title: Charge transfer in polypeptides: effect of secondary structures on charge-transfer integral and site energies.
abstract: 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, alpha-helix, 3(10)-helix, and antiparallel beta-sheet by varying the dihedral angles omega, varphi, and psi along the Calpha-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.
authors.affiliation: Department of Physics, Bharathiar University, Coimbatore, India-641 046.
authors.forename: N
authors.initials: N
authors.lastname: Santhanamoorthi
authors.forename: P
authors.initials: P
authors.lastname: Kolandaivel
authors.forename: K
authors.initials: K
authors.lastname: Senthilkumar
mesh_terms: D004583:Electrons; D005998:Glycine / Q000737:chemistry; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary
chemical_list: D010455:Peptides; D005998:Glycine