18O kinetic isotope effects in non-heme iron enzymes: Probing the nature of Fe/O2 intermediates

Liviu M. Mirica, Kevin P. McCusker, Jeffrey W. Munos, Hung Wen Liu, Judith P. Klinman

Research output: Contribution to journalArticle

Abstract

Contrasted here are the competitive 18O/16O kinetic isotope effects (18O KIEs) on kcat/Km(O2) for three non-heme iron enzymes that activate O2 at an iron center coordinated by a 2-His-1-carboxylate facial triad: taurine dioxygenase (TauD), (S)-(2)-hydroxypropylphosphonic acid epoxidase (HppE), and 1-aminocyclopropyl-1-carboxylic acid oxidase (ACCO). Measured 18O KIEs of 1.0102 ± 0.0002 (TauD), 1.0120 ± 0.0002 (HppE), and 1.0215 ± 0.0005 (ACCO) suggest the formation in the rate-limiting step of O2 activation of an FeIII-peroxohemiketal, FeIII-OOH, and FeIV=O species, respectively. The comparison of the measured 18O KIEs with calculated or experimental 18O equilibrium isotope effects (18O EIEs) provides new insights into the O2 activation through an inner-sphere mechanism at a non-heme iron center.

Original languageEnglish (US)
Pages (from-to)8122-8123
Number of pages2
JournalJournal of the American Chemical Society
Volume130
Issue number26
DOIs
StatePublished - Jul 2 2008
Externally publishedYes

Fingerprint

Enzyme kinetics
Isotopes
Iron
Enzymes
isotope
enzyme
Dioxygenases
iron
kinetics
Kinetics
Taurine
carboxylic acid
Carboxylic Acids
Carboxylic acids
Oxidoreductases
Chemical activation
Acids
acid
effect

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

18O kinetic isotope effects in non-heme iron enzymes : Probing the nature of Fe/O2 intermediates. / Mirica, Liviu M.; McCusker, Kevin P.; Munos, Jeffrey W.; Liu, Hung Wen; Klinman, Judith P.

In: Journal of the American Chemical Society, Vol. 130, No. 26, 02.07.2008, p. 8122-8123.

Research output: Contribution to journalArticle

Mirica, Liviu M. ; McCusker, Kevin P. ; Munos, Jeffrey W. ; Liu, Hung Wen ; Klinman, Judith P. / 18O kinetic isotope effects in non-heme iron enzymes : Probing the nature of Fe/O2 intermediates. In: Journal of the American Chemical Society. 2008 ; Vol. 130, No. 26. pp. 8122-8123.
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AU - Liu, Hung Wen

AU - Klinman, Judith P.

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