9316565 Cramer The objective of the project is to obtain deeper insight into physical mechanisms of the charge transfer processes in biological membranes, in particular electron transfer in membrane-bound cytochromes and polar amino acid translocation across membranes. Physico-chemical experimental and theoretical studies of spectra, electrochemistry, and kinetics of model proteins and heme complexes would be combined with biochemical, biophysical crystallographic, and molecular biological analysis of the structure-function of photosynthetic electron transport proteins (cytochromes) and ion translocation of a bacterial ion channel (colicin). The problems whose understanding will be advanced as a result of these studies are as follows: the specific features of the dielectric reorganization of proteins and their surroundings in biological charge transfer processes; the mechanism of electron transfer in cytochromes including effects of electrostatic fields on the heme redox potentials, inner-sphere reorganization, reorganization of dielectric environment (membrane core, lipid heads), and electronic coupling via alpha-helices; mechanism of docking and electron transfer in the cytochrome f-plastocyanin system; the physical basis of the "cis-positive rule," describing orientation of intramembrane proteins; mechanism of trans-membrane channel formation by colicin and related toxin-like molecules. %%% The object of the project is to obtain a better understanding of the mechanism by which electrical charge is transferred or prevented from being transferred in the membranes that border and contain biological materials. The processes of charge movement in membranes are closely related to the mechanisms of cellular energy storage that take place in these membranes, and of the translocation of proteins across membranes that is associated with in the assembly of cellular structures and of the membranes themselves. ***
