17):6415-6423. doi: 10.1080/07391102.2020.1798814. Epub 2020 Jul 27.
Protein aggregation is induced by various environmental or external factors and associated with various neurodegenerative diseases. Among various external factors, shear stress is inevitable for both and applications of proteins. In this study, Aβ (1-40) peptide, a derivative of the amyloid precursor protein, was subjected to constant (300, 500, 700 s) and varying (ramp) shear in a parallel plate geometry to explore the implications of shear in terms of macro (viscosity) and micro (secondary structure, morphology) characteristics. Aβ (1-40) solution followed a shear thickening flow behaviour with performance index value '' of 2.12. The fibrillation process resulting from the shear force was evaluated in terms of dissipation energy, which was found to exceed the free energy of unfolding. This resulted in the formation of β-sheet rich structures, which were confirmed by CD and FTIR analyses and enhanced Th-T fluorescence. The apparent rate of aggregation () was found to increase with the shear rate, and inversely related to the solution viscosity. The maximum value was 0.21 ± 0.3 min at 700 s. The molecular weights of aggregates were determined using gel filtration, which were proportionally related to the solution viscosity. The average molecular weights were estimated to be 70, 62 and 52 KDa for samples sheared at 300, 500 and 700 s, respectively. The present study has deciphered the interplay of viscosity, a fluid property, with the aggregation process and its corresponding change in the secondary structures of the peptide. These findings provide useful insights for understanding various proteopathies under shear force.Communicated by Ramaswamy H. Sarma.
蛋白质聚集是由各种环境或外部因素诱导的，并与各种神经退行性疾病有关。在各种外部因素中，切应力是蛋白质 和 应用中不可避免的。在这项研究中，Aβ（1-40）肽，一种淀粉样前体蛋白的衍生物，在平行板几何形状中受到恒定（300、500、700 s）和变化（斜坡）剪切的作用，以探索剪切在宏观（粘度）和微观（二级结构、形态）特性方面的影响。Aβ（1-40）溶液表现出剪切增稠流动行为，性能指数值“”为 2.12。用耗散能评估了由剪切力引起的纤化过程，发现其超过了展开自由能。这导致形成富含 β-折叠结构的结构，这通过 CD 和 FTIR 分析以及增强的 Th-T 荧光得到证实。发现聚集的表观速率（）随剪切速率的增加而增加，与溶液粘度成反比。在 700 s 时，最大 值为 0.21±0.3 min。使用凝胶过滤法测定聚集体的分子量，其与溶液粘度成正比。对于在 300、500 和 700 s 下剪切的样品，平均分子量估计分别为 70、62 和 52 kDa。本研究揭示了粘度（一种流体性质）与聚集过程及其相应的肽二级结构变化之间的相互作用。这些发现为理解剪切力下的各种蛋白病提供了有用的见解。由 Ramaswamy H. Sarma 传达。
