Direct real-time evaluation of nitration with green fluorescent protein in solution and within human cells reveals the impact of nitrogen dioxide vs. peroxynitrite mechanisms

Michael Graham Espey, Sandhya Xavier, Douglas D. Thomas, Katrina M Miranda, David A. Wink

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87 Citations (Scopus)

Abstract

3-Nitrotyrosyl adducts in proteins have been detected in a wide range of diseases. The mechanisms by which reactive nitrogen oxide species may impede protein function through nitration were examined by using a unique model system, which exploits a critical tyrosyl residue in the fluorophoric pocket of recombinant green fluorescent protein (GFP). Exposure of purified GFP suspended in phosphate buffer to synthetic peroxynitrite in either 0.5 or 5 μM steps resulted in progressively increased 3-nitrotyrosyl immunoreactivity concomitant with disappearance of intrinsic fluorescence (IC50 ≈ 20 μM). Fluorescence from an equivalent amount of GFP expressed within intact MCF-7 tumor cells was largely resistant to this bolus treatment (IC50 > 250 μM). The more physiologically relevant conditions of either peroxynitrite infusion (1 μM/min) or de novo formation by simultaneous, equimolar generation of nitric oxide (NO) and superoxide (e.g., 3-morpholinosydnonimine; NONOates plus xanthine oxidase/hypoxanthine, menadione, or mitomycin C) were examined. Despite robust oxidation of dihydrorhodamine under each of these conditions, fluorescence decrease of both purified and intracellular GFP was not evident regardless of carbon dioxide presence, suggesting that oxidation and nitration are not necessarily coupled. Alternatively, both extra- and intracellular GFP fluorescence was exquisitely sensitive to nitration produced by heme-peroxidase/hydrogen peroxidecatalyzed oxidation of nitrite. Formation of nitrogen dioxide (NO2) during the reaction between NO and the nitroxide 2-phenyl-4,4,5,5-tetramethylimidazole-1-oxyl 3-oxide indicated that NO2 can enter cells and alter peptide function through tyrosyl nitration. Taken together, these findings exemplified that heme-peroxidasecatalyzed formation of NO2 may play a pivotal role in inflammatory and chronic disease settings while calling into question the significance of nitration by peroxynitrite.

Original languageEnglish (US)
Pages (from-to)3481-3486
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume99
Issue number6
DOIs
StatePublished - Mar 19 2002
Externally publishedYes

Fingerprint

Nitrogen Dioxide
Peroxynitrous Acid
Green Fluorescent Proteins
Fluorescence
Nitric Oxide
Heme
Inhibitory Concentration 50
Vitamin K 3
Reactive Nitrogen Species
Xanthine Oxidase
MCF-7 Cells
Mitomycin
Nitrites
Recombinant Proteins
Carbon Dioxide
Superoxides
Oxides
Peroxidase
Hydrogen
Buffers

Keywords

  • 3-nitrotyrosine
  • Myeloperoxidase
  • Nitric oxide
  • Superoxide
  • Xanthine oxidase

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

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title = "Direct real-time evaluation of nitration with green fluorescent protein in solution and within human cells reveals the impact of nitrogen dioxide vs. peroxynitrite mechanisms",
abstract = "3-Nitrotyrosyl adducts in proteins have been detected in a wide range of diseases. The mechanisms by which reactive nitrogen oxide species may impede protein function through nitration were examined by using a unique model system, which exploits a critical tyrosyl residue in the fluorophoric pocket of recombinant green fluorescent protein (GFP). Exposure of purified GFP suspended in phosphate buffer to synthetic peroxynitrite in either 0.5 or 5 μM steps resulted in progressively increased 3-nitrotyrosyl immunoreactivity concomitant with disappearance of intrinsic fluorescence (IC50 ≈ 20 μM). Fluorescence from an equivalent amount of GFP expressed within intact MCF-7 tumor cells was largely resistant to this bolus treatment (IC50 > 250 μM). The more physiologically relevant conditions of either peroxynitrite infusion (1 μM/min) or de novo formation by simultaneous, equimolar generation of nitric oxide (NO) and superoxide (e.g., 3-morpholinosydnonimine; NONOates plus xanthine oxidase/hypoxanthine, menadione, or mitomycin C) were examined. Despite robust oxidation of dihydrorhodamine under each of these conditions, fluorescence decrease of both purified and intracellular GFP was not evident regardless of carbon dioxide presence, suggesting that oxidation and nitration are not necessarily coupled. Alternatively, both extra- and intracellular GFP fluorescence was exquisitely sensitive to nitration produced by heme-peroxidase/hydrogen peroxidecatalyzed oxidation of nitrite. Formation of nitrogen dioxide (NO2) during the reaction between NO and the nitroxide 2-phenyl-4,4,5,5-tetramethylimidazole-1-oxyl 3-oxide indicated that NO2 can enter cells and alter peptide function through tyrosyl nitration. Taken together, these findings exemplified that heme-peroxidasecatalyzed formation of NO2 may play a pivotal role in inflammatory and chronic disease settings while calling into question the significance of nitration by peroxynitrite.",
keywords = "3-nitrotyrosine, Myeloperoxidase, Nitric oxide, Superoxide, Xanthine oxidase",
author = "Espey, {Michael Graham} and Sandhya Xavier and Thomas, {Douglas D.} and Miranda, {Katrina M} and Wink, {David A.}",
year = "2002",
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language = "English (US)",
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TY - JOUR

T1 - Direct real-time evaluation of nitration with green fluorescent protein in solution and within human cells reveals the impact of nitrogen dioxide vs. peroxynitrite mechanisms

AU - Espey, Michael Graham

AU - Xavier, Sandhya

AU - Thomas, Douglas D.

AU - Miranda, Katrina M

AU - Wink, David A.

PY - 2002/3/19

Y1 - 2002/3/19

N2 - 3-Nitrotyrosyl adducts in proteins have been detected in a wide range of diseases. The mechanisms by which reactive nitrogen oxide species may impede protein function through nitration were examined by using a unique model system, which exploits a critical tyrosyl residue in the fluorophoric pocket of recombinant green fluorescent protein (GFP). Exposure of purified GFP suspended in phosphate buffer to synthetic peroxynitrite in either 0.5 or 5 μM steps resulted in progressively increased 3-nitrotyrosyl immunoreactivity concomitant with disappearance of intrinsic fluorescence (IC50 ≈ 20 μM). Fluorescence from an equivalent amount of GFP expressed within intact MCF-7 tumor cells was largely resistant to this bolus treatment (IC50 > 250 μM). The more physiologically relevant conditions of either peroxynitrite infusion (1 μM/min) or de novo formation by simultaneous, equimolar generation of nitric oxide (NO) and superoxide (e.g., 3-morpholinosydnonimine; NONOates plus xanthine oxidase/hypoxanthine, menadione, or mitomycin C) were examined. Despite robust oxidation of dihydrorhodamine under each of these conditions, fluorescence decrease of both purified and intracellular GFP was not evident regardless of carbon dioxide presence, suggesting that oxidation and nitration are not necessarily coupled. Alternatively, both extra- and intracellular GFP fluorescence was exquisitely sensitive to nitration produced by heme-peroxidase/hydrogen peroxidecatalyzed oxidation of nitrite. Formation of nitrogen dioxide (NO2) during the reaction between NO and the nitroxide 2-phenyl-4,4,5,5-tetramethylimidazole-1-oxyl 3-oxide indicated that NO2 can enter cells and alter peptide function through tyrosyl nitration. Taken together, these findings exemplified that heme-peroxidasecatalyzed formation of NO2 may play a pivotal role in inflammatory and chronic disease settings while calling into question the significance of nitration by peroxynitrite.

AB - 3-Nitrotyrosyl adducts in proteins have been detected in a wide range of diseases. The mechanisms by which reactive nitrogen oxide species may impede protein function through nitration were examined by using a unique model system, which exploits a critical tyrosyl residue in the fluorophoric pocket of recombinant green fluorescent protein (GFP). Exposure of purified GFP suspended in phosphate buffer to synthetic peroxynitrite in either 0.5 or 5 μM steps resulted in progressively increased 3-nitrotyrosyl immunoreactivity concomitant with disappearance of intrinsic fluorescence (IC50 ≈ 20 μM). Fluorescence from an equivalent amount of GFP expressed within intact MCF-7 tumor cells was largely resistant to this bolus treatment (IC50 > 250 μM). The more physiologically relevant conditions of either peroxynitrite infusion (1 μM/min) or de novo formation by simultaneous, equimolar generation of nitric oxide (NO) and superoxide (e.g., 3-morpholinosydnonimine; NONOates plus xanthine oxidase/hypoxanthine, menadione, or mitomycin C) were examined. Despite robust oxidation of dihydrorhodamine under each of these conditions, fluorescence decrease of both purified and intracellular GFP was not evident regardless of carbon dioxide presence, suggesting that oxidation and nitration are not necessarily coupled. Alternatively, both extra- and intracellular GFP fluorescence was exquisitely sensitive to nitration produced by heme-peroxidase/hydrogen peroxidecatalyzed oxidation of nitrite. Formation of nitrogen dioxide (NO2) during the reaction between NO and the nitroxide 2-phenyl-4,4,5,5-tetramethylimidazole-1-oxyl 3-oxide indicated that NO2 can enter cells and alter peptide function through tyrosyl nitration. Taken together, these findings exemplified that heme-peroxidasecatalyzed formation of NO2 may play a pivotal role in inflammatory and chronic disease settings while calling into question the significance of nitration by peroxynitrite.

KW - 3-nitrotyrosine

KW - Myeloperoxidase

KW - Nitric oxide

KW - Superoxide

KW - Xanthine oxidase

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U2 - 10.1073/pnas.062604199

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

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

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