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Janisse SE, Sharma VA, Caceres A, Medici V, Heffern MC. Systematic Evaluation of Copper(II)-Loaded Immobilized Metal Affinity Chromatography For Selective Enrichment of Copper-Binding Species in Human Serum and Plasma. Metallomics 2022; 14:6656374. [PMID: 35929804 PMCID: PMC9434637 DOI: 10.1093/mtomcs/mfac059] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 07/20/2022] [Indexed: 11/12/2022]
Abstract
Copper is essential in a host of biological processes, and disruption of its homeostasis is associated with diseases including neurodegeneration and metabolic disorders. Extracellular copper shifts in its speciation between healthy and disease states, and identifying molecular components involved in these perturbations could widen the panel of biomarkers for copper status. While there have been exciting advances in approaches for studying the extracellular proteome with mass-spectrometry-based methods, the typical workflows disrupt metal-protein interactions due to the lability of these bonds either during sample preparation or in gas-phase environments. We sought to develop and apply a workflow to enrich for and identify protein populations with copper-binding propensities in extracellular fluids using an immobilized metal affinity chromatography (IMAC) resin. The strategy was optimized using human serum to allow for maximum quantity and diversity of protein enrichment. Protein populations could be differentiated based on protein load on the resin, likely on account of differences in abundance and affinity. The enrichment workflow was applied to plasma samples from patients with Wilson disease (WD) and protein IDs and differential abundancies compared to healthy subjects were compared to those yielded from a traditional proteomic workflow. While the IMAC workflow preserved differential abundance and protein ID information from the traditional workflow, it identified several additional proteins being differentially abundant including those involved in lipid metabolism, immune system, and antioxidant pathways. Our results suggest the potential for this IMAC workflow to identify new proteins as potential biomarkers in copper-associated disease states.
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Affiliation(s)
- Samuel E Janisse
- Department of Chemistry, University of California Davis, One Shields Drive, Davis, CA 95616, USA
| | - Vibha A Sharma
- Department of Chemistry, University of California Davis, One Shields Drive, Davis, CA 95616, USA
| | - Amanda Caceres
- Department of Chemistry, University of California Davis, One Shields Drive, Davis, CA 95616, USA
| | - Valentina Medici
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, University of California Davis, 4150 V Street, PSSB Suite 3500, Sacramento, CA 95817, USA
| | - Marie C Heffern
- Department of Chemistry, University of California Davis, One Shields Drive, Davis, CA 95616, USA
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2
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Vazquez MM, Gutierrez MV, Salvatore SR, Puiatti M, Dato VA, Chiabrando GA, Freeman BA, Schopfer FJ, Bonacci G. Nitro-oleic acid, a ligand of CD36, reduces cholesterol accumulation by modulating oxidized-LDL uptake and cholesterol efflux in RAW264.7 macrophages. Redox Biol 2020; 36:101591. [PMID: 32531545 PMCID: PMC7287307 DOI: 10.1016/j.redox.2020.101591] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 01/09/2023] Open
Abstract
Macrophages play a pivotal role in the early stages of atherosclerosis development; they excessively accumulate cholesterol in the cytosol in response to modified Low Density Lipoprotein (mLDL). The mLDL are incorporated through scavenger receptors. CD36 is a high-affinity cell surface scavenger receptor that facilitates the binding and uptake of long-chain fatty acids and mLDL into the cell. Numerous structurally diverse ligands can initiate signaling responses through CD36 to regulate cell metabolism, migration, and angiogenesis. Nitro-fatty acids are endogenous electrophilic lipid mediators that react with and modulate the function of multiple enzymes and transcriptional regulatory proteins. These actions induce the expression of several anti-inflammatory and cytoprotective genes and limit pathologic responses in experimental models of atherosclerosis, cardiac ischemia/reperfusion, and inflammatory diseases. Pharmacological and genetic approaches were used to explore the actions of nitro-oleic acid (NO2-OA) on macrophage lipid metabolism. Pure synthetic NO2-OA dose-dependently increased CD36 expression in RAW264.7 macrophages and this up-regulation was abrogated in BMDM from Nrf2-KO mice. Ligand binding analysis revealed that NO2-OA specifically interacts with CD36, thus limiting the binding and uptake of mLDL. Docking analysis shows that NO2-OA establishes a low binding energy interaction with the alpha helix containing Lys164 in CD36. NO2-OA also restored autophagy flux in mLDL-loaded macrophages, thus reversing cholesterol deposition within the cell. In aggregate, these results indicate that NO2-OA reduces cholesterol uptake by binding to CD36 and increases cholesterol efflux by restoring autophagy.
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Affiliation(s)
- Matias M Vazquez
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina; Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina
| | - Maria V Gutierrez
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina; Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina
| | - Sonia R Salvatore
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, 15261, United States
| | - Marcelo Puiatti
- Departamento de Química Orgánica, INFIQC, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Virginia Actis Dato
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina; Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina
| | - Gustavo A Chiabrando
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina; Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina
| | - Bruce A Freeman
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, 15261, United States
| | - Francisco J Schopfer
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, 15261, United States
| | - Gustavo Bonacci
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina; Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina.
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3
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Protection of natural antioxidants against low-density lipoprotein oxidation. ADVANCES IN FOOD AND NUTRITION RESEARCH 2020. [PMID: 32711864 DOI: 10.1016/bs.afnr.2020.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
This chapter reports essential information about the protective action of antioxidants against LDL oxidation. The activity of individual compounds (tocopherols, vitamin C, phenolic compounds) as well as extracts obtained from plant material (cereals, fruits, legumes, nuts, mushrooms, by-products of food industry) is reported. The structure-antioxidant activity relationship of phenolic compounds is discussed. This article summarizes the findings to date of both in vitro and in vivo studies using foods or phenolic extracts isolated from foodstuffs at inhibiting the incidence of LDL oxidation. This chapter summarizes also the reportings to date of in vivo studies using foods or beverages at inhibiting the incidence of LDL oxidation.
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4
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Rodriguez-Duarte J, Galliussi G, Dapueto R, Rossello J, Malacrida L, Kamaid A, Schopfer FJ, Escande C, López GV, Batthyány C. A novel nitroalkene-α-tocopherol analogue inhibits inflammation and ameliorates atherosclerosis in Apo E knockout mice. Br J Pharmacol 2019; 176:757-772. [PMID: 30588602 DOI: 10.1111/bph.14561] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 11/30/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND PURPOSE Atherosclerosis is characterized by chronic low-grade inflammation with concomitant lipid accumulation in the arterial wall. Anti-inflammatory and anti-atherogenic properties have been described for a novel class of endogenous nitroalkenes (nitrated-unsaturated fatty acids), formed during inflammation and digestion/absorption processes. The lipid-associated antioxidant α-tocopherol is transported systemically by LDL particles including to the atheroma lesions. To capitalize on the overlapping and complementary salutary properties of endogenous nitroalkenes and α-tocopherol, we designed and synthesized a novel nitroalkene-α-tocopherol analogue (NATOH) to address chronic inflammation and atherosclerosis, particularly at the lesion sites. EXPERIMENTAL APPROACH We synthesized NATOH, determined its electrophilicity and antioxidant capacity and studied its effects over pro-inflammatory and cytoprotective pathways in macrophages in vitro. Moreover, we demonstrated its incorporation into lipoproteins and tissue both in vitro and in vivo, and determined its effect on atherosclerosis and inflammatory responses in vivo using the Apo E knockout mice model. KEY RESULTS NATOH exhibited similar antioxidant capacity to α-tocopherol and, due to the presence of the nitroalkenyl group, like endogenous nitroalkenes, it exerted electrophilic reactivity. NATOH was incorporated in vivo into the VLDL/LDL lipoproteins particles to reach the atheroma lesions. Furthermore, oral administration of NATOH down-regulated NF-κB-dependent expression of pro-inflammatory markers (including IL-1β and adhesion molecules) and ameliorated atherosclerosis in Apo E knockout mice. CONCLUSIONS AND IMPLICATIONS In toto, the data demonstrate a novel pharmacological strategy for the prevention of atherosclerosis based on a creative, natural and safe drug delivery system of a non-conventional anti-inflammatory compound (NATOH) with significant potential for clinical application.
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Affiliation(s)
- Jorge Rodriguez-Duarte
- Laboratory of Vascular Biology and Drug Development, INDICYO Program, Institut Pasteur de Montevideo, Montevideo, Uruguay.,Departmento de Química Orgánica, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - Germán Galliussi
- Laboratory of Vascular Biology and Drug Development, INDICYO Program, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Rosina Dapueto
- Laboratory of Vascular Biology and Drug Development, INDICYO Program, Institut Pasteur de Montevideo, Montevideo, Uruguay.,Departmento de Química Orgánica, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - Jessica Rossello
- Analytical Biochemistry and Proteomics Unit, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Leonel Malacrida
- Analytical Biochemistry and Proteomics Unit, Institut Pasteur de Montevideo, Montevideo, Uruguay.,Pathophysiology Department, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Andrés Kamaid
- Analytical Biochemistry and Proteomics Unit, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Francisco J Schopfer
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Carlos Escande
- Laboratory of Metabolic Diseases and Aging, INDICYO Program, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Gloria V López
- Laboratory of Vascular Biology and Drug Development, INDICYO Program, Institut Pasteur de Montevideo, Montevideo, Uruguay.,Departmento de Química Orgánica, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - Carlos Batthyány
- Laboratory of Vascular Biology and Drug Development, INDICYO Program, Institut Pasteur de Montevideo, Montevideo, Uruguay.,Analytical Biochemistry and Proteomics Unit, Institut Pasteur de Montevideo, Montevideo, Uruguay
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5
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Ehrenshaft M, Deterding LJ, Mason RP. Tripping up Trp: Modification of protein tryptophan residues by reactive oxygen species, modes of detection, and biological consequences. Free Radic Biol Med 2015; 89:220-8. [PMID: 26393422 PMCID: PMC4684788 DOI: 10.1016/j.freeradbiomed.2015.08.003] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 08/07/2015] [Accepted: 08/08/2015] [Indexed: 01/22/2023]
Abstract
Proteins comprise a majority of the dry weight of a cell, rendering them a major target for oxidative modification. Oxidation of proteins can result in significant alterations in protein molecular mass such as breakage of the polypeptide backbone and/or polymerization of monomers into dimers, multimers, and sometimes insoluble aggregates. Protein oxidation can also result in structural changes to amino acid residue side chains, conversions that have only a modest effect on protein size but can have widespread consequences for protein function. There are a wide range of rate constants for amino acid reactivity, with cysteine, methionine, tyrosine, phenylalanine, and tryptophan having the highest rate constants with commonly encountered biological oxidants. Free tryptophan and tryptophan protein residues react at a diffusion-limited rate with hydroxyl radical and also have high rate constants for reactions with singlet oxygen and ozone. Although oxidation of proteins in general and tryptophan residues specifically can have effects detrimental to the health of cells and organisms, some modifications are neutral, whereas others contribute to the function of the protein in question or may act as a signal that damaged proteins need to be replaced. This review provides a brief overview of the chemical mechanisms by which tryptophan residues become oxidized, presents both the strengths and the weaknesses of some of the techniques used to detect these oxidative interactions, and discusses selected examples of the biological consequences of tryptophan oxidation in proteins from animals, plants, and microbes.
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Affiliation(s)
- Marilyn Ehrenshaft
- Immunity, Inflammation and Disease Laboratory and National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
| | - Leesa J Deterding
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Ronald P Mason
- Immunity, Inflammation and Disease Laboratory and National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
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6
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Ganini D, Mason RP. Absence of an effect of vitamin E on protein and lipid radical formation during lipoperoxidation of LDL by lipoxygenase. Free Radic Biol Med 2014; 76:61-8. [PMID: 25091900 PMCID: PMC4252844 DOI: 10.1016/j.freeradbiomed.2014.07.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 07/09/2014] [Accepted: 07/24/2014] [Indexed: 02/07/2023]
Abstract
Low-density lipoprotein (LDL) oxidation is the primary event in atherosclerosis, and LDL lipoperoxidation leads to modifications in apolipoprotein B-100 (apo B-100) and lipids. Intermediate species of lipoperoxidation are known to be able to generate amino acid-centered radicals. Thus, we hypothesized that lipoperoxidation intermediates induce protein-derived free radical formation during LDL oxidation. Using DMPO and immuno-spin trapping, we detected the formation of protein free radicals on LDL incubated with Cu(2+) or the soybean lipoxidase (LPOx)/phospholipase A2 (PLA2). With low concentrations of DMPO (1mM), Cu(2+) dose-dependently induced oxidation of LDL and easily detected apo B-100 radicals. Protein radical formation in LDL incubated with Cu(2+) showed maximum yields after 30 min. In contrast, the yields of apo B-100 radicals formed by LPOx/PLA2 followed a typical enzyme-catalyzed kinetics that was unaffected by DMPO concentrations of up to 50mM. Furthermore, when we analyzed the effect of antioxidants on protein radical formation during LDL oxidation, we found that ascorbate, urate, and Trolox dose-dependently reduced apo B-100 free radical formation in LDL exposed to Cu(2+). In contrast, Trolox was the only antioxidant that even partially protected LDL from LPOx/PLA2. We also examined the kinetics of lipid radical formation and protein radical formation induced by Cu(2+) or LPOx/PLA2 for LDL supplemented with α-tocopherol. In contrast to the potent antioxidant effect of α-tocopherol on the delay of LDL oxidation induced by Cu(2+), when we used the oxidizing system LPOx/PLA2, no significant protection was detected. The lack of protection of α-tocopherol on the apo B-100 and lipid free radical formation by LPOx may explain the failure of vitamin E as a cardiovascular protective agent for humans.
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Affiliation(s)
- Douglas Ganini
- Free Radical Metabolism Section, Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
| | - Ronald P Mason
- Free Radical Metabolism Section, Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
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7
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Bonini MG, Consolaro MEL, Hart PC, Mao M, de Abreu ALP, Master AM. Redox control of enzymatic functions: The electronics of life's circuitry. IUBMB Life 2014; 66:167-181. [PMID: 24668617 DOI: 10.1002/iub.1258] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 03/06/2014] [Indexed: 12/22/2022]
Abstract
The field of redox biology has changed tremendously over the past 20 years. Formerly regarded as bi-products of the aerobic metabolism exclusively involved in tissue damage, reactive oxygen species (ROS) are now recognized as active participants of cell signaling events in health and in disease. In this sense, ROS and the more recently defined reactive nitrogen species (RNS) are, just like hormones and second messengers, acting as fundamental orchestrators of cell signaling pathways. The chemical modification of enzymes by ROS and RNS (that result in functional enzymatic alterations) accounts for a considerable fraction of the transient and persistent perturbations imposed by variations in oxidant levels. Upregulation of ROS and RNS in response to stress is a common cellular response that foments adaptation to a variety of physiologic alterations (hypoxia, hyperoxia, starvation, and cytokine production). Frequently, these are beneficial and increase the organisms' resistance against subsequent acute stress (preconditioning). Differently, the sustained ROS/RNS-dependent rerouting of signaling produces irreversible alterations in cellular functioning, often leading to pathogenic events. Thus, the duration and reversibility of protein oxidations define whether complex organisms remain "electronically" healthy. Among the 20 essential amino acids, four are particularly susceptible to oxidation: cysteine, methionine, tyrosine, and tryptophan. Here, we will critically review the mechanisms, implications, and repair systems involved in the redox modifications of these residues in proteins while analyzing well-characterized prototypic examples. Occasionally, we will discuss potential consequences of amino acid oxidation and speculate on the biologic necessity for such events in the context of adaptative redox signaling. © 2014 IUBMB Life, 66(3):167-181, 2014.
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Affiliation(s)
- Marcelo G Bonini
- Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pharmacology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Programa de Biociencias Aplicadas a Farmacia (PBF), Universidade Estadual de Maringa, Maringa, Parana, Brazil
| | - Marcia E L Consolaro
- Programa de Biociencias Aplicadas a Farmacia (PBF), Universidade Estadual de Maringa, Maringa, Parana, Brazil
| | - Peter C Hart
- Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Mao Mao
- Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pharmacology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Andre Luelsdorf Pimenta de Abreu
- Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pharmacology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Programa de Biociencias Aplicadas a Farmacia (PBF), Universidade Estadual de Maringa, Maringa, Parana, Brazil
| | - Alyssa M Master
- Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pharmacology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
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8
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Grosvenor AJ, Morton JD, Dyer JM. Profiling of residue-level photo-oxidative damage in peptides. Amino Acids 2009; 39:285-96. [PMID: 20091070 DOI: 10.1007/s00726-009-0440-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2009] [Accepted: 12/01/2009] [Indexed: 12/14/2022]
Abstract
Protein and peptide oxidation is a key feature in the progression of a variety of disease states and in the poor performance of protein-based products. The present work demonstrates a mass spectrometry-based approach to profiling degradation at the amino acid residue level. Synthetic peptides containing the photosensitive residues, tryptophan and tyrosine, were used as models for protein-bound residue photodegradation. Electrospray ionisation tandem mass spectrometry (ESI-MS/MS) was utilised to characterise and provide relative quantitative information on the formation of photoproducts localised to specific residues, including the characterisation of low abundance photomodifications not previously reported, including W + 4O modification, hydroxy-bis-tryptophandione and topaquinone. Other photoproducts observed were consistent with the formation of tyrosine-derived dihydroxyphenylalanine (dopa), trihydroxyphenylalanine, dopa-quinone and nitrotyrosine, and tryptophan-derived hydroxytryptophan, dihydroxytryptophan/N-formylkynurenine, kynurenine, hydroxyformylkynurenine, tryptophandiones, tetrahydro-beta-carboline and nitrotryptophan. This approach combined product identification and abundance tracking to generate a photodegradation profile of the model system. The profile of products formed yields information on formative mechanisms. Profiling of product formation offers new routes to identify damage markers for use in tracking and controlling oxidative damage to polypeptides.
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Affiliation(s)
- Anita J Grosvenor
- Growth and Development Section, Lincoln Research Centre, AgResearch, Lincoln, New Zealand
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9
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Ehrenshaft M, Silva SO, Perdivara I, Bilski P, Sik RH, Chignell CF, Tomer KB, Mason RP. Immunological detection of N-formylkynurenine in oxidized proteins. Free Radic Biol Med 2009; 46:1260-6. [PMID: 19353782 PMCID: PMC2891935 DOI: 10.1016/j.freeradbiomed.2009.01.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Reactions of tryptophan residues in proteins with radical and other oxidative species frequently lead to cleavage of the indole ring, modifying tryptophan residues into N-formylkynurenine (NFK) and kynurenine. Tryptophan modification has been detected in physiologically important proteins and has been associated with a number of human disease conditions. Modified residues have been identified through various combinations of proteomic analyses, tryptic digestion, HPLC, and mass spectrometry. Here we present a novel, immunological approach using polyclonal antiserum for detection of NFK. The specificity of our antiserum is confirmed using photooxidation and radical-mediated oxidation of proteins with and without tryptophan residues. The sensitivity of our antiserum is validated through detection of NFK in photooxidized myoglobin (two tryptophan residues) and in carbonate radical-oxidized human SOD1, which contains a single tryptophan residue. Analysis of photooxidized milk also shows that our antiserum can detect NFK residues in a mixture of proteins. Results from mass spectrometric analysis of photooxidized myoglobin samples corroborate the immunological data, detecting an increase in NFK content as the extent of photooxidation increases.
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Affiliation(s)
- Marilyn Ehrenshaft
- Laboratory of Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
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10
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Peroxynitrite-mediated lipid oxidation and nitration: mechanisms and consequences. Arch Biochem Biophys 2008; 484:167-72. [PMID: 19022215 DOI: 10.1016/j.abb.2008.11.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 10/30/2008] [Accepted: 11/01/2008] [Indexed: 01/22/2023]
Abstract
Lipid oxidation and nitration represents a novel area of research of relevance in the understanding of inflammatory processes. Peroxynitrite, the product of the diffusion-limited reaction between nitric oxide and superoxide anion, mediates oxidative modifications in lipid systems including cell membranes and lipoproteins. In this review, we discuss the mechanisms of lipid oxidation and nitration by peroxynitrite as well as the influence of physiological molecules and cell targets to redirect peroxynitrite reactivity. We also provide evidence to support that oxidation/nitration of lipids results in the formation of novel signaling modulators of key lipid-metabolizing enzymes.
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11
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López GV, Batthyány C, Blanco F, Botti H, Trostchansky A, Migliaro E, Radi R, González M, Cerecetto H, Rubbo H. Design, synthesis, and biological characterization of potential antiatherogenic nitric oxide releasing tocopherol analogs. Bioorg Med Chem 2005; 13:5787-96. [PMID: 15993614 DOI: 10.1016/j.bmc.2005.05.060] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2005] [Revised: 05/25/2005] [Accepted: 05/26/2005] [Indexed: 10/25/2022]
Abstract
Synthesis and biological characterization of a series of alpha-tocopherol analogs with NO-releasing capacity are reported. The selected NO-donor moieties were nitrooxy and furoxan. All products were tested for their in vitro NO-releasing capacities, vasodilating properties, and antiplatelet activity. They were also capable of preventing LDL oxidation.
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Affiliation(s)
- Gloria V López
- Departamento de Química Orgánica, Facultad de Ciencias-Facultad de Química, Universidad de la República, Montevideo, Uruguay
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12
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Mandal S, Kazmi NH, Sayre LM. Ligand dependence in the copper-catalyzed oxidation of hydroquinones. Arch Biochem Biophys 2005; 435:21-31. [PMID: 15680903 DOI: 10.1016/j.abb.2004.11.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2004] [Revised: 11/25/2004] [Indexed: 11/29/2022]
Abstract
Transition metal-mediated oxidation of hydroquinones is an important physiologic reaction, and copper(II) effectively catalyzes the reaction in phosphate-buffered saline (PBS). Studies reported herein in phosphate buffer alone demonstrate that copper(II) is an ineffective catalyst in the absence of coordinating ligands, but that 1,10-phenanthroline and histamine facilitate the copper(II)-mediated oxidation of hydroquinone and its 2,5- and 2,6-di-tert-butyl analogs to the corresponding benzoquinones. The high concentration of chloride in PBS is the key element that allows copper(II) to work in this system. Although the bis-bathocuproine disulfonate complex of Cu(II), (BC)(2)Cu(II), is a strong stoichiometric oxidant, stoichiometric amounts of copper(II) in the presence of ligands other than BC oxidize hydroquinones very slowly under anaerobic conditions. Thus, the rapid copper(II)-catalyzed reaction operating aerobically does not involve a simple ping-pong reduction of copper(II) to copper(I) by hydroquinone and reoxidation of copper(I) by O(2).
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Affiliation(s)
- Subrata Mandal
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA
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13
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Möller M, Botti H, Batthyany C, Rubbo H, Radi R, Denicola A. Direct Measurement of Nitric Oxide and Oxygen Partitioning into Liposomes and Low Density Lipoprotein. J Biol Chem 2005; 280:8850-4. [PMID: 15632138 DOI: 10.1074/jbc.m413699200] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nitric oxide (*NO) has been proposed to play a relevant role in modulating oxidative reactions in lipophilic media like biomembranes and lipoproteins. Two factors that will regulate *NO reactivity in the lipid milieu are its diffusion and solubility, but there is no data concerning the actual diffusion (D) and partition coefficients (KP) of *NO in biologically relevant hydrophobic phases. Herein, a "equilibrium-shift" method was designed to directly determine the *NO and O2 partition coefficients in liposomes and low density lipoprotein (LDL) relative to water. It was found that *NO partitions 4.4- and 3.4-fold in liposomes and LDL, respectively, whereas O2 behaves similarly with values of 3.9 and 2.9, respectively. In addition, actual diffusion coefficients in these hydrophobic phases were determined using fluorescence quenching and found that *NO diffuses approximately 2 times slower than O2 in the core of LDL and 12 times slower than in buffer (DNOLDL=3.9 x 10(-6) cm2 s(-1),DO2LDL=7.0 x 10(-6) cm2 s(-1),DNObuffer=DO2buffer=4.5 x 10(-5) cm2 s(-1)). The influence of *NO and O2 partitioning and diffusion in membranes and lipoproteins on *NO reaction with lipid radicals and auto-oxidation is discussed. Particularly, the 3-4-fold increase in O2 and *NO concentration within biological hydrophobic phases provides quantitative support for the idea of an accelerated auto-oxidation of *NO in lipid-containing structures, turning them into sites of enhanced local production of oxidant and nitrosating species.
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Affiliation(s)
- Matías Möller
- Laboratorio de Fisicoquímica Biológica, Facultad de Ciencias, Universidad de la República, 11400 Montevideo, Uruguay
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14
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Davies MJ, Hawkins CL. EPR spin trapping of protein radicals. Free Radic Biol Med 2004; 36:1072-86. [PMID: 15082061 DOI: 10.1016/j.freeradbiomed.2003.12.013] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2003] [Revised: 12/08/2003] [Accepted: 12/19/2003] [Indexed: 11/23/2022]
Abstract
Electron paramagnetic resonance (EPR) spin trapping was originally developed to aid the detection of low-molecular-mass radicals formed in chemical systems. It has subsequently found widespread use in biology and medicine for the direct detection of radical species formed during oxidative stress and via enzymatic reactions. Over the last 15 years this technique has also found increasing use in detecting and identifying radicals formed on biological macromolecules as a result of either radical reactions or enzymatic processes. Though the EPR signals that result from the trapping of large, slowly tumbling radicals are often broad and relatively poor in distinctive features, a number of techniques have been developed that allow a wealth of information to be obtained about the nature, site, and reactions of such radicals. This article summarizes recent developments in this area and reviews selected examples of radical formation on proteins.
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15
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Sanguinetti SM, Batthyány C, Trostchansky A, Botti H, López GI, Wikinski RLW, Rubbo H, Schreier LE. Nitric oxide inhibits prooxidant actions of uric acid during copper-mediated LDL oxidation. Arch Biochem Biophys 2004; 423:302-8. [PMID: 15001394 DOI: 10.1016/j.abb.2003.12.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2003] [Revised: 12/23/2003] [Indexed: 11/17/2022]
Abstract
Interactions between uric acid and physiologically relevant fluxes of nitric oxide ((?)NO) during copper-mediated low-density lipoprotein (LDL) oxidation were evaluated. In the absence of (?)NO, a dual pro- and antioxidant action of uric acid was evident: low concentrations of uric acid enhanced lipid oxidation and alpha-tocopherol consumption, while its protective role was observed at higher concentrations. The prooxidant effects of uric acid were mostly related to its copper-reducing ability to form Cu(+), an initiator of lipid oxidation processes. While the prooxidant action of uric acid was completely inhibited by (?)NO, the antioxidant action of (?)NO was slightly counterbalanced by uric acid. Enhancement of alpha-tocopherol consumption by uric acid was inhibited in the presence of (?)NO while additive antioxidant effects between (?)NO and uric acid were observed in conditions where uric acid spared alpha-tocopherol. Altogether, these results suggest that in the artery wall, the (?)NO/uric acid pair may exert antioxidant actions on LDL, even if increased amounts of redox active copper were available at conditions favoring prooxidant activities of uric acid.
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Affiliation(s)
- Silvia M Sanguinetti
- Laboratorio de Lípidos y Lipoproteínas, Departamento de Bioquímica Clínica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
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16
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Zarev S, Bonnefont-Rousselot D, Jedidi I, Cosson C, Couturier M, Legrand A, Beaudeux JL, Thérond P. Extent of copper LDL oxidation depends on oxidation time and copper/LDL ratio: chemical characterization. Arch Biochem Biophys 2003; 420:68-78. [PMID: 14622976 DOI: 10.1016/j.abb.2003.09.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The aim of our study was to determine, as a function of [Cu(2+)]/[LDL] ratios (0.5 and 0.05) and of oxidation phases, the extent of LDL oxidation by assessing the lipid and apo B oxidation products. The main results showed that: (i) kinetics of conjugated diene formation presented four phases for Cu(2+)/LDL ratio of 0.5 and two phases for [Cu(2+)]/[LDL] ratio of 0.05; (ii) oxidation product formation (cholesteryl ester and phosphatidylcholine hydroperoxides, apo B carbonyl groups) occurred early in the presence of endogenous antioxidants, under both copper oxidation conditions; (iii) apo B carbonylated fragments appeared when antioxidants were totally consumed at [Cu(2+)]/[LDL] ratio of 0.5; and (iv) antioxidant concentrations were stable, oxysterol formation was negligible, and no carbonylated fragment was detected at [Cu(2+)]/[LDL] ratio of 0.05. Depending on the copper/LDL ratio, oxidized LDL differ greatly in the nature of lipid peroxidation product and the degree of apo B fragmentation.
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Affiliation(s)
- Stéphanie Zarev
- Laboratoire de Biochimie Métabolique et Clinique, Faculté de Pharmacie, 4, avenue de l'Observatoire, 75270 Paris Cedex 06, France.
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17
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Trostchansky A, Ferrer-Sueta G, Batthyány C, Botti H, Batinić-Haberle I, Radi R, Rubbo H. Peroxynitrite flux-mediated LDL oxidation is inhibited by manganese porphyrins in the presence of uric acid. Free Radic Biol Med 2003; 35:1293-300. [PMID: 14607528 DOI: 10.1016/j.freeradbiomed.2003.07.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have studied the role of three Mn(III)porphyrins differing in charge, alkyl substituent length and reactivity, on LDL exposed to low fluxes of peroxynitrite (PN) in the presence of uric acid. Mn(III)porphyrins (5 microM, MnTE-2-PyP(5+), MnTnOct-2-PyP(5+), and MnTCPP(3-)) plus uric acid (300 microM) inhibited cholesteryl ester hydroperoxide formation, changes in REM as well as spared alpha- and gamma-tocopherol. MnTnOct-2-PyP(5+), the more lipophilic compound, was the most effective in protecting LDL lipids, while MnTCPP(3-) exerted the lesser protection. Mn(III)porphyrins react fast with PN ( approximately 10(5)-10(7) M(-1) s(-1)) to yield a O=Mn(IV) complex. The stoichiometry of uric acid consumption was approximately 1.7 moles per mol of PN, in agreement with reactions with both the O=Mn(IV) complex and nitrogen dioxide. A shift from an anti- to a pro-oxidant action of the Mn(III)porphyrin was observed after uric acid was significantly consumed, supporting competition reactions between LDL targets and uric acid for the O=Mn(IV) complex. Overall, the data is consistent with the catalytic reduction of PN in a cycle that involves a one electron oxidation of Mn(III) to Mn(IV) by PN followed by the reduction back to Mn(III) by uric acid. These antioxidant effects should predominate under in vivo conditions having plasma uric acid concentration range between 150 and 500 microM.
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Affiliation(s)
- Andrés Trostchansky
- Departamento de Bioquímica and Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
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18
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Hill BC, Becker L, Anand V, Kusmierczyk A, Marcovina SM, Rahman MN, Gabel BR, Jia Z, Boffa MB, Koschinsky ML. A role for apolipoprotein(a) in protection of the low-density lipoprotein component of lipoprotein(a) from copper-mediated oxidation. Arch Biochem Biophys 2003; 412:186-95. [PMID: 12667482 DOI: 10.1016/s0003-9861(03)00032-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Low-density lipoprotein (LDL) oxidation is stimulated by copper. Addition of a recombinant form of apolipoprotein(a) (apo(a); the distinguishing protein component of lipoprotein(a)) containing 17 plasminogen kringle IV-like domains (17K r-apo(a)) protects LDL against oxidation by copper. Protection is specific to apo(a) and is not achieved by plasminogen or serum albumin. When Cu(2+) is added to 17K r-apo(a), its intrinsic fluorescence is quenched in a concentration-dependent and saturable manner. Quenching is unchanged whether performed aerobically or anaerobically and is reversible by ethylenediaminetetraacetate, suggesting that it is due to equilibrium binding of Cu(2+) and not to oxidative destruction of tryptophan residues. The fluorescence change exhibits a sigmoid dependence on copper concentration, and time courses of quenching are complex. At copper concentrations below 10 microM there is little quenching, whereas above 10 microM quenching proceeds immediately as a double-exponential decay. The affinity and kinetics of copper binding to 17K r-apo(a) are diminished in the presence of the lysine analogue epsilon -aminocaproic acid. We propose that copper binding to the kringle domains of 17K is mediated by a His-X-His sequence that is located about 5A from the closest tryptophan residue of the lysine binding pocket. Copper binding may account for the natural resistance to copper-mediated oxidation of lipoprotein(a) relative to LDL that has been previously reported and for the protection afforded by apo(a) from copper-mediated oxidation of LDL that we describe in the present study.
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Affiliation(s)
- Bruce C Hill
- Department of Biochemistry, Queen's University, Kingston, Ont, Canada K7L 3N6
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19
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Alvarez MN, Trujillo M, Radi R. Peroxynitrite formation from biochemical and cellular fluxes of nitric oxide and superoxide. Methods Enzymol 2003; 359:353-66. [PMID: 12481586 DOI: 10.1016/s0076-6879(02)59198-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- María Noel Alvarez
- Department of Biochemistry, Universidad de la República, 11800 Montevideo, Uruguay
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20
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Rubbo H, Botti H, Batthyány C, Trostchansky A, Denicola A, Radi R. Antioxidant and diffusion properties of nitric oxide in low-density lipoprotein. Methods Enzymol 2003; 359:200-9. [PMID: 12481572 DOI: 10.1016/s0076-6879(02)59184-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Affiliation(s)
- Homero Rubbo
- Department of Biochemistry, Universidad de la República, 11800 Montevideo, Uruguay
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21
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Wang K, Subbaiah PV. Role of the interfacial binding domain in the oxidative susceptibility of lecithin:cholesterol acyltransferase. Biochem J 2002; 365:649-57. [PMID: 11966470 PMCID: PMC1222714 DOI: 10.1042/bj20020064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2002] [Revised: 04/16/2002] [Accepted: 04/19/2002] [Indexed: 11/17/2022]
Abstract
We had previously shown that the cholesterol esterification activity of lecithin:cholesterol acyltransferase (LCAT) is destroyed by oxidation, but still it retains the ability to hydrolyse water-soluble substrates. This suggested that the inactivation of the enzyme is not due to its catalytic function, but due to a loss of its hydrophobic binding. Since recent studies have shown that a tryptophan residue in the putative interfacial domain (Trp(61)) is critical for the activity, we determined the possible role of this residue in the oxidative susceptibility and substrate specificity of LCAT by site-directed mutagenesis. Deletion of Trp(61) resulted in a 56% loss of cholesterol esterification (LCAT) activity, but the phospholipase A(2) (PLA(2)) and the esterase activities of the enzyme were stimulated slightly. Replacing Trp(61) with another aromatic residue [Trp(61)-->Tyr (W61Y)] resulted in an increase in all activities (14-157%), whereas replacing it with an aliphatic residue [Trp(61)-->Gly (W61G)] caused a dramatic loss of LCAT (-90%) and PLA(2) (-82%) activities, but not the esterase activity (-5%). W61Y was the most sensitive to oxidation, whereas W61G was the most resistant, with respect to the LCAT and PLA(2) activities. However, the activities which do not involve interfacial binding, namely the esterase activity and the transesterification of short-chain phospholipids, were more resistant to oxidation in all LCATs, indicating a selective loss of the interfacial binding by oxidation. Furthermore, replacing the two cysteines (Cys(31) and Cys(184)) in the Trp(61) deletion mutant caused additional resistance of the enzyme to oxidizing agents, showing that both domains of the enzyme contribute independently to its oxidative susceptibility. Since the hydrolysis of truncated phospholipids, generated during the oxidation of low-density lipoproteins, does not require the interfacial-binding domain, our results suggest that LCAT may take part in the detoxification of these compounds even after the loss of its cholesterol esterification function.
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Affiliation(s)
- Kewei Wang
- Department of Medicine, Rush Medical College, 1653 West Congress Parkway, Chicago, IL 60612-3833, U.S.A
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22
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Pietraforte D, Turco L, Azzini E, Minetti M. On-line EPR study of free radicals induced by peroxidase/H(2)O(2) in human low-density lipoprotein. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1583:176-84. [PMID: 12117561 DOI: 10.1016/s1388-1981(02)00211-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The aim of this study was to use direct electron paramagnetic resonance (EPR) spectroscopy at 37 degrees C and spin trapping techniques to study radical species formed during horseradish peroxidase/H(2)O(2)-initiated low-density lipoprotein (LDL) oxidation. Using direct EPR, we obtained evidence for the formation not only of the alpha-tocopheroxyl radical but also of a protein radical(s), assigned to a tyrosyl radical(s) of apolipoprotein B-100 (apo B-100). Spin trapping with 2-methyl-2-nitrosopropane revealed (i) the formation of a mobile adduct with beta-hydrogen coupling assigned to a lipid radical and (ii) a partially immobilised adduct detected in LDL as well as in apo B-100, assigned after proteolytic digestion to the trapping of a radical centred on a tertiary carbon atom of an aromatic residue, probably tyrosine. Our results support the hypothesis that radicals are initiators of the oxidative process, and show that their formation is an early event in peroxidase-mediated oxidation. We also tested the effects of resveratrol (RSV), a polyphenolic antioxidant present in red wine. Our data indicate that 1-10 microM RSV is able to accelerate alpha-tocopherol consumption, conjugated dienes formation and the decay kinetics of LDL-centred radicals. Since phenols are substrates for peroxidases, this result may be ascribed to a RSV-mediated catalysis of peroxidase activity.
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Affiliation(s)
- Donatella Pietraforte
- Laboratorio di Biologia Cellulare, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy.
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23
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Knott HM, Baoutina A, Davies MJ, Dean RT. Comparative time-courses of copper-ion-mediated protein and lipid oxidation in low-density lipoprotein. Arch Biochem Biophys 2002; 400:223-32. [PMID: 12054433 DOI: 10.1016/s0003-9861(02)00018-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Free radicals damage both lipids and proteins and evidence has accumulated for the presence of both oxidised lipids and proteins in aged tissue samples as well as those from a variety of pathologies including atherosclerosis, diabetes, and Parkinson's disease. Oxidation of the protein and lipid moieties of low-density lipoprotein is of particular interest due to its potential role in the unregulated uptake of lipids and cholesterol by macrophages; this may contribute to the initial stage of foam cell formation in atherosclerosis. In the study reported here, we examined the comparative time-courses of lipid and protein oxidation during copper-ion-mediated oxidation of low-density lipoprotein. We show that there is an early, lipid-mediated loss of 40-50% of the Trp residues of the apoB100 protein. There is no comparable loss over an identical period during the copper-ion-mediated oxidation of lipid-free BSA. Concomitant with Trp loss, the antioxidant alpha-tocopherol is consumed with subsequent extensive lipid peroxidation. Further changes to the protein, including the copper-ion-dependent 3.5-fold increase in 3,4-dihydroxyphenylalanine and the copper-ion-independent 3-5-fold increase in o-tyrosine, oxidation products of Tyr and Phe, respectively, only occur after maximal lipid peroxidation. Long incubation periods result in depletion of 3,4-dihydroxyphenylalanine, presumably reflecting further oxidative changes. Overall, copper-ion-mediated oxidation of LDL appears to proceed initially by lipid radical-dependent processes, even though some of the earliest detectable changes occur on the apoB100 protein. This is followed by extensive lipid peroxidation and subsequent additional oxidation of aromatic residues on apoB100, though it is not yet clear whether this late protein oxidation is lipid-dependent or occurs as a result of direct radical attack.
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Affiliation(s)
- Heather M Knott
- Cell Biology and EPR Groups, The Heart Research Institute, 145 Missenden Road, Camperdown, NSW 2050, Australia.
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Denicola A, Batthyány C, Lissi E, Freeman BA, Rubbo H, Radi R. Diffusion of nitric oxide into low density lipoprotein. J Biol Chem 2002; 277:932-6. [PMID: 11689557 DOI: 10.1074/jbc.m106589200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A key early event in the development of atherosclerosis is the oxidation of low density lipoprotein (LDL) via different mechanisms including free radical reactions with both protein and lipid components. Nitric oxide (( small middle dot)NO) is capable of inhibiting LDL oxidation by scavenging radical species involved in oxidative chain propagation reactions. Herein, the diffusion of ( small middle dot)NO into LDL is studied by fluorescence quenching of pyrene derivatives. Selected probes 1-(pyrenyl)methyltrimethylammonium (PMTMA) and 1-(pyrenyl)-methyl-3-(9-octadecenoyloxy)-22,23-bisnor-5-cholenate (PMChO) were chosen so that they could be incorporated at different depths of the LDL particle. Indeed, PMTMA and PMChO were located in the surface and core of LDL, respectively, as indicated by changes in fluorescence spectra, fluorescence quenching studies with water-soluble quenchers and the lifetime values (tau(o)) of the excited probes. The apparent second order rate quenching constants of ( small middle dot)NO (k(NO)) for both probes were 2.6-3.8 x 10(10) m(-1) s(-1) and 1.2 x 10(10) m(-1) s(-1) in solution and native LDL, respectively, indicating that there is no significant barrier to the diffusion of ( small middle dot)NO to the surface and core of LDL. Nitric oxide was also capable of diffusing through oxidized LDL. Considering the preferential partitioning of ( small middle dot)NO in apolar milieu (6-8 for n-octanol:water) and therefore a larger ( small middle dot)NO concentration in LDL with respect to the aqueous phase, a corrected k(NO) value of approximately 0.2 x 10(10) m(-1) s(-1) can be determined, which still is sufficiently large and consistent with a facile diffusion of ( small middle dot)NO through LDL. Applying the Einstein-Smoluchowsky treatment, the apparent diffusion coefficient (D(')NO) of ( small middle dot)NO in native LDL is on average 2 x 10(-5) cm(2) s(-1), six times larger than that previously reported for erythrocyte plasma membrane. Thus, our observations support that ( small middle dot)NO readily traverses the LDL surface accessing the hydrophobic lipid core of the particle and affirm a role for ( small middle dot)NO as a major lipophilic antioxidant in LDL.
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Affiliation(s)
- Ana Denicola
- Department of Physical Biochemistry, Facultad de Ciencias, Universidad de la República, 11400 Montevideo, Uruguay
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25
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Trostchansky A, Batthyány C, Botti H, Radi R, Denicola A, Rubbo H. Formation of lipid-protein adducts in low-density lipoprotein by fluxes of peroxynitrite and its inhibition by nitric oxide. Arch Biochem Biophys 2001; 395:225-32. [PMID: 11697860 DOI: 10.1006/abbi.2001.2583] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Peroxynitrite (PN), the product of the diffusion-limited reaction between nitric oxide (*NO) and superoxide (O*-(2)), represents a relevant mediator of oxidative modifications in low-density lipoprotein (LDL). This work shows for the first time the simultaneous action of low-controlled fluxes of PN and *NO on LDL oxidation in terms of lipid and protein modifications as well as oxidized lipid-protein adduct formation. Fluxes of PN (e.g., 1 microM min(-1)) initiated lipid oxidation in LDL as measured by conjugated dienes and cholesteryl ester hydroperoxides formation. Oxidized-LDL exhibited a characteristic fluorescent emission spectra (lambda(exc) = 365 nm, lambda(max) = 417 nm) in parallel with changes in both the free amino groups content and the relative electrophoretic mobility of the particle. Physiologically relevant fluxes of *NO (80-300 nM min(-1)) potently inhibited these PN-dependent oxidative processes. These results are consistent with PN-induced adduct formation between lipid oxidation products and free amino groups of LDL in a process prevented by the simultaneous presence of *NO. The balance between rates of PN and *NO production in the vascular wall will critically determine the final extent of LDL oxidative modifications leading or not to scavenger receptor-mediated LDL uptake and foam cell formation.
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Affiliation(s)
- A Trostchansky
- Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
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