Quantifying cation-π interactions in marine adhesive proteins using single-molecule force spectroscopy

Junsheng Zhang , Hai Lei , Meng Qin , Wei Wang , Yi Cao
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引用次数: 14

Abstract

In marine adhesives, cation-π interactions play an important role in their liquid-liquid phase separation process and underlying their strong interfacial bonding. However, it remains challenging to study the strength of cation-π interactions at the single-molecule level. Here, we engineer a recombinant chimeric polyprotein containing the mussel foot proteins-5 (MFP5) and a finger print domain GB1 to unambiguiously quantify the strength of cation-π interactions using atomic force microscopy (AFM)-based single-molecule force spectroscopy. Our results show that the formation of intermolecular cation-π interactions can be triggered at elevated salt concentrations, consistent with previous ensemble studies. Individual cation-π interaction ruptures at about 70 pN at a pulling speed of 1.6 μm s−1, comparable to the strength of other non-covalent interactions. The strength of cation-π interactions is weakly dependent on pH, which is in stark contrast with the hydrogen bonding and charge-charge interactions. Moreover, we find that the position of the cation-π bonds are formed randomly along the polyprotein chains. The propensity of forming long range cation-π interactions increases considerably when increasing the pH from 4 to 8, presumably due to the neutralization of the positive changes of MFP5. Our study directly quantifies the mechanical strength of cation-π bonds in the biological relavent settings and reveals key design parameters that may inspire the design of biomimetic strong underwater adhesives.

用单分子力谱定量海洋粘附蛋白中的阳离子-π相互作用
在海洋粘合剂中,阳离子-π相互作用在其液-液分离过程中起着重要作用,并奠定了其强界面键合的基础。然而,在单分子水平上研究阳离子-π相互作用的强度仍然具有挑战性。在这里,我们设计了一个含有贻贝足蛋白-5 (MFP5)和指纹结构域GB1的重组嵌合多蛋白,利用基于原子力显微镜(AFM)的单分子力谱,明确量化阳离子-π相互作用的强度。我们的研究结果表明,在高盐浓度下可以触发分子间阳离子-π相互作用的形成,与先前的系综研究一致。单个阳离子-π相互作用在约70 pN下以1.6 μm s−1的拉速破裂,与其他非共价相互作用的强度相当。阳离子-π相互作用的强度弱依赖于pH,这与氢键和电荷-电荷相互作用形成鲜明对比。此外,我们发现阳离子-π键的位置是沿多蛋白链随机形成的。当pH值从4增加到8时,形成远距离阳离子-π相互作用的倾向显著增加,可能是由于MFP5的正变化被中和。我们的研究直接量化了生物相关环境下阳离子-π键的机械强度,揭示了可能启发仿生强水下粘合剂设计的关键设计参数。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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CiteScore
6.70
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