ABSTRACT
Natural membranes are characterized by high selectivity, specificity, and control processes whose mechanisms of operation can be reduced to molecular levels. Many of these processes involve self-assembly of macromolecules such as lipids, proteins, and DNA. In 1941 Szent-Gyorgyi suggested that proteins and other materials may possess some of the solid-state electronic properties known to occur in amorphous materials and organic polymers (1). Since then, electronic processes in living systems have been extensively studied, especially in connection with coupled redox reactions in mitochondria, energy transfer and conversion in chloroplasts, and sensory transduction in visual systerns. Bilayer lipid membrane-based structures responsible for carrying out the aforementioned processes may be the transducers. Whether we can construct similar membrane devices by emulating natural systems remains to be seen, but the approach is a viable one. The purpose of this chapter is to review data and concepts involving the study of electronic properties of both natural membranes and experimental lipid bilayer systems such as planar bilayer lipid membranes (BLMs) and spherical liposomes. Although the emphasis will be on the BLM systems, it is appropriate to deal first with natural membranes and then proceed to their models because the study of BLMs originated from attempts to better understand processes in 182natural membranes. Jointly studying natural membranes and artificial lipid bilayers, leads to both a better understanding of natural membranes, and the possibility of constructing bilayer systems capable of performing basic biological functions such as photosynthesis (2–5).
