OvoA from ovothiol biosynthesis is a bifunction enzyme: thiol oxygenase and sulfoxide synthase activities.

Mononuclear non-heme iron enzymes are a large class of enzymes catalyzing a wide-range of reactions. In this work, we report that a non-heme iron enzyme in , OvoA has two different activities, as a thiol oxygenase and a sulfoxide synthase. When cysteine is presented as the only substrate, OvoA is a thiol oxygenase. In the presence of both histidine and cysteine as substrates, OvoA catalyzes the oxidative coupling between histidine and cysteine (a sulfoxide synthase). Additionally, we demonstrate that both substrates and the active site iron's secondary coordination shell residues exert exquisite control over the dual activities of OvoA (sulfoxide synthase thiol oxygenase activities). OvoA is an excellent system for future detailed mechanistic investigation on how metal ligands and secondary coordination shell residues fine-tune the iron-center electronic properties to achieve different reactivities.