Catalytic Water Oxidation by Iridium-Modified Carbonic Anhydrase

Min Chul Kim, Sang Yup Lee

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Carbonic anhydrase (CA) is a ubiquitous metalloenzyme with a Zn cofactor coordinated to trigonal histidine imidazole moieties in a tetrahedral geometry. Removal of the Zn cofactor in CA and subsequent binding of Ir afforded CA[Ir]. Under mild and neutral conditions (30 °C, pH 7), CA[Ir] exhibited water-oxidizing activity with a turnover frequency (TOF) of 39.8 min−1, which is comparable to those of other Ir-based molecular catalysts. Coordination of Ir to the apoprotein of CA is thermodynamically preferred and is associated with an exothermic energy change (ΔH) of −10.8 kcal mol−1, which implies that the CA apoprotein is stabilized by Ir binding. The catalytic oxygen-evolving activity of CA[Ir] is displayed only if Ir is bound to CA, which functions as an effective biological scaffold that activates the Ir center for catalysis. The results of this study indicate that the histidine imidazoles at the CA active site could be exploited as beneficial biological ligands to provide unforeseen biochemical activity by coordination to a variety of transition-metal ions.

Original languageEnglish
Pages (from-to)334-341
Number of pages8
JournalChemistry - An Asian Journal
Volume13
Issue number3
DOIs
Publication statusPublished - 2018 Feb 2

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Iridium
Carbonic Anhydrases
Oxidation
Water
Apoproteins
Histidine
Imidazoles
Catalysis
Scaffolds
Transition metals
Metal ions
Catalytic Domain
Metals
Ions
Oxygen
Ligands
Catalysts
Geometry

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry
  • Organic Chemistry

Cite this

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abstract = "Carbonic anhydrase (CA) is a ubiquitous metalloenzyme with a Zn cofactor coordinated to trigonal histidine imidazole moieties in a tetrahedral geometry. Removal of the Zn cofactor in CA and subsequent binding of Ir afforded CA[Ir]. Under mild and neutral conditions (30 °C, pH 7), CA[Ir] exhibited water-oxidizing activity with a turnover frequency (TOF) of 39.8 min−1, which is comparable to those of other Ir-based molecular catalysts. Coordination of Ir to the apoprotein of CA is thermodynamically preferred and is associated with an exothermic energy change (ΔH) of −10.8 kcal mol−1, which implies that the CA apoprotein is stabilized by Ir binding. The catalytic oxygen-evolving activity of CA[Ir] is displayed only if Ir is bound to CA, which functions as an effective biological scaffold that activates the Ir center for catalysis. The results of this study indicate that the histidine imidazoles at the CA active site could be exploited as beneficial biological ligands to provide unforeseen biochemical activity by coordination to a variety of transition-metal ions.",
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Catalytic Water Oxidation by Iridium-Modified Carbonic Anhydrase. / Kim, Min Chul; Lee, Sang Yup.

In: Chemistry - An Asian Journal, Vol. 13, No. 3, 02.02.2018, p. 334-341.

Research output: Contribution to journalArticle

TY - JOUR

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N2 - Carbonic anhydrase (CA) is a ubiquitous metalloenzyme with a Zn cofactor coordinated to trigonal histidine imidazole moieties in a tetrahedral geometry. Removal of the Zn cofactor in CA and subsequent binding of Ir afforded CA[Ir]. Under mild and neutral conditions (30 °C, pH 7), CA[Ir] exhibited water-oxidizing activity with a turnover frequency (TOF) of 39.8 min−1, which is comparable to those of other Ir-based molecular catalysts. Coordination of Ir to the apoprotein of CA is thermodynamically preferred and is associated with an exothermic energy change (ΔH) of −10.8 kcal mol−1, which implies that the CA apoprotein is stabilized by Ir binding. The catalytic oxygen-evolving activity of CA[Ir] is displayed only if Ir is bound to CA, which functions as an effective biological scaffold that activates the Ir center for catalysis. The results of this study indicate that the histidine imidazoles at the CA active site could be exploited as beneficial biological ligands to provide unforeseen biochemical activity by coordination to a variety of transition-metal ions.

AB - Carbonic anhydrase (CA) is a ubiquitous metalloenzyme with a Zn cofactor coordinated to trigonal histidine imidazole moieties in a tetrahedral geometry. Removal of the Zn cofactor in CA and subsequent binding of Ir afforded CA[Ir]. Under mild and neutral conditions (30 °C, pH 7), CA[Ir] exhibited water-oxidizing activity with a turnover frequency (TOF) of 39.8 min−1, which is comparable to those of other Ir-based molecular catalysts. Coordination of Ir to the apoprotein of CA is thermodynamically preferred and is associated with an exothermic energy change (ΔH) of −10.8 kcal mol−1, which implies that the CA apoprotein is stabilized by Ir binding. The catalytic oxygen-evolving activity of CA[Ir] is displayed only if Ir is bound to CA, which functions as an effective biological scaffold that activates the Ir center for catalysis. The results of this study indicate that the histidine imidazoles at the CA active site could be exploited as beneficial biological ligands to provide unforeseen biochemical activity by coordination to a variety of transition-metal ions.

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