Charge Transfer in Polypeptides:  Effect of Secondary Structures on Charge-Transfer Integral and Site Energies

We have theoretically studied the charge transfer in glycine polypeptide using quantum mechanical models based on a tight-binding Hamiltonian approach. The charge-transfer integrals and site energies involved in the transport of positive charge through the peptide bond in glycine polypeptide have be...

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Veröffentlicht in:The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2006-10, Vol.110 (40), p.11551-11556
Hauptverfasser: Santhanamoorthi, N, Kolandaivel, P, Senthilkumar, K
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Sprache:eng
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Zusammenfassung:We have theoretically studied the charge transfer in glycine polypeptide using quantum mechanical models based on a tight-binding Hamiltonian approach. The charge-transfer integrals and site energies involved in the transport of positive charge through the peptide bond in glycine polypeptide have been calculated. The charge-transfer integrals and site energies have been calculated directly from the matrix elements of the Kohn−Sham Hamiltonian defined in terms of the molecular orbitals of the individual fragments of the glycine polypeptide. In addition to this, we have calculated the rate of charge transfer between a neighboring amino acid subgroup through the Marcus rate equation. These calculations have been performed for the different secondary structures of the glycine model peptide such as linear, α-helix, 310-helix, and antiparallel β-sheet by varying the dihedral angles ω, φ, and ψ along the C α-carbon of amino acid subgroup. Present theoretical results confirm that the charge transfer through the peptide bond is strongly affected by the conformations of the oligopeptide.
ISSN:1089-5639
1520-5215
DOI:10.1021/jp063069n