We study the mechanisms used by metalloenzymes to activate molecular oxygen. The specific enzymes we study fall into two broad classes. Some catalyze incorporation one or both atoms of oxygen from dioxygen into their organic substrates (methane monooxygenase, aromatic ring cleaving dioxygenases, or cis-diol forming Rieske dioxygenases). The second class create an in situ reagent from the activate oxygen for biosynthetic purposes without oxygen incorporation (isopenicillin N synthase, fosfomycin synthase, ACC oxidase). We utilize a variety of techniques including EPR spectroscopy, transient kinetics, crystallography, and diagnostic substrate reactions. One of our main goals is to discover the intermediates in the chemical reaction cycle of oxygen activating enzymes. These efforts have led to the discovery of intermediates in each of the enzyme classes listed above, most recently culminating in the solution of the crystal structures of the key intermediates in the extradiol aromatic ring cleaving dioxygenase class.
