Electrostatic origin of the cooperative effect on the C=O bond lengths and the amide I vibrational frequencies of the N-methylacetamide oligomers
Electrostatic origin of the cooperative effect on the C=O bond lengths and the amide I vibrational frequencies of the N-methylacetamide oligomers
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DOI：
10.1016/j.molstruc.2004.10.082
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发表时间：
2005-02-14
影响因子：
3.8
通讯作者：
Torii, H
中科院分区：
文献类型：
--
作者：
Torii, H
分析了n -甲基乙酰胺低聚物分子间电场作用，探讨了协同作用对酰胺I模式振动子空间C = O键长和对角线力常数影响的原因。本文认为，产生协同效应的电场的增强有以下三个重要因素：(1)分子间距离的变化（由氢键长度的变化引起）；(2)直接作用于远分子间的电场的存在；(3)远分子间介入分子的极化。结果表明，第三个因素可以用偶极感应偶极机制合理地解释。在此基础上提出了正确表述静电效应对多肽和蛋白质结构和振动模式的要求。(C) 2004 Elsevier B.V.版权所有
the electric,fields operating among the molecules in the oligomers of N-methylacetamide are analyzed to see the reasons for the cooperative effect on the C = O bond lengths and the diagonal force constants in the vibrational subspace of the amide I mode. It is suggested that the following three factors are important for the enhancement of the electric field that gives rise to the cooperative effect: (1) the changes in the intermolecular distances (arising from the changes in the hydrogen-bond lengths): (2) the existence of the electric field directly operating between distant molecules, and (3) the polarization of the intervening molecule(s) between distant molecules. It is shown that the third factor is reasonably explained by the dipole-induced dipole mechanism. Some requirements for the correct representation of the electrostatic effects on the structures and the vibrational modes of polypeptides and proteins are proposed on the basis of this result. (C) 2004 Elsevier B.V. All rights reserved.