Identification of the response of protein N-H vibrations in vibrational sum-frequency generation spectroscopy of aqueous protein films
Identification of the response of protein N-H vibrations in vibrational sum-frequency generation spectroscopy of aqueous protein films
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DOI：
10.1039/c6cp08325k
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发表时间：
2017-05-07
影响因子：
3.3
通讯作者：
Bakker, H. J.
中科院分区：
文献类型：
--
作者：
Meister, K.;Paananen, A.;Bakker, H. J.
N-H拉伸振动是研究蛋白质结构和功能特性的重要探针，但由于它与水分子的O-H拉伸振动重叠，通常难以分析。在这项工作中，我们使用常规（VSFG）和外差检测振动和频率产生光谱（HD-VSDG）研究了疏水蛋白的N-H信号。疏水蛋白代表了一组表面活性蛋白，它们在水-空气界面形成高度有序的蛋白质膜，并产生显著的振动模式。我们发现，在常规的VSFG光谱中，随着pH值的改变，N-H特异性信号的形状和强度发生了显著的变化。这些变化很容易被误解为蛋白质的构象变化。通过HD-VSFG实验，我们证明了疏水蛋白薄膜的N-H响应随pH值的变化可以很好地解释为N-H响应与宽界面水O-H拉伸带的干扰。
The N-H stretching vibration is an important probe for investigating structural and functional properties of proteins but is often difficult to analyze as it overlaps with the O-H stretching vibration of water molecules. In this work we investigate the N-H signals of hydrophobins using conventional (VSFG) and heterodyne-detected vibrational sum-frequency generation spectroscopy (HD-VSDG). Hydrophobins represent a group of surface active proteins that form highly-ordered protein films at the water-air interface and that give rise to prominent vibrational modes. We find that in conventional VSFG spectra N-H specific signals show significant changes in shape and intensity upon altering the pH values. These changes can easily be misinterpreted for conformational changes of the protein. Using HD-VSFG experiments, we demonstrate, that for hydrophobin films the change of the N-H response with pH can be well explained from the interference of the N-H response with the broad interfacial water O-H stretch band.