Chiral Sum Frequency Generation Spectroscopy for Characterizing Protein Secondary Structures at Interfaces
Chiral Sum Frequency Generation Spectroscopy for Characterizing Protein Secondary Structures at Interfaces
复制标题
DOI：
10.1021/ja201575e
复制
发表时间：
2011-06-01
影响因子：
15
通讯作者：
Yan, Elsa C. Y.
中科院分区：
文献类型：
--
作者：
Fu, Li;Liu, Jian;Yan, Elsa C. Y.
蛋白质二级结构的原位和实时表征在生物和生物工程科学中是重要的，但仍然具有技术挑战性。在这项研究中，我们使用手性和频产生（SFG）光谱建立了一套振动光学标记，用于表征蛋白质二级结构的界面。我们发现，在手性SFG光谱中可以检测到N-H沿着α-螺旋的肽骨架沿着伸展。我们进一步观察到，N-H伸缩与肽酰胺I的手性振动特征对于界面处的α-螺旋、β-折叠和无规卷曲是独特的。使用这些手性振动签名，我们研究了人胰岛淀粉样多肽（hIAPP）的聚集，这与II型糖尿病有关。我们在原位和真实的时间观察到hIAPP从无规卷曲到α-螺旋，然后在与脂质-水界面相互作用时发生β-折叠的错误折叠。我们的研究结果表明，手性SFG光谱是一个强大的工具，以遵循蛋白质构象的变化在接口和识别界面蛋白质二级结构，逃避常规技术。
In situ and real-time characterization of protein secondary structures at interfaces is important in biological and bioengineering sciences, yet remains technically challenging. In this study, we used chiral sum frequency generation (SFG) spectroscopy to establish a set of vibrational optical markers for characterizing protein secondary structures at interfaces. We discovered that the N-H stretches along the peptide backbones of alpha-helices can be detected in chiral SFG spectra. We further observed that the chiral vibrational signatures of the N-H stretch together with the peptide amide I are unique to alpha-helix, beta-sheet, and random coil at interfaces. Using these chiral vibrational signatures, we studied the aggregation of human islet amyloid polypeptide (hIAPP), which is implicated in type II diabetes. We observed in situ and in real time the misfolding of hIAPP from random coils to alpha-helices and then beta-sheets upon interaction with a lipid water interface. Our findings show that chiral SFG spectroscopy is a powerful tool to follow changes in protein conformations at interfaces and identify interfacial protein secondary structures that elude conventional techniques.