Design of an Electrostatic Frequency Map for the NH Stretch of the Protein Backbone and Application to Chiral Sum Frequency Generation Spectroscopy
Design of an Electrostatic Frequency Map for the NH Stretch of the Protein Backbone and Application to Chiral Sum Frequency Generation Spectroscopy
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蛋白质主链 NH 拉伸静电频率图的设计及其在手性和频发生光谱中的应用
DOI：
10.1021/acs.jpcb.3c00217
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Hammes-Schiffer, Sharon
中科院分区：
文献类型：
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作者：
Konstantinovsky, Daniel;Perets, Ethan A.;Santiago, Ty;Olesen, Kristian;Wang, Zhijie;Soudackov, Alexander V.;Yan, Elsa C.Y.;Hammes-Schiffer, Sharon
我们开发了蛋白质主链振动 NH 拉伸（酰胺 A）的静电图，重点关注振动手性和频率发生光谱（手性 SFG）。手性 SFG 已被用于利用 NH 拉伸表征界面处的蛋白质二级结构，并利用 OH 拉伸研究蛋白质周围的手性水超结构。由于 NH 伸缩和 OH 伸缩在光谱上重叠，因此光谱的解释变得很复杂。尽管 Skinner 及其同事开发的水 OH 静电图之前已用于计算蛋白质周围水结构的手性 SFG 响应，但直接响应生物复杂性的蛋白质 NH 图尚未开发出来。在这里，我们开发了这样一个图，将局部电场与振动频率和跃迁偶极子联系起来。我们将该图谱应用于两个蛋白质系统，并与实验取得了比我们之前的研究更好的一致性。我们表明，NH 和 OH 振动之间的耦合对于线形至关重要，这为手性 SFG 光谱的解释提供了信息，并且手性 NH 拉伸响应对结构的微小差异很敏感。这项工作增加了 NH 拉伸在生物分子光谱中的实用性。
We develop an electrostatic map for the vibrational NH stretch (amide A) of the protein backbone with a focus on vibrational chiral sum frequency generation spectroscopy (chiral SFG). Chiral SFG has been used to characterize protein secondary structure at interfaces using the NH stretch and to investigate chiral water superstructures around proteins using the OH stretch. Interpretation of spectra has been complicated because the NH stretch and OH stretch overlap spectrally. Although an electrostatic map for water OH developed by Skinner and co-workers was used previously to calculate the chiral SFG response of water structures around proteins, a map for protein NH that is directly responsive to biological complexity has yet to be developed. Here, we develop such a map, linking the local electric field to vibrational frequencies and transition dipoles. We apply the map to two protein systems and achieve much better agreement with experiment than was possible in our previous studies. We show that couplings between NH and OH vibrations are crucial to the line shape, which informs the interpretation of chiral SFG spectra, and that the chiral NH stretch response is sensitive to small differences in structure. This work increases the utility of the NH stretch in biomolecular spectroscopy.