Enzyme oxidizes single-handedly

Enzymes that catalyze oxidation reactions typically rely on metal or organic cofactors to activate molecular oxygen. A handful of unusual oxygenase enzymes activate O₂ single-handedly, however, and Boston College chemists now think they know how such enzymes manage this feat. Steven D. Bruner and colleagues present a 2.75-Å X-ray structure of DpgC, a cofactor-free dioxygenase that catalyzes a key step in the biosynthesis of an amino acid required to assemble the antibiotic vancomycin (Nature 2007, 447, 342). DpgC incorporates both oxygen atoms of a single O₂ molecule into its substrate and releases coenzyme A (CoA), yielding a precursor to the necessary amino acid, as shown. In the crystal structure, Bruner's team discerned what they believe to be O₂ tucked into a hydrophobic corner of the enzyme's active site near the substrate oxidation site. On the basis of the structure, the researchers suggest an unusual mechanism in which the substrate provides the reducing power to activate O₂ to perform the oxidation.