Abstract The conformation of glutathione is of great significance for its biological function. In this study, the absorption spectra of reduced (GSH) and oxidized (GSSG) glutathione in the frequency range of 0.5–12.0 THz were obtained by air plasma terahertz time-domain spectroscopy (THz-TDS). The results demonstrated that GSH had rich characteristic absorption peaks in the THz region, while GSSG presented a monotonous absorption spectrum without obvious peaks. Combined with powder X-ray diffraction (PXRD), GSH had a certain crystal structure and GSSG was amorphous, suggesting that the THz spectroscopy was sensitive to the molecular structure and crystal form. The density functional theory (DFT) calculation based on the GSH crystal structure was performed to simulate the THz absorption spectrum and analyze the vibrational property. The result showed that GSH molecule could form rich inter- and intramolecular hydrogen bonds which helped to constrain flexible peptide. Lattice vibrations and hydrogen bonds of GSH could effectively resonate with THz waves. The different THz absorption peaks of GSH corresponded to different collective or local molecular vibrations which were closely related to the hydrogen bonding interactions. The study may help to deepen the understanding of GSH molecular conformation and weak interactions.

中文翻译：

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谷胱甘肽的宽带太赫兹光谱

摘要 谷胱甘肽的构象对其生物学功能具有重要意义。在这项研究中，通过空气等离子体太赫兹时域光谱 (THz-TDS) 获得了 0.5-12.0 THz 频率范围内还原型 (GSH) 和氧化型 (GSSG) 谷胱甘肽的吸收光谱。结果表明，GSH在太赫兹区域具有丰富的特征吸收峰，而GSSG则呈现单调的吸收光谱，没有明显的吸收峰。结合粉末X射线衍射（PXRD），GSH具有一定的晶体结构，GSSG为无定形，表明太赫兹光谱对分子结构和晶型敏感。进行基于GSH晶体结构的密度泛函理论（DFT）计算以模拟THz吸收光谱并分析振动特性。结果表明，GSH分子可以形成丰富的分子间和分子内氢键，有助于约束柔性肽。GSH的晶格振动和氢键可以有效地与太赫兹波共振。GSH 不同的太赫兹吸收峰对应于不同的集体或局部分子振动，这与氢键相互作用密切相关。该研究可能有助于加深对GSH分子构象和弱相互作用的理解。GSH 不同的太赫兹吸收峰对应于不同的集体或局部分子振动，这与氢键相互作用密切相关。该研究可能有助于加深对GSH分子构象和弱相互作用的理解。GSH 不同的太赫兹吸收峰对应于不同的集体或局部分子振动，这与氢键相互作用密切相关。该研究可能有助于加深对GSH分子构象和弱相互作用的理解。