Polaronic electron transfer in beta-sheet protein models

We consider electron transfer (ET) along beta -sheet forms of proteins. The secondary structure of the beta -sheet proteins is modelled by a two-dimen sional oscillator network whose constituents represent peptide units. Coval ent and hydrogen bonds between the peptide units are represented by point-p oint interaction potentials. Intrapeptide vibrational degrees of freedom ar e taken into account by means of harmonic oscillators while the electronic motion is described within the framework of a tight-binding system. We cons truct polarons as stationary localized solution states utilizing a non-line ar map approach. The polaron state represents a self-trapped electron in co njunction with its intrapeptide deformation field and the static deformatio n of the protein scaffolding. Furthermore, in the dynamical study we focus attention on the initiation of polaron motion, utilizing its pinning modes. We show that both the covalent and the hydrogen channel provide a path for coherent ET in beta -sheet proteins. It is demonstrated that the interplay of the vibrations of the protein scaffolding and the electron dynamics pro motes long-lived localized excitation patterns travelling coherently along the lattice of peptide units.