Ostrander Joshua S, Lomont Justin P, Rich Kacie L, Saraswat Vivek, Feingold Benjamin R, Petti Megan K, Birdsall Erin R, Arnold Michael S, Zanni Martin T
Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States.
Department of Materials Science and Engineering , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States.
J Phys Chem Lett. 2019 Jul 18;10(14):3836-3842. doi: 10.1021/acs.jpclett.9b01267. Epub 2019 Jun 27.
Immunosensors use antibodies to detect and quantify biomarkers of disease, though the sensors often lack structural information. We create a surface-sensitive two-dimensional infrared (2D IR) spectroscopic immunosensor for studying protein structures. We tether antibodies to a plasmonic surface, flow over a solution of amyloid proteins, and measure the 2D IR spectra. The 2D IR spectra provide a global assessment of antigen structure, and isotopically labeled proteins give residue-specific structural information. We report the 2D IR spectra of fibrils and monomers using a polyclonal antibody that targets human islet amyloid polypeptide (hIAPP). We observe two fibrillar polymorphs differing in their structure at the G24 residue, which supports the hypothesis that hIAPP polymorphs form from a common oligomeric intermediate. This work provides insight into the structure of hIAPP, establishes a new method for studying protein structures using 2D IR spectroscopy, and creates a spectroscopic immunoassay applicable for studying a wide range of biomarkers.
免疫传感器利用抗体来检测和量化疾病的生物标志物，不过这些传感器通常缺乏结构信息。我们创建了一种用于研究蛋白质结构的表面敏感型二维红外（2D IR）光谱免疫传感器。我们将抗体连接到等离子体表面，使其流过淀粉样蛋白溶液，并测量二维红外光谱。二维红外光谱提供了对抗原结构的整体评估，而同位素标记的蛋白质则给出了残基特异性的结构信息。我们使用针对人胰岛淀粉样多肽（hIAPP）的多克隆抗体报告了原纤维和单体的二维红外光谱。我们观察到两种原纤维多晶型物在G24残基处结构不同，这支持了hIAPP多晶型物由共同的寡聚中间体形成的假设。这项工作深入了解了hIAPP的结构，建立了一种使用二维红外光谱研究蛋白质结构的新方法，并创建了一种适用于研究广泛生物标志物的光谱免疫分析方法。
