Efficiency of charge transport in a polypeptide chain: The isolated system

We employ new single site molecular dynamics calculations to determine the time development of initial energization at an excitation site moving to a terminus. For this we find the efficiency of charge transport in an isolate d polypeptide. Based on our bifunctional model (Schlag, E. W.; Sheu, S.-Y.; Yang, D.-Y.; Settle, H. L.; Lin, S. H. Proc. Natl. Acad. Sci. U.S.A. 2000, 97, 1068), the charge transport along a polypeptide chain involves essenti al large amplitude chain motions and can be depicted as a virtual particle moving inside the bottom of a Ramachandran plot. The polypeptide is locally excited at a specific residue (or local heating), from which the energy is propagated. The motion of the virtual particle approaches a ballistic beha vior. Energy conservation is observed, which ensures, at long distance, mov ement of the charge and energy and hence provides a model for chemical reac tion at a distance. The high efficiency of charge transport is preserved do wn the chain in agreement with the experiment. Peptides thus represent a ne w unique class of molecular systems with near ideal conduction in the isola ted state-the task remains to define a suitable environment to maintain thi s high conductance.