Ab initio-based exciton model of amide I vibrations in peptides: Definition, conformational dependence, and transferability
Ab initio-based exciton model of amide I vibrations in peptides: Definition, conformational dependence, and transferability
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DOI：
10.1063/1.1898215
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发表时间：
2005-06-08
影响因子：
4.4
通讯作者：
Stock, G
中科院分区：
文献类型：
--
作者：
Gorbunov, RD;Kosov, DS;Stock, G
讨论了多肽中酰胺I振动的激子模型的从头算参数化的各个方面。采用“甘氨酸二肽”(Ac-Gly-NHCH3)作为描述两个多肽单元之间振动相互作用的简单积木模型，进行了全面的量子化学计算，考察了理论水平、局部坐标的选择和定域方法的影响和重要性。当进行完全几何优化(获得正确的频率所必需的)时，溶剂连续模型描述对于获得平面ConH多肽单元是重要的。为了研究酰胺I振动的构象依赖关系，我们计算了局域模式频率和耦合的(Phi，psi)图。对溶液中最重要的多肽构象状态(α、β、P-II和C-5)进行了(Phi，psi)图的构象平均，讨论了这些可测量与多肽的相应构象之间的关系。最后，我们考察了这些图谱对具有亲水和疏水侧链的二肽以及带有带电端基的三肽的可转移性。
Various aspects of the ab initio-based parametrization of an exciton model of amide I vibrations in peptides are discussed. Adopting "glycine dipeptide" (Ac-Gly-NHCH3) as a simple building-block model that describes the vibrational interaction between two peptide units, we perform comprehensive quantum-chemical calculations to investigate the effect and importance of the level of theory, the choice of local coordinates, and the localization method. A solvent continuum model description turns out important to obtain planar CONH peptide units when a full geometry optimization (which is necessary to obtain the correct frequencies) is performed. To study the conformational dependence of the amide I vibrations, we calculate (phi,psi) maps of the local-mode frequencies and couplings. Performing conformational averages of the (phi,psi) maps with respect to the most important peptide conformational states in solution (alpha, beta, P-II, and C-5), we discuss the relation between these measurable quantities and the corresponding conformation of the peptide. Finally, the transferability of these maps to dipeptides with hydrophilic and hydrophobic side chains as well as to tripeptides with charged end groups is investigated.