Synthetic models of the active site of cytochrome c oxidase: Influence of tridentate or tetradentate copper chelates bearing a his-tyr linkage mimic on dioxygen adduct formation by heme/cu complexes

Jin Gang Liu, Yoshinori Naruta, Fumito Tani

研究成果: ジャーナルへの寄稿記事

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Two synthetic models of the active site of cytochrome c oxidase-[(L N4-OH)CuI-FeII(TMP)]+ (1a) and [(LN3-OH)CuI-FeII(TMP)]+ (2a)-have been designed and synthesized. These models each contain a heme and a covalently attached copper moiety supported either by a tetradentate N4-copper chelate or by a tridentate N3-copper chelate including a moiety that acts as a mimic of the crosslinked His-Tyr component of cytochrome c oxidase. Low-temperature oxygenation reactions of these models have been investigated by spectroscopic methods including UV/Vis, resonance Raman, ESI-MS, and EPR spectroscopy. Oxygenation of the tetradentate model la in MeCN and in other solvents produces a low-temperature-stable dioxygen-bridged peroxide [(LN4-OH)Cu II-O2-FeIII(TMP)]+ (vO-O = 799 (16O2)/752cm 1 (18O 2)), while a heme superoxide species [(TMP)FeIII(O 2-)⋯CuIILN3-OH] {v Fe-O2: 576 (16O2)/551 cm-1 ( 18O2)} is generated when the tridentate model 2 a is oxygenated in EtCN solution under similar experimental conditions. The coexistence of a heme superoxide species [(TMP)FeIII(O 2-)⋯CuIILN3-OH] and a bridged peroxide [(LN3-OH)CuII-O2-Fe III(TMP)]+ species in equal amounts is observed when the oxygenation reaction of 2 a is performed in CH2Cl2/7% EtCN, while the percentage of the peroxide (≈70%) in relation to superoxide (≈30%) increases further when the crosslinked phenol moiety in 2a is deprotonated to produce the bridged peroxide [(LN3-OH)Cu II-O2-FeIII(TMP)]+ {vO-O: 812 (16O2)/765 cm-1 (18O 2)) as the main dioxygen intermediate. The weak reducibility and decreased O2 reactivity of the tricoordinated CuI site in 2a are responsible for the solvent-dependent formation of dioxygen adducts. The initial binding of dioxygen to the copper site en route to the formation of a bridged heme-O2-Cu intermediate by model 2a is suggested and the deprotonated crosslinked His-Tyr moiety might contribute to enhancement of the O2 affinity of the Cu1 site at an early stage of the dioxygen-binding process.

元の言語英語
ページ(範囲)6365-6378
ページ数14
ジャーナルChemistry - A European Journal
13
発行部数22
DOI
出版物ステータス出版済み - 8 8 2007

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Bearings (structural)
Thymidine Monophosphate
Electron Transport Complex IV
Heme
Copper
Oxygen
Peroxides
Oxygenation
Superoxides
Phenols
Paramagnetic resonance
Phenol
Spectroscopy
Temperature

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Organic Chemistry

これを引用

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title = "Synthetic models of the active site of cytochrome c oxidase: Influence of tridentate or tetradentate copper chelates bearing a his-tyr linkage mimic on dioxygen adduct formation by heme/cu complexes",
abstract = "Two synthetic models of the active site of cytochrome c oxidase-[(L N4-OH)CuI-FeII(TMP)]+ (1a) and [(LN3-OH)CuI-FeII(TMP)]+ (2a)-have been designed and synthesized. These models each contain a heme and a covalently attached copper moiety supported either by a tetradentate N4-copper chelate or by a tridentate N3-copper chelate including a moiety that acts as a mimic of the crosslinked His-Tyr component of cytochrome c oxidase. Low-temperature oxygenation reactions of these models have been investigated by spectroscopic methods including UV/Vis, resonance Raman, ESI-MS, and EPR spectroscopy. Oxygenation of the tetradentate model la in MeCN and in other solvents produces a low-temperature-stable dioxygen-bridged peroxide [(LN4-OH)Cu II-O2-FeIII(TMP)]+ (vO-O = 799 (16O2)/752cm 1 (18O 2)), while a heme superoxide species [(TMP)FeIII(O 2-)⋯CuIILN3-OH] {v Fe-O2: 576 (16O2)/551 cm-1 ( 18O2)} is generated when the tridentate model 2 a is oxygenated in EtCN solution under similar experimental conditions. The coexistence of a heme superoxide species [(TMP)FeIII(O 2-)⋯CuIILN3-OH] and a bridged peroxide [(LN3-OH)CuII-O2-Fe III(TMP)]+ species in equal amounts is observed when the oxygenation reaction of 2 a is performed in CH2Cl2/7{\%} EtCN, while the percentage of the peroxide (≈70{\%}) in relation to superoxide (≈30{\%}) increases further when the crosslinked phenol moiety in 2a is deprotonated to produce the bridged peroxide [(LN3-OH)Cu II-O2-FeIII(TMP)]+ {vO-O: 812 (16O2)/765 cm-1 (18O 2)) as the main dioxygen intermediate. The weak reducibility and decreased O2 reactivity of the tricoordinated CuI site in 2a are responsible for the solvent-dependent formation of dioxygen adducts. The initial binding of dioxygen to the copper site en route to the formation of a bridged heme-O2-Cu intermediate by model 2a is suggested and the deprotonated crosslinked His-Tyr moiety might contribute to enhancement of the O2 affinity of the Cu1 site at an early stage of the dioxygen-binding process.",
author = "Liu, {Jin Gang} and Yoshinori Naruta and Fumito Tani",
year = "2007",
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TY - JOUR

T1 - Synthetic models of the active site of cytochrome c oxidase

T2 - Influence of tridentate or tetradentate copper chelates bearing a his-tyr linkage mimic on dioxygen adduct formation by heme/cu complexes

AU - Liu, Jin Gang

AU - Naruta, Yoshinori

AU - Tani, Fumito

PY - 2007/8/8

Y1 - 2007/8/8

N2 - Two synthetic models of the active site of cytochrome c oxidase-[(L N4-OH)CuI-FeII(TMP)]+ (1a) and [(LN3-OH)CuI-FeII(TMP)]+ (2a)-have been designed and synthesized. These models each contain a heme and a covalently attached copper moiety supported either by a tetradentate N4-copper chelate or by a tridentate N3-copper chelate including a moiety that acts as a mimic of the crosslinked His-Tyr component of cytochrome c oxidase. Low-temperature oxygenation reactions of these models have been investigated by spectroscopic methods including UV/Vis, resonance Raman, ESI-MS, and EPR spectroscopy. Oxygenation of the tetradentate model la in MeCN and in other solvents produces a low-temperature-stable dioxygen-bridged peroxide [(LN4-OH)Cu II-O2-FeIII(TMP)]+ (vO-O = 799 (16O2)/752cm 1 (18O 2)), while a heme superoxide species [(TMP)FeIII(O 2-)⋯CuIILN3-OH] {v Fe-O2: 576 (16O2)/551 cm-1 ( 18O2)} is generated when the tridentate model 2 a is oxygenated in EtCN solution under similar experimental conditions. The coexistence of a heme superoxide species [(TMP)FeIII(O 2-)⋯CuIILN3-OH] and a bridged peroxide [(LN3-OH)CuII-O2-Fe III(TMP)]+ species in equal amounts is observed when the oxygenation reaction of 2 a is performed in CH2Cl2/7% EtCN, while the percentage of the peroxide (≈70%) in relation to superoxide (≈30%) increases further when the crosslinked phenol moiety in 2a is deprotonated to produce the bridged peroxide [(LN3-OH)Cu II-O2-FeIII(TMP)]+ {vO-O: 812 (16O2)/765 cm-1 (18O 2)) as the main dioxygen intermediate. The weak reducibility and decreased O2 reactivity of the tricoordinated CuI site in 2a are responsible for the solvent-dependent formation of dioxygen adducts. The initial binding of dioxygen to the copper site en route to the formation of a bridged heme-O2-Cu intermediate by model 2a is suggested and the deprotonated crosslinked His-Tyr moiety might contribute to enhancement of the O2 affinity of the Cu1 site at an early stage of the dioxygen-binding process.

AB - Two synthetic models of the active site of cytochrome c oxidase-[(L N4-OH)CuI-FeII(TMP)]+ (1a) and [(LN3-OH)CuI-FeII(TMP)]+ (2a)-have been designed and synthesized. These models each contain a heme and a covalently attached copper moiety supported either by a tetradentate N4-copper chelate or by a tridentate N3-copper chelate including a moiety that acts as a mimic of the crosslinked His-Tyr component of cytochrome c oxidase. Low-temperature oxygenation reactions of these models have been investigated by spectroscopic methods including UV/Vis, resonance Raman, ESI-MS, and EPR spectroscopy. Oxygenation of the tetradentate model la in MeCN and in other solvents produces a low-temperature-stable dioxygen-bridged peroxide [(LN4-OH)Cu II-O2-FeIII(TMP)]+ (vO-O = 799 (16O2)/752cm 1 (18O 2)), while a heme superoxide species [(TMP)FeIII(O 2-)⋯CuIILN3-OH] {v Fe-O2: 576 (16O2)/551 cm-1 ( 18O2)} is generated when the tridentate model 2 a is oxygenated in EtCN solution under similar experimental conditions. The coexistence of a heme superoxide species [(TMP)FeIII(O 2-)⋯CuIILN3-OH] and a bridged peroxide [(LN3-OH)CuII-O2-Fe III(TMP)]+ species in equal amounts is observed when the oxygenation reaction of 2 a is performed in CH2Cl2/7% EtCN, while the percentage of the peroxide (≈70%) in relation to superoxide (≈30%) increases further when the crosslinked phenol moiety in 2a is deprotonated to produce the bridged peroxide [(LN3-OH)Cu II-O2-FeIII(TMP)]+ {vO-O: 812 (16O2)/765 cm-1 (18O 2)) as the main dioxygen intermediate. The weak reducibility and decreased O2 reactivity of the tricoordinated CuI site in 2a are responsible for the solvent-dependent formation of dioxygen adducts. The initial binding of dioxygen to the copper site en route to the formation of a bridged heme-O2-Cu intermediate by model 2a is suggested and the deprotonated crosslinked His-Tyr moiety might contribute to enhancement of the O2 affinity of the Cu1 site at an early stage of the dioxygen-binding process.

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