Insight into the mechanism of an iron dioxygenase by resolution of steps following the FeIV=HO species.
Iron oxygenases generate elusive transient oxygen species to catalyze substrate oxygenation in a wide range of metabolic processes. Here we resolve the reaction sequence and structures of such intermediates for the archetypal non-heme Fe(II) and alpha-ketoglutarate-dependent dioxygenase TauD. Time-resolved Raman spectra of the initial species with (16)O(18)O oxygen unequivocally establish the Fe(IV) horizontal lineO structure. (1)H/(2)H substitution reveals direct interaction between the oxo group and the C1 proton of substrate taurine. Two new transient species were resolved following Fe(IV) horizontal lineO; one is assigned to the nu(FeO) mode of an Fe(III) horizontal line O(H) species, and a second is likely to arise from the vibration of a metal-coordinated oxygenated product, such as Fe(II) horizontal line O horizontal line C(1) or Fe(II) horizontal line OOCR. These results provide direct insight into the mechanism of substrate oxygenation and suggest an alternative to the hydroxyl radical rebinding paradigm.
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
Piotr K
PK
Grzyska
Evan H
EH
Appelman
Robert P
RP
Hausinger
Denis A
DA
Proshlyakov
D002384:Catalysis; D049308:Dioxygenases / Q000378:metabolism*; D005290:Ferric Compounds / Q000378:metabolism*; D010103:Oxygen Isotopes; D013059:Spectrum Analysis, Raman; D013379:Substrate Specificity
D005290:Ferric Compounds; D010103:Oxygen Isotopes; C000499:ferric oxide; D049308:Dioxygenases