EXAFS spectroscopic evidence for an Fe=O unit in the Fe(IV) intermediate observed during oxygen activation by taurine:alpha-ketoglutarate dioxygenase

The Fe(II)- and alpha-ketoglutarate-dependent dioxygenases catalyze hydroxylation reactions of considerable biomedical and environmental significance. Recently, the first oxidized iron intermediate in the reaction of a member of this family, taurine:alpha-ketoglutarate dioxygenase (TauD), was detected and shown to be a high-spin Fe(IV) complex. In this study we have used X-ray absorption spectroscopy to demonstrate the presence of a short (1.62 A) interaction between the iron and one of its ligands in the Fe(IV) intermediate but not in the Fe(II) starting complex. The detection of this interaction strongly corroborates the hypothesis that the intermediate contains an Fe=O structural motif.