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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Computational Vibrational Spectroscopy of HDO in Osmolyte-Water Solutions
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Computational Vibrational Spectroscopy of HDO in Osmolyte-Water Solutions

机译：渗透液-水溶液中HDO的计算振动光谱

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摘要

The IR absorption and time-resolved IR spectroscopy of the OD stretch mode of HDO in water was successfully used to study osmolyte effects on water H-bonding network. Protecting osmolytes such as sorbitol and trimethylglycine (TMG) make the vibrational OD stretch band red-shifted, whereas urea affects the OD band marginally. Furthermore, we recently showed that, even though sorbitol and TMG cause a slow-down of HDO rotation in their aqueous solutions, urea does not induce any change in the rotational relaxation of HDO in aqueous urea solutions even at high concentrations. To clarify the underlying osmolyte effects on water H-bonding structure and dynamics, we performed molecular dynamics (MD) simulations of a variety of aqueous osmolyte solutions. Using the vibrational solvatochromism model for the OD stretch mode and taking into account the vibrational non-Condon and polarization effects on the OD transition dipole moment, we then calculated the IR absorption spectra and rotational anisotropy decay of the OD stretch mode of HDO for the sake of direct comparisons with our experimental results. The simulation results on the OD stretch IR absorption spectra and the rotational relaxation rate of HDO in osmolyte solutions are found to be in quantitative agreement with experimental data, which confirms the validity of the MD simulation and vibrational solvatochromism approaches. As a result, it becomes clear that the protecting osmolytes like sorbitol and TMG significantly modulate water H-bonding network structure, while urea perturbs water structure little. We anticipate that the computational approach discussed here will serve as an interpretive method with atomic-level chemical accuracy of current linear and nonlinear time-resolved IR spectroscopy of structure and dynamics of water near the surfaces of membranes and proteins under crowded environments.
机译：HDO在水中的OD拉伸模式的红外吸收和时间分辨红外光谱已成功用于研究渗透液对水氢键网络的影响。保护性渗透剂（例如山梨糖醇和三甲基甘氨酸（TMG））使振动OD拉伸带发生红移，而尿素对OD带的影响很小。此外，我们最近表明，即使山梨糖醇和TMG导致其水溶液中HDO旋转减慢，即使在高浓度下，尿素也不会引起HDO在尿素水溶液中旋转弛豫的任何变化。为了弄清渗透剂对水氢键结构和动力学的潜在影响，我们对各种渗透剂水溶液进行了分子动力学（MD）模拟。使用OD拉伸模式的振动溶剂变色模型，并考虑到振动的非孔顿和极化效应对OD跃迁偶极矩的影响，因此，我们计算了HDO OD拉伸模式的红外吸收光谱和旋转各向异性衰减与我们的实验结果直接比较。发现渗透压溶液中OD拉伸IR吸收光谱和HDO的旋转弛豫速率的模拟结果与实验数据定量吻合，证实了MD模拟和振动溶剂变色方法的有效性。结果，很明显，保护性渗透物如山梨糖醇和TMG显着地调节了水的H键网络结构，而尿素对水的结构影响很小。我们期望这里讨论的计算方法将作为具有线性和非线性时间分辨红外光谱的原子级化学准确性的解释方法，在拥挤的环境下，膜和蛋白质表面附近水的结构和动力学具有线性和非线性时间分辨红外光谱。

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