The effect of hydrogen-bonding on flavin’s infrared absorption spectrum
The effect of hydrogen-bonding on flavin’s infrared absorption spectrum
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氢键对黄素红外吸收光谱的影响
DOI：
10.1016/j.saa.2021.120110
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Gozem, Samer
中科院分区：
文献类型：
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作者：
Kabir, Mohammad Pabel;Orozco-Gonzalez, Yoelvis;Hastings, Gary;Gozem, Samer
簇和连续溶剂化计算模型模拟的氢键相互作用的影响，光黄素的振动模式。在1450-1800 cm− 1的诊断范围内，计算光谱与实验傅里叶变换红外（FTIR）光谱进行了比较，发现了黄素异咯嗪环的强烈的ν C= C，ν C= N，ν C2 = O和ν C4 = O伸缩模。计算结果表明，ν C= C和ν C= N模的频率对分子间相互作用相对不敏感，而ν C2 = O和ν C4 = O模对直接氢键相互作用敏感（对ν C2 = O也是间接氢键相互作用）.虽然黄素是中性的，但没有漫射函数的基组提供了不正确的相对频率和强度。6-31+ G* 基组被认为是足够的，这个系统，并有有限的好处，考虑更大的基组。计算的振动模式频率同意实验确定的频率在溶液中使用时，集群模型与多个水分子。另一方面，相对FTIR谱带强度的精确模拟需要考虑长程静电效应的连续（或可能的量子力学/分子力学）模型。最后，在CA处的实验峰值。1624 cm− 1通常被分配给ν C 2= O振动伸缩模式，具有复杂的形状，表明有多个潜在的贡献。计算结果表明，C6-C7伸缩振动和C2 = O伸缩振动都对该带有贡献.
Cluster and continuum solvation computational models are employed to model the effect of hydrogen bonding interactions on the vibrational modes of lumiflavin. Calculated spectra were compared to experimental Fourier-transform infrared (FTIR) spectra in the diagnostic 1450–1800 cm− 1 range, where intense ν C= C, ν C= N, ν C 2= O, and ν C 4= O stretching modes of flavin’s isoalloxazine ring are found. Local mode analysis is used to describe the strength of hydrogen-bonding in cluster models. The computations indicate that ν C= C and ν C= N mode frequencies are relatively insensitive to intermolecular interactions while the ν C 2= O and ν C 4= O modes are sensitive to direct (and also indirect for ν C 2= O) hydrogen-bonding interactions. Although flavin is neutral, basis sets without the diffuse functions provide incorrect relative frequencies and intensities. The 6-31+ G* basis set is found to be adequate for this system, and there is limited benefit to considering larger basis sets. Calculated vibrational mode frequencies agree with experimentally determined frequencies in solution when cluster models with multiple water molecules are used. Accurate simulation of relative FTIR band intensities, on the other hand, requires a continuum (or possibly quantum mechanical/molecular mechanical) model that accounts for long-range electrostatic effects. Finally, an experimental peak at ca. 1624 cm− 1 that is typically assigned to the ν C 2= O vibrational stretching mode has a complicated shape that suggests multiple underlying contributions. Our calculations show that this band has contributions from both the C 6–C 7 and C 2= O stretching vibrations.