Tuning the Self-Assembly of Short Peptides via Sequence Variations

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• 作者：Yurong Zhao ; Jiqian Wang ; Li Deng ; Peng Zhou ; Shengjie Wang ; Yanting Wang ; Hai Xu ; Jian R. Lu
• 刊名：Langmuir
• 出版年：2013
• 出版时间：November 5, 2013
• 年：2013
• 卷：29
• 期：44
• 页码：13457-13464
• 全文大小：416K
• 年卷期：v.29,no.44(November 5, 2013)
• ISSN：1520-5827

文摘

Peptide self-assembly is of direct relevance to protein science and bionanotechnology, but the underlying mechanism is still poorly understood. Here, we demonstrate the distinct roles of the noncovalent interactions and their impact on nanostructural templating using carefully designed hexapeptides, I₂K₂I₂, I₄K₂, and KI₄K. These simple variations in sequence led to drastic changes in final self-assembled structures. 尾-sheet hydrogen bonding was found to favor the formation of one-dimensional nanostructures, such as nanofibrils from I₄K₂ and nanotubes from KI₄K, but the lack of evident 尾-sheet hydrogen bonding in the case of I₂K₂I₂ led to no nanostructure formed. The lateral stacking and twisting of the 尾-sheets were well-linked to the hydrophobic and electrostatic interactions between amino acid side chains and their interplay. For I₄K₂, the electrostatic repulsion acted to reduce the hydrophobic attraction between 尾-sheets, leading to their limited lateral stacking and more twisting, and final fibrillar structures; in contrast, the repulsive force had little influence in the case of KI₄K, resulting in wide ribbons that eventually developed into nanotubes. The fibrillar and tubular features were demonstrated by a combination of cryogenic transmission electron microscopy (cryo-TEM), negative-stain transmission electron microscopy (TEM), and small-angle neutron scattering (SANS). SANS also provided structural information at shorter scale lengths. All atom molecular dynamics (MD) simulations were used to suggest possible molecular arrangements within the 尾-sheets at the very early stage of self-assembly.