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Vacuum Ultraviolet Electronic Circular Dichroism Study of d-Glucose in Aqueous Solution.
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2020-01-21 , DOI: 10.1021/acs.jpca.9b09210 Koichi Matsuo 1 , Kunihiko Gekko 1
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2020-01-21 , DOI: 10.1021/acs.jpca.9b09210 Koichi Matsuo 1 , Kunihiko Gekko 1
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Vacuum ultraviolet (VUV) electronic circular dichroism (ECD) spectra of d-glucose, α-d-glucopyranose, and β-d-glucopyranose were measured in aqueous solution down to 163 nm using a synchrotron radiation VUV-ECD spectrophotometer and theoretically analyzed using molecular dynamics (MD) simulations with explicit water molecules and using time-dependent density functional theory (TDDFT). The theoretically calculated spectra reproduced the experimentally observed spectra well, revealing that VUV-ECD exhibited unique spectra depending on the α-anomer and β-anomer configurations of the hydroxyl group at C-1 and the three gauche (G) and trans (T) rotamer conformations (GT, GG, and TG) of the hydroxymethyl group at C-5. These unique spectra could be ascribed to differences in the patterns of intramolecular hydrogen bonds around the hydroxymethyl group at C-5 for the three rotamers and around the hydroxyl group at C-1 for the two anomers. The strengths of these intramolecular interactions increased as the degree of hydration around the corresponding chromophores decreased, suggesting that hydration is a key factor for stabilizing rotamer and anomer structures. The rotamerization and anomerization mechanisms are further discussed in terms of differences in the intramolecular interactions and the degree of hydration among the rotamer and anomer structures. The findings demonstrate that VUV-ECD spectroscopy is a useful tool for characterizing the equilibrium structures of monosaccharides.
中文翻译：
水溶液中d-葡萄糖的真空紫外电子圆二色性研究。
使用同步辐射VUV-ECD分光光度计在低至163 nm的水溶液中测量d-葡萄糖，α-d-吡喃葡萄糖和β-d-吡喃葡萄糖的真空紫外（VUV）电子圆二色性（ECD）光谱，并通过理论分析使用使用明确的水分子并使用时间依赖的密度泛函理论（TDDFT）进行分子动力学（MD）模拟。理论计算的光谱很好地重现了实验观察到的光谱，表明VUV-ECD表现出独特的光谱，这取决于C-1处的羟基的α-端基和β-端基构型以及三个gauche（G）和trans（T） C-5上的羟甲基的异构体构象（GT，GG和TG）。这些独特的光谱可以归因于三个旋转异构体在C-5处羟甲基周围和在C-1的两个异构体周围分子内氢键的模式差异。这些分子内相互作用的强度随着相应发色团周围水合程度的降低而增加，这表明水合是稳定旋转异构体和异构体结构的关键因素。根据分子内相互作用的差异以及旋转异构体和异构体结构之间的水合度，进一步讨论了旋转异构化机理。这些发现表明，VUV-ECD光谱学是表征单糖平衡结构的有用工具。
更新日期：2020-01-22
中文翻译：
水溶液中d-葡萄糖的真空紫外电子圆二色性研究。
使用同步辐射VUV-ECD分光光度计在低至163 nm的水溶液中测量d-葡萄糖，α-d-吡喃葡萄糖和β-d-吡喃葡萄糖的真空紫外（VUV）电子圆二色性（ECD）光谱，并通过理论分析使用使用明确的水分子并使用时间依赖的密度泛函理论（TDDFT）进行分子动力学（MD）模拟。理论计算的光谱很好地重现了实验观察到的光谱，表明VUV-ECD表现出独特的光谱，这取决于C-1处的羟基的α-端基和β-端基构型以及三个gauche（G）和trans（T） C-5上的羟甲基的异构体构象（GT，GG和TG）。这些独特的光谱可以归因于三个旋转异构体在C-5处羟甲基周围和在C-1的两个异构体周围分子内氢键的模式差异。这些分子内相互作用的强度随着相应发色团周围水合程度的降低而增加，这表明水合是稳定旋转异构体和异构体结构的关键因素。根据分子内相互作用的差异以及旋转异构体和异构体结构之间的水合度，进一步讨论了旋转异构化机理。这些发现表明，VUV-ECD光谱学是表征单糖平衡结构的有用工具。
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