Hydrogen atom abstraction by Cu(II)- and Zn(II)-phenoxyl radical complexes, models for the active form of galactose oxidase

Masayasu Taki; Hideyuki Kumei; Shinobu Itoh; Shunichi Fukuzumi

doi:10.1016/S0162-0134(99)00198-1

Hydrogen atom abstraction by Cu(II)- and Zn(II)-phenoxyl radical complexes, models for the active form of galactose oxidase

Masayasu Taki, Hideyuki Kumei, Shinobu Itoh, Shunichi Fukuzumi

Department of Chemistry & Nanoscience

Research output: Contribution to journal › Article › peer-review

25 Scopus citations

Abstract

The Cu(II) and Zn(II) complexes of phenoxyl radical species [M(II)(L1(^.))(NO₃)]⁺ (M=Cu or Zn, L1H: 2-methylthio-4-tert-butyl-6-[[bis[2-(2-pyridyl)ethyl]amino]methyl]phenol) and [M(II)(L2(^.))(NO₃)]⁺ (M=Cu or Zn, L2H: 2,4-di-tert-butyl-6-[[bis[2-(2-pyridyl)ethyl]amino]methyl]phenol) are prepared as model complexes of the active form of galactose oxidase (GAO). Hydrogen atom abstraction of 1,4-cyclohexadiene and tert-butyl substituted phenols by the GAO model complexes proceeds very efficiently to give benzene and the corresponding phenoxyl radical or its C-C coupling dimer as the oxidation products, respectively. Kinetic analyses on the oxidation reactions have shown that the hydrogen atom abstraction of the phenol substrates is significantly enhanced by the coordinative interaction of the OH group to the metal ion center of the complex, providing valuable insight into the enzymatic mechanism of the alcohol oxidation. Details of the substrate-activation process have been discussed based on the activation parameters (ΔH(≠) and ΔS(≠)) of the reactions. Copyright (C) 1999 Elsevier Science Inc.

Original language	English
Pages (from-to)	1-5
Number of pages	5
Journal	Journal of Inorganic Biochemistry
Volume	78
Issue number	1
DOIs	https://doi.org/10.1016/S0162-0134(99)00198-1
State	Published - 15 Jan 2000

Bibliographical note

Funding Information:
The present study was financially supported in part by a Grant-in-Aid for Scientific Research on Priority Area (Molecular Biometallics: 10129218 and 11116219; Electrochemistry of Ordered Interface: 10131242 and 11118244; Creation of Delocalized Conjugated Electronic System: 10146232; Active Oxygen Species: 11228206) from the Ministry of Education, Science, Sports, and Culture of Japan, and by Research Fellowships of the Japan Society for the Promotion of Science for Young Scientists (No. 02410).

Keywords

Copper(II) complexes
Galactose oxidase model
Hydrogen atom abstraction
Phenoxyl radical
Zinc(II) complexes

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10.1016/S0162-0134(99)00198-1

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title = "Hydrogen atom abstraction by Cu(II)- and Zn(II)-phenoxyl radical complexes, models for the active form of galactose oxidase",

abstract = "The Cu(II) and Zn(II) complexes of phenoxyl radical species [M(II)(L1(.))(NO3)]+ (M=Cu or Zn, L1H: 2-methylthio-4-tert-butyl-6-[[bis[2-(2-pyridyl)ethyl]amino]methyl]phenol) and [M(II)(L2(.))(NO3)]+ (M=Cu or Zn, L2H: 2,4-di-tert-butyl-6-[[bis[2-(2-pyridyl)ethyl]amino]methyl]phenol) are prepared as model complexes of the active form of galactose oxidase (GAO). Hydrogen atom abstraction of 1,4-cyclohexadiene and tert-butyl substituted phenols by the GAO model complexes proceeds very efficiently to give benzene and the corresponding phenoxyl radical or its C-C coupling dimer as the oxidation products, respectively. Kinetic analyses on the oxidation reactions have shown that the hydrogen atom abstraction of the phenol substrates is significantly enhanced by the coordinative interaction of the OH group to the metal ion center of the complex, providing valuable insight into the enzymatic mechanism of the alcohol oxidation. Details of the substrate-activation process have been discussed based on the activation parameters (ΔH(≠) and ΔS(≠)) of the reactions. Copyright (C) 1999 Elsevier Science Inc.",

keywords = "Copper(II) complexes, Galactose oxidase model, Hydrogen atom abstraction, Phenoxyl radical, Zinc(II) complexes",

author = "Masayasu Taki and Hideyuki Kumei and Shinobu Itoh and Shunichi Fukuzumi",

note = "Funding Information: The present study was financially supported in part by a Grant-in-Aid for Scientific Research on Priority Area (Molecular Biometallics: 10129218 and 11116219; Electrochemistry of Ordered Interface: 10131242 and 11118244; Creation of Delocalized Conjugated Electronic System: 10146232; Active Oxygen Species: 11228206) from the Ministry of Education, Science, Sports, and Culture of Japan, and by Research Fellowships of the Japan Society for the Promotion of Science for Young Scientists (No. 02410).",

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doi = "10.1016/S0162-0134(99)00198-1",

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AU - Taki, Masayasu

AU - Kumei, Hideyuki

AU - Itoh, Shinobu

AU - Fukuzumi, Shunichi

N1 - Funding Information: The present study was financially supported in part by a Grant-in-Aid for Scientific Research on Priority Area (Molecular Biometallics: 10129218 and 11116219; Electrochemistry of Ordered Interface: 10131242 and 11118244; Creation of Delocalized Conjugated Electronic System: 10146232; Active Oxygen Species: 11228206) from the Ministry of Education, Science, Sports, and Culture of Japan, and by Research Fellowships of the Japan Society for the Promotion of Science for Young Scientists (No. 02410).

PY - 2000/1/15

Y1 - 2000/1/15

N2 - The Cu(II) and Zn(II) complexes of phenoxyl radical species [M(II)(L1(.))(NO3)]+ (M=Cu or Zn, L1H: 2-methylthio-4-tert-butyl-6-[[bis[2-(2-pyridyl)ethyl]amino]methyl]phenol) and [M(II)(L2(.))(NO3)]+ (M=Cu or Zn, L2H: 2,4-di-tert-butyl-6-[[bis[2-(2-pyridyl)ethyl]amino]methyl]phenol) are prepared as model complexes of the active form of galactose oxidase (GAO). Hydrogen atom abstraction of 1,4-cyclohexadiene and tert-butyl substituted phenols by the GAO model complexes proceeds very efficiently to give benzene and the corresponding phenoxyl radical or its C-C coupling dimer as the oxidation products, respectively. Kinetic analyses on the oxidation reactions have shown that the hydrogen atom abstraction of the phenol substrates is significantly enhanced by the coordinative interaction of the OH group to the metal ion center of the complex, providing valuable insight into the enzymatic mechanism of the alcohol oxidation. Details of the substrate-activation process have been discussed based on the activation parameters (ΔH(≠) and ΔS(≠)) of the reactions. Copyright (C) 1999 Elsevier Science Inc.

AB - The Cu(II) and Zn(II) complexes of phenoxyl radical species [M(II)(L1(.))(NO3)]+ (M=Cu or Zn, L1H: 2-methylthio-4-tert-butyl-6-[[bis[2-(2-pyridyl)ethyl]amino]methyl]phenol) and [M(II)(L2(.))(NO3)]+ (M=Cu or Zn, L2H: 2,4-di-tert-butyl-6-[[bis[2-(2-pyridyl)ethyl]amino]methyl]phenol) are prepared as model complexes of the active form of galactose oxidase (GAO). Hydrogen atom abstraction of 1,4-cyclohexadiene and tert-butyl substituted phenols by the GAO model complexes proceeds very efficiently to give benzene and the corresponding phenoxyl radical or its C-C coupling dimer as the oxidation products, respectively. Kinetic analyses on the oxidation reactions have shown that the hydrogen atom abstraction of the phenol substrates is significantly enhanced by the coordinative interaction of the OH group to the metal ion center of the complex, providing valuable insight into the enzymatic mechanism of the alcohol oxidation. Details of the substrate-activation process have been discussed based on the activation parameters (ΔH(≠) and ΔS(≠)) of the reactions. Copyright (C) 1999 Elsevier Science Inc.

KW - Copper(II) complexes

KW - Galactose oxidase model

KW - Hydrogen atom abstraction

KW - Phenoxyl radical

KW - Zinc(II) complexes

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AN - SCOPUS:0034651141

SN - 0162-0134

VL - 78

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JO - Journal of Inorganic Biochemistry

JF - Journal of Inorganic Biochemistry

IS - 1

ER -

Hydrogen atom abstraction by Cu(II)- and Zn(II)-phenoxyl radical complexes, models for the active form of galactose oxidase

Abstract

Bibliographical note

Keywords

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