Electron paramagnetic resonance detection of intermediates in the enzymatic cycle of an extradiol dioxygenase

William A. Gunderson, Anna I. Zatsman, Joseph P. Emerson, Erik R. Farquhar, Lawrence Que, John D. Lipscomb, Michael P. Hendrich

Research output: Contribution to journalArticle

61 Citations (Scopus)

Abstract

Extradiol catecholic dioxygenases catalyze the cleavage of the aromatic ring of the substrate with incorporation of both oxygen atoms from O2. These enzymes are important in nature for the recovery of large amounts of carbon from aromatic compounds. The catalytic site contains either Fe or Mn coordinated by a facial triad of two His and one Glu or Asp residues. Previous studies have shown that Fe(II) and Mn(II) can be interchanged in enzymes from different organisms to catalyze similar substrate reactions. In combination, quantitative electron paramagnetic resonance spectroscopy and rapid freeze-quench experiments allow us to follow the concentrations of four different Mn species, including key metal intermediates in the catalytic cycle, as the enzyme turns over its natural substrate. Two intermediates are observed: a Mn(III)-radical species which is either Mn-superoxide or Mn-substrate radical, and a unique Mn(II) species which is involved in the rate-limiting step of the cycle and may be Mn-alkylperoxo.

Original languageEnglish (US)
Pages (from-to)14465-14467
Number of pages3
JournalJournal of the American Chemical Society
Volume130
Issue number44
DOIs
StatePublished - Nov 5 2008

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Electron Spin Resonance Spectroscopy
Paramagnetic resonance
Enzymes
Substrates
Metalloids
Superoxides
Aromatic compounds
Catalytic Domain
Spectrum Analysis
Carbon
Oxygen
Spectroscopy
Recovery
Atoms
extradiol dioxygenase
Metals
Experiments

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Electron paramagnetic resonance detection of intermediates in the enzymatic cycle of an extradiol dioxygenase. / Gunderson, William A.; Zatsman, Anna I.; Emerson, Joseph P.; Farquhar, Erik R.; Que, Lawrence; Lipscomb, John D.; Hendrich, Michael P.

In: Journal of the American Chemical Society, Vol. 130, No. 44, 05.11.2008, p. 14465-14467.

Research output: Contribution to journalArticle

Gunderson, William A. ; Zatsman, Anna I. ; Emerson, Joseph P. ; Farquhar, Erik R. ; Que, Lawrence ; Lipscomb, John D. ; Hendrich, Michael P. / Electron paramagnetic resonance detection of intermediates in the enzymatic cycle of an extradiol dioxygenase. In: Journal of the American Chemical Society. 2008 ; Vol. 130, No. 44. pp. 14465-14467.
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AU - Emerson, Joseph P.

AU - Farquhar, Erik R.

AU - Que, Lawrence

AU - Lipscomb, John D.

AU - Hendrich, Michael P.

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AB - Extradiol catecholic dioxygenases catalyze the cleavage of the aromatic ring of the substrate with incorporation of both oxygen atoms from O2. These enzymes are important in nature for the recovery of large amounts of carbon from aromatic compounds. The catalytic site contains either Fe or Mn coordinated by a facial triad of two His and one Glu or Asp residues. Previous studies have shown that Fe(II) and Mn(II) can be interchanged in enzymes from different organisms to catalyze similar substrate reactions. In combination, quantitative electron paramagnetic resonance spectroscopy and rapid freeze-quench experiments allow us to follow the concentrations of four different Mn species, including key metal intermediates in the catalytic cycle, as the enzyme turns over its natural substrate. Two intermediates are observed: a Mn(III)-radical species which is either Mn-superoxide or Mn-substrate radical, and a unique Mn(II) species which is involved in the rate-limiting step of the cycle and may be Mn-alkylperoxo.

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