Yokoyama Kazushige, Ichiki Akane
Department of Chemistry, The State University of New York Geneseo College, Geneseo, NY, United States.
Colloids Surf A Physicochem Eng Asp. 2021 Apr 20;615:126275. doi: 10.1016/j.colsurfa.2021.126275. Epub 2021 Feb 4.
Gold nano-particles were coated with the spike protein (S protein) of SARS-CoV-2 and exposed to increasingly acidic conditions. Their responses were investigated by monitoring the surface plasmon resonance (SPR) band shift. As the external pH was gradually changed from neutral pH to pH ∼2 the peak of the SPR band showed a significant red-shift, with a sigmoidal feature implying the formation of the gold-protein aggregates. The coating of S protein changed the surface property of the gold enough to extract the coverage fraction of protein over nano particles, Θ, which did not exhibit clear nano-size dependence. The geometrical simulation to explain Θ showed the average axial length to be = 7. 25 nm and =8.00 nm when the S-protein was hypothesized as a prolate shape with spiking-out orientation. As the pH value externally hopped between pH∼3 and pH∼10, a behavior of reversible protein folding was observed for particles with diameters >30 nm. It was concluded that S protein adsorption conformation was impacted by the size (diameter, d) of a core nano-gold, where head-to-head dimerized S protein was estimated for d ≤ 80 nm and a in formation for d = 100 nm.
将新冠病毒（SARS-CoV-2）的刺突蛋白（S蛋白）包被在金纳米颗粒上，并使其暴露于酸性不断增强的环境中。通过监测表面等离子体共振（SPR）带的位移来研究其响应情况。随着外部pH值从中性逐渐变化至pH约为2，SPR带的峰值出现了显著的红移，呈现出S形特征，这意味着形成了金-蛋白聚集体。S蛋白的包被改变了金的表面性质，从而能够测定蛋白质在纳米颗粒上的覆盖分数Θ，该覆盖分数并未表现出明显的纳米尺寸依赖性。用于解释Θ的几何模拟表明，当假设S蛋白为具有突出取向的长形时，其平均轴向长度分别为 = 7.25 nm和 = 8.00 nm。当外部pH值在pH约为3和pH约为10之间跳跃时，观察到直径大于30 nm的颗粒出现了可逆蛋白质折叠行为。得出的结论是，S蛋白的吸附构象受核心纳米金尺寸（直径，d）的影响，其中对于d≤80 nm估计为头对头二聚化的S蛋白，而对于d = 100 nm则为形成 。
