English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

Cryoreduction of the NO-Adduct of Taurine:α-Ketoglutarate Dioxygenase (TauD) Yields an Elusive {FeNO}8 Species

MPS-Authors
There are no MPG-Authors in the publication available
External Resource
No external resources are shared
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available
Citation

Ye, S., Price, J. C., Barr, E. W., Green, M. T., Bollinger Jr., J. M., Krebs, C., et al. (2010). Cryoreduction of the NO-Adduct of Taurine:α-Ketoglutarate Dioxygenase (TauD) Yields an Elusive {FeNO}8 Species. Journal of the American Chemical Society, 132(13), 4739-4751. doi:10.1021/ja909715g.


Cite as: http://hdl.handle.net/21.11116/0000-0008-0FCD-2
Abstract
The Fe(II)- and α-ketoglutarate (αKG)-dependent enzymes are a functionally and mechanistically diverse group of mononuclear nonheme-iron enzymes that activate dioxygen to couple the decarboxylation of αKG, which yields succinate and CO2, to the oxidation of an aliphatic C−H bond of their substrates. Their mechanisms have been studied in detail by a combination of kinetic, spectroscopic, and computational methods. Two reaction intermediates have been trapped and characterized for several members of this enzyme family. The first intermediate is the C−H-cleaving Fe(IV)−oxo complex, which exhibits a large deuterium kinetic isotope effect on its decay. The second intermediate is a Fe(II):product complex. Reaction intermediates proposed to occur before the Fe(IV)−oxo intermediate do not accumulate and therefore cannot be characterized experimentally. One of these intermediates is the initial O2 adduct, which is a {FeO2}8 species in the notation introduced by Enemark and Feltham. Here, we report spectroscopic and computational studies on the stable NO-adduct of taurine:αKG dioxygenase (TauD), termed TauD−{FeNO}7, and its one-electron reduced form, TauD−{FeNO}8. The latter is isoelectronic with the proposed O2 adduct and was generated by low-temperature γ-irradiation of TauD−{FeNO}7. To our knowledge, TauD−{FeNO}8 is the first paramagnetic {FeNO}8 complex. The detailed analysis of experimental and computational results shows that TauD−{FeNO}8 has a triplet ground state. This has mechanistic implications that are discussed in this Article. Annealing of the triplet {FeNO}8 species presumably leads to an equally elusive {FeHNO}8 complex with a quintet ground state.