Photosynthesis, the process by which light energy is converted into chemical potential by plants, algae, and some forms of bacteria, is the basis for all life on earth. The primary photochemical event catalyzed by the absorption of light by these organisms involves a special protein complex called the reaction center (RC) in which an electron is transferred by bound cofactors across a biological membrane, and the resulting electrical potential is stabilized. Despite years of intense research into the structure and function of the RC, a fundamental understanding is still lacking regarding the molecular factors that control electron transfer in photosynthetic systems. Understanding the mechanism of how electron transfer operates in the RC is central to several agricultural issues including plant resistance to stress, herbicide activity, and oxygen production. The goal of this research is to employ our novel synthetic approaches formulating thin RC protein films in conjunction with advanced voltammetric techniques to reveal the electrochemical properties of the RC. We will apply these techniques to RC proteins prepared from several photosynthetic organisms. These methods will allow, for the first time, direct monitoring of electrical events in the RC protein. Characteristic electrochemical properties of the proteins and their associated cofactors, and the effect structural modifications have on these properties will be obtained and are keys to understanding how the RC protein achieves efficient electron transport across biological membranes.