Abstract In this study, valyl-methionine dipeptide (Val-Met), a breakdown product of protein digestion or protein catabolism,has been investigated both theoretically and experimentally. Four different valyl-methionine conformations were formed, using the geometric parameters of two asymmetric units of L-Valine and L-Methionine, taken from the literature and their optimized geometric parameters were obtained by DFT/B3LYP level of theory, using different basis sets. The vibrational spectral analysis for the obtained two energetically most stable conformations were carried out theoretically by using 6-311++G(d,p) basis set. Experimental vibrational spectra of the title molecule were compared with the calculated spectra and the vibrational modes were assigned on the basis of potential energy distributions (PED) analysis, performed using the MOLVIB program. Furthermore, molecular electrostatic potential map analysis was carried out and dipole moment of the compound was calculated. Conformation analysis is an important step in molecular modeling. The selection of suitable conformers for many flexible drug molecules, which can be present in many conformations by turning around single bonds, to adopt different conformations, can easily be overlooked. In this work a series of dipeptide with A and B forms of valine and methionine amino acids have been chosen as examples to demonstrate the importance of conformational analysis. Energy differences between conformations underline the importance of a detailed conformational analysis and should be taken into account when defining their activities. Results show that the formation of hydrogen bonds between N1 and H17 and between H17 and O25 in Valyl(B)-Methionine(B) dipeptide, affects the stability of the molecule. The molecular electrostatic potential of the title molecule has also been calculated which is a very useful property in prediction of molecular reactive behavior. In addition, in silico molecular docking studies were performed for the title molecule with DNA. The results indicated the ability of the Val-Met dipeptide to bind DNA.

中文翻译：

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Valyl-Methionine 二肽的振动光谱表征、量子化学和分子对接研究

摘要 本研究对缬氨酰甲硫氨酸二肽 (Val-Met) 作为蛋白质消化或蛋白质分解代谢的分解产物进行了理论和实验研究。使用L-缬氨酸和L-甲硫氨酸这两个不对称单元的几何参数，形成了四种不同的缬氨酰-甲硫氨酸构象，取自文献，并通过DFT/B3LYP理论水平，使用不同的基组获得优化的几何参数。通过使用6-311++G(d,p)基组，对获得的两种能量最稳定构象进行了理论上的振动光谱分析。将标题分子的实验振动光谱与计算光谱进行比较，并根据势能分布 (PED) 分析指定振动模式，使用 MOLVIB 程序执行。此外，进行分子静电势图分析并计算化合物的偶极矩。构象分析是分子建模的重要步骤。许多柔性药物分子的合适构象异构体的选择很容易被忽视，这些药物分子可以通过扭转单键以多种构象存在，采用不同的构象。在这项工作中，选择了一系列具有 A 和 B 形式的缬氨酸和甲硫氨酸的二肽作为示例，以证明构象分析的重要性。构象之间的能量差异强调了详细构象分析的重要性，在定义其活动时应予以考虑。结果表明，缬氨酰(B)-甲硫氨酸(B)二肽中N1和H17之间以及H17和O25之间形成的氢键影响分子的稳定性。还计算了标题分子的分子静电势，这是预测分子反应行为非常有用的特性。此外，对带有 DNA 的标题分子进行了计算机模拟分子对接研究。结果表明 Val-Met 二肽结合 DNA 的能力。