Magnetic circular dichroism studies on the mononuclear ferrous active site of phthalate dioxygenase from Pseudomonas cepacia show a change of ligation state on substrate binding

George T. Gassner, David P. Ballou, Gregory A. Landrum, James Whittaker

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

Phthalate dioxygenase from Pseudomonas cepacia contains a mononuclear ferrous center that is strictly required for catalytic oxygen activation. The spectroscopic characterization of this iron site and its ligand interactions has been complicated in the past by interference from a Rieske-type binuclear (2Fe-2S) cluster in the enzyme, which dominates the absorption spectra and is superimposed in X-ray absorption spectra for the mononuclear site. We have used low-temperature, variable magnetic field circular dichroism spectroscopy to selectively detect the ligand field spectra of the paramagnetic mononuclear ferrous active site in the presence of the diamagnetic exchange-coupled Rieske center and observe spectral changes associated with substrate binding. The perturbations of the d → d spectra for the mononuclear ferrous site reflect a decrease in coordination number from six to five on binding substrate. This structural change suggests that displacement of an iron ligand prepares the ferrous center for dioxygen activation.

Original languageEnglish (US)
Pages (from-to)4820-4825
Number of pages6
JournalBiochemistry
Volume32
Issue number18
StatePublished - 1993
Externally publishedYes

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Burkholderia cepacia
Circular Dichroism
Ligation
Catalytic Domain
Phase transitions
Ligands
Absorption spectra
Substrates
Iron
Chemical activation
Oxygen
Circular dichroism spectroscopy
X ray absorption
Magnetic Fields
Spectrum Analysis
X-Rays
Magnetic fields
Temperature
Enzymes
phthalate dioxygenase

ASJC Scopus subject areas

  • Biochemistry

Cite this

Magnetic circular dichroism studies on the mononuclear ferrous active site of phthalate dioxygenase from Pseudomonas cepacia show a change of ligation state on substrate binding. / Gassner, George T.; Ballou, David P.; Landrum, Gregory A.; Whittaker, James.

In: Biochemistry, Vol. 32, No. 18, 1993, p. 4820-4825.

Research output: Contribution to journalArticle

Gassner, George T. ; Ballou, David P. ; Landrum, Gregory A. ; Whittaker, James. / Magnetic circular dichroism studies on the mononuclear ferrous active site of phthalate dioxygenase from Pseudomonas cepacia show a change of ligation state on substrate binding. In: Biochemistry. 1993 ; Vol. 32, No. 18. pp. 4820-4825.
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