KINETICS AND MECHANISM STUDIES IN BIOMIMETIC CHEMISTRY - METALLOENZYME MODEL SYSTEMS

To understand the biological transport and utilization of dioxygen at the level of mechanistic chemistry it has been necessary to synthesize small molecules (active site sections) which carry out the binding or catalytic function. We have prepared iron porphyrin compounds which mimic the dioxygen binding to myoglobin and the oxidations catalyzed by peroxidases and related enzymes. Using a combination of structural and environmental perturbations and millisecond to subpicosecond laser photolysis methods of following bimolecular or cage reactions we have established many of the factors which control dioxygen binding to heme proteins as well as details of cage processes in ligand binding to small molecules. Additionally, effective catalysts for biomimetic oxidations have been developed and studied by kinetic methods. Studies of the effects of catalyst, oxidant and substrate structure and of environment on the rates of these catalytic processes have allowed mechanisms of epoxidation, hydroxylation and biomimetic suicide labelling to be determined.