Dr. Harry B. Gray and Dr. John H. Richards, Chemistry Department, California Institute of Technology, are supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program of the Chemistry Division to develop methods and materials for studying the intermediates in the oxygen-activation chemistry of single heme proteins. A series of kinetic studies which focus on the critical O-O bond cleavage reactions will be carried out. Photochemical methods will be developed for rapidly injecting electrons into the dioxygen coordinated to iron of a heme group. According to current theories is the step which initiates O-O bond cleavage in these enzymes. By study of the resulting excited states information will be obtained on reaction intermediates and the details of the O-O bond cleavage mechanism. Systems to be investigated include heme-cavity-modified forms of myoglobin, horseradish peroxidase, and mutants of yeast cytochrome c. Oxygen is a powerful and readily available oxidant, yet man-made catalysts that effectively utilize oxygen are rare. The best examples of oxygen activation and utilization are found in biochemical systems. Iron containing enzymes are responsible for a large portion of biochemical oxygen activation. Nonetheless, the exact way in which these iron containing biomolecules are able to activate oxygen is unclear. This project is designed to probe the mechanism of the critical oxygen-oxygen bond cleave process which must lie at the heart of the process. An understanding of how the biological systems operate may permit new ways of directly utilizing oxygen in a variety of laboratory and industrial processes.
