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首页> 外文期刊>The Journal of Chemical Physics >A new scheme for determining the intramolecular seven-membered ring N-H...O=C hydrogen-bonding energies of glycine and alanine peptides
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A new scheme for determining the intramolecular seven-membered ring N-H...O=C hydrogen-bonding energies of glycine and alanine peptides

机译：确定甘氨酸和丙氨酸肽分子内七元环N-H ... O = C氢键能的新方案

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In this paper a new scheme was proposed to calculate the intramolecular hydrogen-bonding energies in peptides and was applied to calculate the intramolecular seven-membered ring N-H...O=C hydrogen-bonding energies of the glycine and alanine peptides.The density-functional theory B3LYP/6-31G(d) and B3LYP/6-311G(d,p) methods and the second-order M011er-Plesset perturbation theory MP2/6-31G(d) method were used to calculate the optimal geometries and frequencies of glycine and alanine peptides and related structures.MP2/6-311 + +G(d,p),MP2/6-3ll + +G(3df,2p),and MP2/aug-cc-pVTZ methods were then used to evaluate the single-point energies.It was found that the B3LYP/6-31G(d),MP2/6-31G(d),and B3LYP/6 -311G(d,p) methods yield almost similar structural parameters for the conformers of the glycine and alanine dipeptides.MP2/aug-cc-pVTZ predicts that the intramolecular seven-membered ring N-H...O=C hydrogen-bonding strength has a value of 5.54 kcal/mol in glycine dipeptide and 5.73 and 5.19 kcal/mol in alanine dipeptides,while the steric repulsive interactions of the seven-membered ring conformers are 4.13 kcal/mol in glycine dipeptide and 6.62 and 3.71 kcal/mol in alanine dipeptides.It was also found that MP2/6-311 + +G(3df,2p) gives as accurate intramolecular N-H...O=C hydrogen-bonding energies and steric repulsive interactions as the much more costly MP2/aug-cc-pVTZ does.
机译：本文提出了一种计算肽中分子内氢键能的新方案，并将其用于计算甘氨酸和丙氨酸肽的分子内七元环NH ... O = C氢键能。使用功能理论B3LYP / 6-31G（d）和B3LYP / 6-311G（d，p）方法以及二阶M0​​11er-Plesset微扰理论MP2 / 6-31G（d）方法来计算最佳几何形状和频率然后使用MP2 / 6-311 + + G（d，p），MP2 / 6-3ll + + G（3df，2p）和MP2 / aug-cc-pVTZ方法分析甘氨酸和丙氨酸肽及其相关结构评估B3LYP / 6-31G（d），MP2 / 6-31G（d）和B3LYP / 6 -311G（d，p）方法得出的构象异构体结构参数几乎相似MP2 / aug-cc-pVTZ预测分子内七元环NH ... O = C氢键结合强度在甘氨酸二肽中为5.54 kcal / mol，在5.73和5.19 kcal中丙氨酸二肽中的/ mol，而七元环构象异构体的空间排斥相互作用在甘氨酸二肽中为4.13 kcal / mol，在丙氨酸二肽中为6.62和3.71 kcal / mol。还发现MP2 / 6-311 + + G （3df，2p）与更昂贵的MP2 / aug-cc-pVTZ所产生的分子内NH ... O = C氢键能和空间排斥相互作用一样准确。

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