Advances in studying bioinorganic reaction mechanisms: isotopic probes of activated oxygen intermediates in metalloenzymes

Metalloenzymes catalyze reactions of molecular oxygen and its reduced forms through the controlled formation of metal-bound, activated oxygen intermediates. These intermediates have been a challenge to characterize and new experimental approaches capable of relating structure to reactivity under physiologically relevant conditions are needed. The application of a competitive isotope fractionation technique has enabled changes in O–O bonding to be probed during enzyme-catalyzed reactions. The derived isotope effects provide insights into the reaction mechanisms of O 2 and O 2 −, which probably could not have been obtained using more conventional methods.