The adsorption of a corona has major impacts on the environmental fate of a released nanoparticle. While numerous techniques have been developed or adapted to determine corona composition, a detailed understanding of the forces that drive adsorption is lacking. Characterizing nanoparticle-corona complexes typically requires that the complex is isolated from the bulk medium prior to analysis, which can disrupt native interactions. To achieve a more detailed picture of protein-particle interactions, protein footprinting methods that were initially developed to investigate protein-protein interactions have been employed by us and others. Through the chemical labeling of solvent-exposed residues, molecular-level interactions can be obtained. Using a combination of protein footprinting and simulation, we previously showed preferential sites of interaction between cytochrome c (cyt c) and negatively charged gold nanoparticles, as well as evidence of protein deformation on the particle surface. Herein, we expand our investigation into a suite of proteins with differing propensity for deformation, as previously reported from acid exposure studies, and evaluate how matrix components affect protein binding orientation and/or deformation. We found that all three model proteins—cytochrome c, b-lactogloublin, and albumin—bound to nanoparticles through residues within flexible loop regions, that their secondary structure is unlikely to experience substantial deformation but may instead undergo localized conformational changes to enable additional residues to contact the particle surface, and that the protein complexes sometimes partially unfold (or deform) during the binding to the nanoparticle.

中文翻译：

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蛋白质-纳米颗粒相互作用的分子水平表征：取向、变形和基质效应


电晕的吸附对释放的纳米颗粒的环境归宿有重大影响。虽然已经开发或采用了许多技术来确定电晕组成，但缺乏对驱动吸附的力的详细理解。表征纳米颗粒-电晕复合物通常需要在分析之前将复合物与散装介质分离，这可能会破坏天然相互作用。为了更详细地了解蛋白质-颗粒相互作用，我们和其他人采用了最初为研究蛋白质-蛋白质相互作用而开发的蛋白质足迹方法。通过对溶剂暴露的残留物进行化学标记，可以获得分子水平的相互作用。使用蛋白质足迹和模拟的结合，我们之前显示了细胞色素 c （cyt c） 和带负电荷的金纳米颗粒之间相互作用的优先位点，以及颗粒表面蛋白质变形的证据。在此，我们将研究扩展到一组具有不同变形倾向的蛋白质，如之前从酸暴露研究中报道的那样，并评估基质成分如何影响蛋白质结合方向和/或变形。我们发现所有三种模型蛋白——细胞色素 c、b-乳腺素和白蛋白——都通过柔性环区域内的残基与纳米颗粒结合，它们的二级结构不太可能发生实质性变形，而是可能会发生局部构象变化，使额外的残基能够接触颗粒表面，并且蛋白质复合物有时会在与纳米颗粒结合期间部分展开（或变形）。