Pan Kang, Zhong Qixin
Department of Food Science and Technology, University of Tennessee in Knoxville, USA.
Soft Matter. 2015 Aug 7;11(29):5898-904. doi: 10.1039/c5sm01037c.
Amyloid-like fibrils are studied because of their significance in understanding pathogenesis and creating functional materials. Amyloid-like fibrils have been studied by heating globular proteins at acidic conditions. In the present study, intrinsically disordered α-, β-, and κ-caseins were studied to form amyloid-like fibrils at pH 2.0 and 90 °C. No fibrils were observed for α-caseins, and acid hydrolysis was found to be the rate-limiting step of fibrillation of β- and κ-caseins. An increase of β-sheet structure was observed after fibrillation. Nanomechanic analysis of long amyloid-like fibrils using peak-force quantitative nanomechanical atomic force microscopy showed the lowest and highest Young's modulus for β-casein (2.35 ± 0.29 GPa) and κ-casein (4.14 ± 0.66 GPa), respectively. The dispersion with β-casein fibrils had a viscosity more than 10 and 5 times higher than those of κ-casein and β-lactoglobulin, respectively, at 0.1 s(-1) at comparable concentrations. The current findings may assist not only the understanding of amyloid fibril formation but also the development of novel functional materials from disordered proteins.
类淀粉样纤维因其在理解发病机制和制造功能材料方面的重要性而受到研究。类淀粉样纤维已通过在酸性条件下加热球状蛋白进行了研究。在本研究中，对内在无序的α-、β-和κ-酪蛋白在pH 2.0和90°C下形成类淀粉样纤维进行了研究。未观察到α-酪蛋白形成纤维，且发现酸水解是β-和κ-酪蛋白纤维化的限速步骤。纤维化后观察到β-折叠结构增加。使用峰值力定量纳米力学原子力显微镜对长类淀粉样纤维进行纳米力学分析表明，β-酪蛋白（2.35±0.29 GPa）和κ-酪蛋白（4.14±0.66 GPa）的杨氏模量分别最低和最高。在可比浓度下，在0.1 s(-1)时，β-酪蛋白纤维的分散体粘度分别比κ-酪蛋白和β-乳球蛋白的粘度高10倍和5倍以上。目前的研究结果不仅有助于理解淀粉样纤维的形成，还有助于从无序蛋白质开发新型功能材料。
