Nitration of γ-tocopherol and oxidation of α-tocopherol by copper- zinc superoxide dismutase/H2O2/NO2/-: Role of nitrogen dioxide free radical

Ravinder Jit Singh, S. P A Goss, J. Joseph, B. Kalyanaraman

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Abstract

Copper-zinc superoxide dismutase (Cu,Zn-SOD) is the antioxidant enzyme that catalyzes the dismutation of superoxide (O2·-) to O2 and H2O2. In addition, Cu,ZnSOD also exhibits peroxidase activity in the presence of H2O2, leading to self-inactivation and formation of a potent enzyme-bound oxidant. We report in this study that lipid peroxidation of L-α-lecithin liposomes was enhanced greatly during the SOD/H2O2 reaction in the presence of nitrite anion (NO2 -) with or without the metal ion chelator, diethylenetriaminepentacetic acid. The presence of NO2 - also greatly enhanced α-tocopherol (α-TH) oxidation by SOD/H2O2 in saturated 1,2- dilauroyl-sn-glycero-3-phosphatidylcholine liposomes. The major product identified by HPLC and UV-studies was α-tocopheryl quinone. When 1,2- diauroyl-sn-glycero-3-phosphatidylcholine liposomes containing γ-to-copherol (γ-TH) were incubated with SOD/H2O2/NO2 -, the major product identified was 5-NO2-γ-TH. Nitrone spin traps significantly inhibited the formation of α-tocopheryl quinone and 5-NO2-γ-TH. NO2 - inhibited H2O2-dependent inactivation of SOD. A proposed mechanism of this protection involves the oxidation of NO2 - by an SOD-bound oxidant to the nitrogen dioxide radical (·NO2). In this study, we have shown a new mechanism of nitration catalyzed by the peroxidase activity of SOD. We conclude that NO2 - is a suitable probe for investigating the peroxidase activity of familial Amyotrophic Lateral Sclerosis-linked SOD mutants.

Original languageEnglish (US)
Pages (from-to)12912-12917
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume95
Issue number22
DOIs
StatePublished - Oct 27 1998

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Nitrogen Dioxide
Tocopherols
Liposomes
Peroxidase
Superoxide Dismutase
Free Radicals
Zinc
Copper
Phosphatidylcholines
Oxidants
Lecithins
Enzymes
Chelating Agents
Nitrites
Superoxides
Lipid Peroxidation
Anions
Antioxidants
Metals
High Pressure Liquid Chromatography

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

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title = "Nitration of γ-tocopherol and oxidation of α-tocopherol by copper- zinc superoxide dismutase/H2O2/NO2/-: Role of nitrogen dioxide free radical",
abstract = "Copper-zinc superoxide dismutase (Cu,Zn-SOD) is the antioxidant enzyme that catalyzes the dismutation of superoxide (O2·-) to O2 and H2O2. In addition, Cu,ZnSOD also exhibits peroxidase activity in the presence of H2O2, leading to self-inactivation and formation of a potent enzyme-bound oxidant. We report in this study that lipid peroxidation of L-α-lecithin liposomes was enhanced greatly during the SOD/H2O2 reaction in the presence of nitrite anion (NO2 -) with or without the metal ion chelator, diethylenetriaminepentacetic acid. The presence of NO2 - also greatly enhanced α-tocopherol (α-TH) oxidation by SOD/H2O2 in saturated 1,2- dilauroyl-sn-glycero-3-phosphatidylcholine liposomes. The major product identified by HPLC and UV-studies was α-tocopheryl quinone. When 1,2- diauroyl-sn-glycero-3-phosphatidylcholine liposomes containing γ-to-copherol (γ-TH) were incubated with SOD/H2O2/NO2 -, the major product identified was 5-NO2-γ-TH. Nitrone spin traps significantly inhibited the formation of α-tocopheryl quinone and 5-NO2-γ-TH. NO2 - inhibited H2O2-dependent inactivation of SOD. A proposed mechanism of this protection involves the oxidation of NO2 - by an SOD-bound oxidant to the nitrogen dioxide radical (·NO2). In this study, we have shown a new mechanism of nitration catalyzed by the peroxidase activity of SOD. We conclude that NO2 - is a suitable probe for investigating the peroxidase activity of familial Amyotrophic Lateral Sclerosis-linked SOD mutants.",
author = "Singh, {Ravinder Jit} and Goss, {S. P A} and J. Joseph and B. Kalyanaraman",
year = "1998",
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doi = "10.1073/pnas.95.22.12912",
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TY - JOUR

T1 - Nitration of γ-tocopherol and oxidation of α-tocopherol by copper- zinc superoxide dismutase/H2O2/NO2/-

T2 - Role of nitrogen dioxide free radical

AU - Singh, Ravinder Jit

AU - Goss, S. P A

AU - Joseph, J.

AU - Kalyanaraman, B.

PY - 1998/10/27

Y1 - 1998/10/27

N2 - Copper-zinc superoxide dismutase (Cu,Zn-SOD) is the antioxidant enzyme that catalyzes the dismutation of superoxide (O2·-) to O2 and H2O2. In addition, Cu,ZnSOD also exhibits peroxidase activity in the presence of H2O2, leading to self-inactivation and formation of a potent enzyme-bound oxidant. We report in this study that lipid peroxidation of L-α-lecithin liposomes was enhanced greatly during the SOD/H2O2 reaction in the presence of nitrite anion (NO2 -) with or without the metal ion chelator, diethylenetriaminepentacetic acid. The presence of NO2 - also greatly enhanced α-tocopherol (α-TH) oxidation by SOD/H2O2 in saturated 1,2- dilauroyl-sn-glycero-3-phosphatidylcholine liposomes. The major product identified by HPLC and UV-studies was α-tocopheryl quinone. When 1,2- diauroyl-sn-glycero-3-phosphatidylcholine liposomes containing γ-to-copherol (γ-TH) were incubated with SOD/H2O2/NO2 -, the major product identified was 5-NO2-γ-TH. Nitrone spin traps significantly inhibited the formation of α-tocopheryl quinone and 5-NO2-γ-TH. NO2 - inhibited H2O2-dependent inactivation of SOD. A proposed mechanism of this protection involves the oxidation of NO2 - by an SOD-bound oxidant to the nitrogen dioxide radical (·NO2). In this study, we have shown a new mechanism of nitration catalyzed by the peroxidase activity of SOD. We conclude that NO2 - is a suitable probe for investigating the peroxidase activity of familial Amyotrophic Lateral Sclerosis-linked SOD mutants.

AB - Copper-zinc superoxide dismutase (Cu,Zn-SOD) is the antioxidant enzyme that catalyzes the dismutation of superoxide (O2·-) to O2 and H2O2. In addition, Cu,ZnSOD also exhibits peroxidase activity in the presence of H2O2, leading to self-inactivation and formation of a potent enzyme-bound oxidant. We report in this study that lipid peroxidation of L-α-lecithin liposomes was enhanced greatly during the SOD/H2O2 reaction in the presence of nitrite anion (NO2 -) with or without the metal ion chelator, diethylenetriaminepentacetic acid. The presence of NO2 - also greatly enhanced α-tocopherol (α-TH) oxidation by SOD/H2O2 in saturated 1,2- dilauroyl-sn-glycero-3-phosphatidylcholine liposomes. The major product identified by HPLC and UV-studies was α-tocopheryl quinone. When 1,2- diauroyl-sn-glycero-3-phosphatidylcholine liposomes containing γ-to-copherol (γ-TH) were incubated with SOD/H2O2/NO2 -, the major product identified was 5-NO2-γ-TH. Nitrone spin traps significantly inhibited the formation of α-tocopheryl quinone and 5-NO2-γ-TH. NO2 - inhibited H2O2-dependent inactivation of SOD. A proposed mechanism of this protection involves the oxidation of NO2 - by an SOD-bound oxidant to the nitrogen dioxide radical (·NO2). In this study, we have shown a new mechanism of nitration catalyzed by the peroxidase activity of SOD. We conclude that NO2 - is a suitable probe for investigating the peroxidase activity of familial Amyotrophic Lateral Sclerosis-linked SOD mutants.

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U2 - 10.1073/pnas.95.22.12912

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JF - Proceedings of the National Academy of Sciences of the United States of America

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