Spectroscopic Investigations of Catalase Compound II

Characterization of an Iron(IV) Hydroxide Intermediate in a Non-thiolate-Ligated Heme Enzyme

Timothy H. Yosca, Matthew C. Langston, Courtney M. Krest, Elizabeth L. Onderko, Tyler L. Grove, Jovan Livada, Michael T. Green

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

We report on the protonation state of Helicobacter pylori catalase compound II. UV/visible, Mössbauer, and X-ray absorption spectroscopies have been used to examine the intermediate from pH 5 to 14. We have determined that HPC-II exists in an iron(IV) hydroxide state up to pH 11. Above this pH, the iron(IV) hydroxide complex transitions to a new species (pK a = 13.1) with Mössbauer parameters that are indicative of an iron(IV)-oxo intermediate. Recently, we discussed a role for an elevated compound II pK a in diminishing the compound I reduction potential. This has the effect of shifting the thermodynamic landscape toward the two-electron chemistry that is critical for catalase function. In catalase, a diminished potential would increase the selectivity for peroxide disproportionation over off-pathway one-electron chemistry, reducing the buildup of the inactive compound II state and reducing the need for energetically expensive electron donor molecules.

Original languageEnglish (US)
Pages (from-to)16016-16023
Number of pages8
JournalJournal of the American Chemical Society
Volume138
Issue number49
DOIs
StatePublished - Dec 14 2016

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Heme
Catalase
Enzymes
Electrons
Iron
X-Ray Absorption Spectroscopy
X ray absorption spectroscopy
Protonation
Peroxides
Thermodynamics
Helicobacter pylori
Molecules
ferryl iron
hydroxide ion

All Science Journal Classification (ASJC) codes

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

Cite this

Yosca, Timothy H. ; Langston, Matthew C. ; Krest, Courtney M. ; Onderko, Elizabeth L. ; Grove, Tyler L. ; Livada, Jovan ; Green, Michael T. / Spectroscopic Investigations of Catalase Compound II : Characterization of an Iron(IV) Hydroxide Intermediate in a Non-thiolate-Ligated Heme Enzyme. In: Journal of the American Chemical Society. 2016 ; Vol. 138, No. 49. pp. 16016-16023.
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abstract = "We report on the protonation state of Helicobacter pylori catalase compound II. UV/visible, M{\"o}ssbauer, and X-ray absorption spectroscopies have been used to examine the intermediate from pH 5 to 14. We have determined that HPC-II exists in an iron(IV) hydroxide state up to pH 11. Above this pH, the iron(IV) hydroxide complex transitions to a new species (pK a = 13.1) with M{\"o}ssbauer parameters that are indicative of an iron(IV)-oxo intermediate. Recently, we discussed a role for an elevated compound II pK a in diminishing the compound I reduction potential. This has the effect of shifting the thermodynamic landscape toward the two-electron chemistry that is critical for catalase function. In catalase, a diminished potential would increase the selectivity for peroxide disproportionation over off-pathway one-electron chemistry, reducing the buildup of the inactive compound II state and reducing the need for energetically expensive electron donor molecules.",
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Spectroscopic Investigations of Catalase Compound II : Characterization of an Iron(IV) Hydroxide Intermediate in a Non-thiolate-Ligated Heme Enzyme. / Yosca, Timothy H.; Langston, Matthew C.; Krest, Courtney M.; Onderko, Elizabeth L.; Grove, Tyler L.; Livada, Jovan; Green, Michael T.

In: Journal of the American Chemical Society, Vol. 138, No. 49, 14.12.2016, p. 16016-16023.

Research output: Contribution to journalArticle

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AU - Livada, Jovan

AU - Green, Michael T.

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