Ab initio-based exciton model of amide I vibrations in peptides: definition, conformational dependence, and transferability

Gorbunov, Roman D., Kosov, Daniel, and Stock, Gerhard (2005) Ab initio-based exciton model of amide I vibrations in peptides: definition, conformational dependence, and transferability. Journal of Chemical Physics, 122 (22). 224904. pp. 1-12.

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Abstract

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 (ϕ,ψ) maps of the local-mode frequencies and couplings. Performing conformational averages of the (ϕ,ψ) maps with respect to the most important peptide conformational states in solution (α, β, P(Π), and C₅), 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.

Item ID: 26477
Item Type: Article (Research - C1)
ISSN: 1089-7690
Date Deposited: 21 Jun 2013 01:52
FoR Codes: 02 PHYSICAL SCIENCES > 0299 Other Physical Sciences > 029901 Biological Physics @ 50%
03 CHEMICAL SCIENCES > 0307 Theoretical and Computational Chemistry > 030701 Quantum Chemistry @ 50%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970102 Expanding Knowledge in the Physical Sciences @ 100%
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