Search results for "nitration"
showing 10 items of 34 documents
Peroxynitrite generated from constitutive nitric oxide synthase mediates the early biochemical injury in short-term cultured hepatocytes
2000
AbstractEarly loss of P450 in rat hepatocyte cultures appears directly related to nitric oxide (NO) overproduction. This study provides experimental evidence for the induction – shortly after isolation through the classical procedure – of strong oxidative stress that involves both oxygen-derived and NO-derived species. NO formation at this stage is due to the early activation of liver constitutive NO synthase (cNOS). Immunodetection of nitrated proteins provides direct evidence of endogenous peroxynitrite (PN) formation upon hepatocyte isolation. On the basis of the combined use of dihydrorhodamine 123 and NOS inhibitors, the analysis of the amount, time course and nature of the species inv…
Electrochemical nitration with nitrite
2021
Aromatic nitration has tremendous importance in organic chemistry as nitroaromatic compounds serve as versatile building blocks. This study represents the electrochemical aromatic nitration with NBu4 NO2 , which serves a dual role as supporting electrolyte and as a safe, readily available, and easy-to-handle nitro source. Stoichiometric amounts of 1,1,1-3,3,3-hexafluoroisopropan-2-ol (HFIP) in MeCN significantly increase the yield by solvent control. The reaction mechanism is based on electrochemical oxidation of nitrite to NO2 , which initiates the nitration reaction in a divided electrolysis cell with inexpensive graphite electrodes. Overall, the reaction is demonstrated for 20 examples w…
Protein Tyrosine Nitration Induced by Heme/Hydrogen Peroxide: Inhibitory Effect of Hydroxycinnamoyl Conjugates
2006
The present study was designed to optimize the experimental conditions that govern the heme-catalyzed nitration of protein tyrosine residues by nitrite, and, within this framework, to study the effects of 3,5-dicaffeoylquinic acid and its methyl ester, both of which have been previously reported to be antioxidants and inhibitors of leukocyte functions. Although the presence of hydrogen peroxide is essential in cell-free systems, an excess of this compound was found to be detrimental, so much so that an increase in hemin concentration actually resulted in an inverse effect on the reaction, depending on the levels of fixed hydrogen peroxide. Unlike previous reports on nitrite-induced albumin …
Reductive modification of genetically encoded 3-nitrotyrosine sites in alpha synuclein expressed in E.coli
2019
Tyrosine nitration is a post-translational protein modification relevant to various pathophysiological processes. Chemical nitration procedures have been used to generate and study nitrated proteins, but these methods regularly lead to modifications at other amino acid residues. A novel strategy employs a genetic code modification that allows incorporation of 3-nitrotyrosine (3-NT) during ribosomal protein synthesis to generate a recombinant protein with defined 3-NT-sites, in the absence of other post-translational modifications. This approach was applied to study the generation and stability of the 3-NT moiety in recombinant proteins produced in E.coli. Nitrated alpha-synuclein (ASYN) was…
Post-Translational Regulation of Fas/CD95 in Cell Death and Survival: Role of Nitric Oxide
2010
Understanding the Mechanism of Nitrobenzene Nitration with Nitronium Ion: A Molecular Electron Density Theory Study
2019
2017
Abstract. Proteins can be nitrated by air pollutants (NO2), enhancing their allergenic potential. This work provides insight into protein nitration and subsequent decomposition in the presence of solar radiation. We also investigated light-induced formation of nitrous acid (HONO) from protein surfaces that were nitrated either online with instantaneous gas-phase exposure to NO2 or offline by an efficient nitration agent (tetranitromethane, TNM). Bovine serum albumin (BSA) and ovalbumin (OVA) were used as model substances for proteins. Nitration degrees of about 1 % were derived applying NO2 concentrations of 100 ppb under VIS∕UV illuminated conditions, while simultaneous decomposition of (n…
Post-translational modifications of hsp60 and its extracellular release via exosomes are induced by the histone deacetylase inhibitor (HDACi) SAHA in…
2015
The chaperonin Hsp60 has multiple functions, among which that of supporting the growth of some type of tumours (1). HDACi (histone-deacetylase inhibitors) are drugs that regulate gene expression via modulation of epigenetic mechanisms, and induce tumor-cell death (2). Here, we show that in the tumor cells H292 the HDACi SAHA decreases the intracellular level of Hps60 and promotes its extracellular trafficking by exosomal vesicles. SAHA caused a time- and dose-dependent decrease in cell viability with a G/2M cell-cycle arrest at 24 h and cell death at 48 h. These effects were accompanied by production of reactive oxygen species and mitochondrial membrane-potential dissipation. The marked dec…
Protein-bound tyrosine oxidation, nitration and chlorination by-products assessed by ultraperformance liquid chromatography coupled to tandem mass sp…
2015
Abstract Background Free radicals cause alterations in cellular protein structure and function. Oxidized, nitrated, and chlorinated modifications of aromatic amino acids including phenylalanine and tyrosine are reliable biomarkers of oxidative stress and inflammation in clinical conditions. Objective To develop, validate and apply a rapid method for the quantification of known hallmarks of tyrosine oxidation, nitration and chlorination in plasma and tissue proteins providing a snapshot of the oxidative stress and inflammatory status of the organism and of target organs respectively. Material and Methods The extraction and clean up procedure entailed protein precipitation, followed by protei…
Atmospheric protein chemistry influenced by anthropogenic air pollutants: nitration and oligomerization upon exposure to ozone and nitrogen dioxide
2017
The allergenic potential of airborne proteins may be enhanced via post-translational modification induced by air pollutants like ozone (O3) and nitrogen dioxide (NO2). The molecular mechanisms and kinetics of the chemical modifications that enhance the allergenicity of proteins, however, are still not fully understood. Here, protein tyrosine nitration and oligomerization upon simultaneous exposure of O3 and NO2 were studied in coated-wall flow-tube and bulk solution experiments under varying atmospherically relevant conditions (5–200 ppb O3, 5–200 ppb NO2, 45–96% RH), using bovine serum albumin as a model protein. Generally, more tyrosine residues were found to react via the nitration pathw…