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 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.
Santhanamoorthi
N
N
Department of Physics, Bharathiar University, Coimbatore, India-641 046.
Kolandaivel
P
P
Senthilkumar
K
K
D004583:Electrons; D005998:Glycine / Q000737:chemistry; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary
D010455:Peptides; D005998:Glycine