Long-range electron transfer in peptides: Influence of peptide conformation and side chain separation upon electron transfer element

The geometries of neutral indole and phenol, as well as their cation radicals and anion radicals, have been optimized by using AM1 method. In the double-well potential constructions of the electron transfer (ET) between indole cation radical and neutral phenol, linear reaction coordinate approximation has been adopted, and the conductor-like screening model has been involked. Based on the indole-phenol double-well potential, the reaction heat and the inner reorganization energy of ET between tryptophan and tyrosine have been evaluated. AM1 method has been applied to obtain the geometries and the conformations of TrpH-(Pro)(n)-TyrOH (n = 0-3) model systems. ET matrix elements for the intramolecular ET in those model peptides have been estimated through the determination of the minimum of the energy splitting factor.