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Radiolysis Studies of Oxidation and Nitration of Tyrosine and Some Other Biological Targets by Peroxynitrite-Derived Radicals. Int J Mol Sci 2022; 23:ijms23031797. [PMID: 35163717 PMCID: PMC8836854 DOI: 10.3390/ijms23031797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 01/31/2022] [Accepted: 02/02/2022] [Indexed: 01/27/2023] Open
Abstract
The widespread interest in free radicals in biology extends far beyond the effects of ionizing radiation, with recent attention largely focusing on reactions of free radicals derived from peroxynitrite (i.e., hydroxyl, nitrogen dioxide, and carbonate radicals). These radicals can easily be generated individually by reactions of radiolytically-produced radicals in aqueous solutions and their reactions can be monitored either in real time or by analysis of products. This review first describes the general principles of selective radical generation by radiolysis, the yields of individual species, the advantages and limitations of either pulsed or continuous radiolysis, and the quantitation of oxidizing power of radicals by electrode potentials. Some key reactions of peroxynitrite-derived radicals with potential biological targets are then discussed, including the characterization of reactions of tyrosine with a model alkoxyl radical, reactions of tyrosyl radicals with nitric oxide, and routes to nitrotyrosine formation. This is followed by a brief outline of studies involving the reactions of peroxynitrite-derived radicals with lipoic acid/dihydrolipoic acid, hydrogen sulphide, and the metal chelator desferrioxamine. For biological diagnostic probes such as ‘spin traps’ to be used with confidence, their reactivities with radical species have to be characterized, and the application of radiolysis methods in this context is also illustrated.
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Photo- and Radiation-Induced One-Electron Oxidation of Methionine in Various Structural Environments Studied by Time-Resolved Techniques. Molecules 2022; 27:molecules27031028. [PMID: 35164293 PMCID: PMC8915190 DOI: 10.3390/molecules27031028] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 01/26/2022] [Accepted: 01/27/2022] [Indexed: 11/25/2022] Open
Abstract
Oxidation of methionine (Met) is an important reaction that plays a key role in protein modifications during oxidative stress and aging. The first steps of Met oxidation involve the creation of very reactive and short-lived transients. Application of complementary time-resolved radiation and photochemical techniques (pulse radiolysis and laser flash photolysis together with time-resolved CIDNP and ESR techniques) allowed comparing in detail the one-electron oxidation mechanisms initiated either by ●OH radicals and other one-electron oxidants or the excited triplet state of the sensitizers e.g., 4-,3-carboxybenzophenones. The main purpose of this review is to present various factors that influence the character of the forming intermediates. They are divided into two parts: those inextricably related to the structures of molecules containing Met and those related to external factors. The former include (i) the protection of terminal amine and carboxyl groups, (ii) the location of Met in the peptide molecule, (iii) the character of neighboring amino acid other than Met, (iv) the character of the peptide chain (open vs cyclic), (v) the number of Met residues in peptide and protein, and (vi) the optical isomerism of Met residues. External factors include the type of the oxidant, pH, and concentration of Met-containing compounds in the reaction environment. Particular attention is given to the neighboring group participation, which is an essential parameter controlling one-electron oxidation of Met. Mechanistic aspects of oxidation processes by various one-electron oxidants in various structural and pH environments are summarized and discussed. The importance of these studies for understanding oxidation of Met in real biological systems is also addressed.
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Joshi R. Charge transfer reactions from tryptophan and tyrosine to sulfur-centered dimer radical cation in aqueous -sulfuric acid medium: a pulse radiolysis study. J PHYS ORG CHEM 2016. [DOI: 10.1002/poc.3530] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Ravi Joshi
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Mumbai 400 085 India
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Houée-Lévin C, Bobrowski K, Horakova L, Karademir B, Schöneich C, Davies MJ, Spickett CM. Exploring oxidative modifications of tyrosine: An update on mechanisms of formation, advances in analysis and biological consequences. Free Radic Res 2015; 49:347-73. [DOI: 10.3109/10715762.2015.1007968] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Augustyniak E, Adam A, Wojdyla K, Rogowska-Wrzesinska A, Willetts R, Korkmaz A, Atalay M, Weber D, Grune T, Borsa C, Gradinaru D, Chand Bollineni R, Fedorova M, Griffiths HR. Validation of protein carbonyl measurement: a multi-centre study. Redox Biol 2014; 4:149-57. [PMID: 25560243 PMCID: PMC4309846 DOI: 10.1016/j.redox.2014.12.014] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 12/21/2014] [Accepted: 12/22/2014] [Indexed: 11/02/2022] Open
Abstract
Protein carbonyls are widely analysed as a measure of protein oxidation. Several different methods exist for their determination. A previous study had described orders of magnitude variance that existed when protein carbonyls were analysed in a single laboratory by ELISA using different commercial kits. We have further explored the potential causes of variance in carbonyl analysis in a ring study. A soluble protein fraction was prepared from rat liver and exposed to 0, 5 and 15min of UV irradiation. Lyophilised preparations were distributed to six different laboratories that routinely undertook protein carbonyl analysis across Europe. ELISA and Western blotting techniques detected an increase in protein carbonyl formation between 0 and 5min of UV irradiation irrespective of method used. After irradiation for 15min, less oxidation was detected by half of the laboratories than after 5min irradiation. Three of the four ELISA carbonyl results fell within 95% confidence intervals. Likely errors in calculating absolute carbonyl values may be attributed to differences in standardisation. Out of up to 88 proteins identified as containing carbonyl groups after tryptic cleavage of irradiated and control liver proteins, only seven were common in all three liver preparations. Lysine and arginine residues modified by carbonyls are likely to be resistant to tryptic proteolysis. Use of a cocktail of proteases may increase the recovery of oxidised peptides. In conclusion, standardisation is critical for carbonyl analysis and heavily oxidised proteins may not be effectively analysed by any existing technique.
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Affiliation(s)
| | - Aisha Adam
- Life & Health Sciences, Aston University, Birmingham B4 7ET, UK
| | - Katarzyna Wojdyla
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Denmark
| | | | - Rachel Willetts
- Life & Health Sciences, Aston University, Birmingham B4 7ET, UK
| | - Ayhan Korkmaz
- University of Eastern Finland, Institute of Biomedicine, Physiology, Finland
| | - Mustafa Atalay
- Institute of Biomedicine, Physiology, University of Kuopio, Kuopio, Finland
| | - Daniela Weber
- German Institute of Human Nutrition, DIfE, Nuthetal 14558, Germany
| | - Tilman Grune
- German Institute of Human Nutrition, DIfE, Nuthetal 14558, Germany
| | - Claudia Borsa
- Ana Aslan - National Institute of Gerontology and Geriatrics, PO Box 2-4, Bucharest 011241, Romania
| | - Daniela Gradinaru
- Faculty of Pharmacy, Department of Biochemistry, Carol Davila - University of Medicine and Pharmacy, Bucharest 020956, Romania
| | - Ravi Chand Bollineni
- Faculty of Chemistry and Mineralogy, Center for Biotechnology and Biomedicine, Institute of Bioanalytical Chemistry, Universität Leipzig, Leipzig, Germany
| | - Maria Fedorova
- Faculty of Chemistry and Mineralogy, Center for Biotechnology and Biomedicine, Institute of Bioanalytical Chemistry, Universität Leipzig, Leipzig, Germany
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Ignasiak MT, Marciniak B, Houée-Levin C. A Long Story of Sensitized One-Electron Photo-oxidation of Methionine. Isr J Chem 2014. [DOI: 10.1002/ijch.201300109] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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7
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Houée-Levin C, Bobrowski K. The use of the methods of radiolysis to explore the mechanisms of free radical modifications in proteins. J Proteomics 2013; 92:51-62. [PMID: 23454334 DOI: 10.1016/j.jprot.2013.02.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 02/01/2013] [Accepted: 02/02/2013] [Indexed: 10/27/2022]
Abstract
The method of radiolysis is based upon the interaction of ionising radiation with the solvent (water). One can form the same free radicals as in conditions of oxidative stress ((•)OH, O2(•)(-), NO2(•)…). Moreover, the quantity of reactive oxygen (ROS) or nitrogen (RNS) species formed in the irradiated medium can be calculated knowing the dose and the radiation chemical yield, G, thus this method is quantitative. The use of the method of radiolysis has provided a wealth of data, especially about the kinetics of the oxidation by various free radicals and their mechanisms, the identification of transients formed, their lifetimes and the possibility to repair them by the so-called antioxidants. In this review we have collected the most recent data about protein oxidation that might be useful to a proteomic approach. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.
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Affiliation(s)
- Chantal Houée-Levin
- Laboratoire de Chimie Physique, UMR 8000, Université Paris Sud, (France), also at CNRS, France
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8
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Mozziconacci O, Mirkowski J, Rusconi F, Kciuk G, Wisniowski PB, Bobrowski K, Houée-Levin C. Methionine Residue Acts as a Prooxidant in the •OH-Induced Oxidation of Enkephalins. J Phys Chem B 2012; 116:12460-72. [DOI: 10.1021/jp307043q] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Olivier Mozziconacci
- Laboratory of Physical Chemistry and CNRS Bldg 350, Centre Universitaire, F-91405
Orsay, F-91405 Orsay, France
- Institute of Nuclear Chemistry and Technology, Dorodna, 16, 03-195 Warsaw,
Poland
- Department
of Pharmaceutical
Chemistry, University of Kansas, Lawrence, Kansas 66047, United States
| | - Jacek Mirkowski
- Institute of Nuclear Chemistry and Technology, Dorodna, 16, 03-195 Warsaw,
Poland
| | - Filippo Rusconi
- Laboratory of Physical Chemistry and CNRS Bldg 350, Centre Universitaire, F-91405
Orsay, F-91405 Orsay, France
- Muséum National d’Histoire
Naturelle, CNRS, UMR7196 - INSERM, U565 - MNHN USM0503, 57 rue Cuvier, F-75231 Paris Cedex-05, France
| | - Gabriel Kciuk
- Institute of Nuclear Chemistry and Technology, Dorodna, 16, 03-195 Warsaw,
Poland
| | - Pawel B. Wisniowski
- Institute of Nuclear Chemistry and Technology, Dorodna, 16, 03-195 Warsaw,
Poland
| | - Krzysztof Bobrowski
- Institute of Nuclear Chemistry and Technology, Dorodna, 16, 03-195 Warsaw,
Poland
| | - Chantal Houée-Levin
- Laboratory of Physical Chemistry and CNRS Bldg 350, Centre Universitaire, F-91405
Orsay, F-91405 Orsay, France
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Petruk AA, Bartesaghi S, Trujillo M, Estrin DA, Murgida D, Kalyanaraman B, Marti MA, Radi R. Molecular basis of intramolecular electron transfer in proteins during radical-mediated oxidations: computer simulation studies in model tyrosine-cysteine peptides in solution. Arch Biochem Biophys 2012; 525:82-91. [PMID: 22640642 DOI: 10.1016/j.abb.2012.05.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 05/05/2012] [Accepted: 05/20/2012] [Indexed: 11/15/2022]
Abstract
Experimental studies in hemeproteins and model Tyr/Cys-containing peptides exposed to oxidizing and nitrating species suggest that intramolecular electron transfer (IET) between tyrosyl radicals (Tyr-O(·)) and Cys residues controls oxidative modification yields. The molecular basis of this IET process is not sufficiently understood with structural atomic detail. Herein, we analyzed using molecular dynamics and quantum mechanics-based computational calculations, mechanistic possibilities for the radical transfer reaction in Tyr/Cys-containing peptides in solution and correlated them with existing experimental data. Our results support that Tyr-O(·) to Cys radical transfer is mediated by an acid/base equilibrium that involves deprotonation of Cys to form the thiolate, followed by a likely rate-limiting transfer process to yield cysteinyl radical and a Tyr phenolate; proton uptake by Tyr completes the reaction. Both, the pKa values of the Tyr phenol and Cys thiol groups and the energetic and kinetics of the reversible IET are revealed as key physico-chemical factors. The proposed mechanism constitutes a case of sequential, acid/base equilibrium-dependent and solvent-mediated, proton-coupled electron transfer and explains the dependency of oxidative yields in Tyr/Cys peptides as a function of the number of alanine spacers. These findings contribute to explain oxidative modifications in proteins that contain sequence and/or spatially close Tyr-Cys residues.
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Affiliation(s)
- Ariel A Petruk
- Instituto Superior de Investigaciones Biológicas (CONICET-UNT), Chacabuco 461, S.M. de Tucumán, Tucumán, T4000CAN, Argentina
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Pulse radiolysis studies of intermolecular charge transfers involving tryptophan and three-electron-bonded intermediates derived from methionine. RESEARCH ON CHEMICAL INTERMEDIATES 2011. [DOI: 10.1007/s11164-011-0331-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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11
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Bergès J, Trouillas P, Houée-Levin C. Oxidation of protein tyrosine or methionine residues:From the amino acid to the peptide. ACTA ACUST UNITED AC 2011. [DOI: 10.1088/1742-6596/261/1/012003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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12
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Reduction of protein radicals by GSH and ascorbate: potential biological significance. Amino Acids 2010; 39:1131-7. [DOI: 10.1007/s00726-010-0610-7] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Accepted: 04/23/2010] [Indexed: 01/02/2023]
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13
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The effect of neighboring methionine residue on tyrosine nitration and oxidation in peptides treated with MPO, H2O2, and NO2(-) or peroxynitrite and bicarbonate: role of intramolecular electron transfer mechanism? Arch Biochem Biophys 2008; 484:134-45. [PMID: 19056332 DOI: 10.1016/j.abb.2008.11.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 11/12/2008] [Accepted: 11/12/2008] [Indexed: 11/23/2022]
Abstract
Recent reports suggest that intramolecular electron transfer reactions can profoundly affect the site and specificity of tyrosyl nitration and oxidation in peptides and proteins. Here we investigated the effects of methionine on tyrosyl nitration and oxidation induced by myeloperoxidase (MPO), H2O2 and NO2(-) and peroxynitrite (ONOO(-)) or ONOO(-) and bicarbonate (HCO3(-)) in model peptides, tyrosylmethionine (YM), tyrosylphenylalanine (YF) and tyrosine. Nitration and oxidation products of these peptides were analyzed by HPLC with UV/Vis and fluorescence detection, and mass spectrometry; radical intermediates were identified by electron paramagnetic resonance (EPR)-spin-trapping. We have previously shown (Zhang et al., J. Biol. Chem. 280 (2005) 40684-40698) that oxidation and nitration of tyrosyl residue was inhibited in tyrosylcysteine(YC)-type peptides as compared to free tyrosine. Here we show that methionine, another sulfur-containing amino acid, does not inhibit nitration and oxidation of a neighboring tyrosine residue in the presence of ONOO(-) (or ONOOCO2(-)) or MPO/H2O2/NO2(-) system. Nitration of tyrosyl residue in YM was actually stimulated under the conditions of in situ generation of ONOO(-) (formed by reaction of superoxide with nitric oxide during SIN-1 decomposition), as compared to YF, YC and tyrosine. The dramatic variations in tyrosyl nitration profiles caused by methionine and cysteine residues have been attributed to differences in the direction of intramolecular electron transfer in these peptides. Further support for the interpretation was obtained by steady-state radiolysis and photolysis experiments. Potential implications of the intramolecular electron transfer mechanism in mediating selective nitration of protein tyrosyl groups are discussed.
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14
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Competitive photosensitized oxidation of tyrosine and methionine residues in enkephalins and their model peptides. J Photochem Photobiol A Chem 2008. [DOI: 10.1016/j.jphotochem.2008.02.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Zhang H, Xu Y, Joseph J, Kalyanaraman B. Influence of intramolecular electron transfer mechanism in biological nitration, nitrosation, and oxidation of redox-sensitive amino acids. Methods Enzymol 2008; 440:65-94. [PMID: 18423211 DOI: 10.1016/s0076-6879(07)00804-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
Using both high-performance liquid chromatography (HPLC) and electron spin resonance (ESR) spin-trappng techniques, we developed an analytical methodology for investigating intramolecular electron transfer-mediated tyrosyl nitration and cysteine nitrosation in model peptides. Peptides N-acetyl-TyrCys-amide (YC), N-acetyl-TyrAlaCys-amide, N-acetyl-TyrAlaAlaCys-amide, and N-acetyl-TyrAlaAlaAlaAlaCys-amide were used as models. Product analysis showed that nitration and oxidation products derived from YC and related peptides in the presence of myeloperoxidase (MPO)/H(2)O(2)/NO(2)(-) were not detectable. The major product was determined to be the corresponding disulfide (e.g., YCysCysY), suggestive of a rapid electron transfer from the tyrosyl radical to the cysteinyl residue. ESR spin-trapping experiments with 5,5'-dimethyl-1-pyrroline N-oxide (DMPO) demonstrated that thiyl radical intermediates were formed from peptides (e.g., YC) treated with MPO/H(2)O(2) and MPO/H(2)O(2)/NO(2)(-). Blocking the thiol group in YC totally abrogated thiyl radical formation. Under similar conditions, we were, however, able to trap the tyrosyl radical using the spin trap dibromonitrosobenzene sulfonic acid (DBNBS). Competition spin-trapping experiments revealed that intramolecular electron transfer is the dominant mechanism for thiyl radical formation in YC peptides. We conclude that a rapid intramolecular electron transfer mechanism between redox-sensitive amino acids could influence both protein nitration and nitrosation reactions. This mechanism brings together nitrative, nitrosative, and oxidative mechanisms in free radical biology.
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Affiliation(s)
- Hao Zhang
- Department of Biophysics and Free Radical Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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16
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Radiation chemistry of proteins. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s0167-6881(01)80022-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
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17
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Bobrowski K, Poznański J, Holcman J, Wierzchowski KL. Pulse Radiolysis Studies of Intramolecular Electron Transfer in Model Peptides and Proteins. 8. Trp[NH•+] → Tyr[O•] Radical Transformation in H-Trp-(Pro)n-Tyr-OH, n = 3−5, Series of Peptides. J Phys Chem B 1999. [DOI: 10.1021/jp992178h] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Krzysztof Bobrowski
- Institute of Nuclear Chemistry and Technology, 03-195 Warszawa, Poland, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warszawa, Poland, and Department of Environmental Sciences, Risø National Laboratory, DK-4000 Roskilde, Denmark
| | - Jaroslaw Poznański
- Institute of Nuclear Chemistry and Technology, 03-195 Warszawa, Poland, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warszawa, Poland, and Department of Environmental Sciences, Risø National Laboratory, DK-4000 Roskilde, Denmark
| | - Jerzy Holcman
- Institute of Nuclear Chemistry and Technology, 03-195 Warszawa, Poland, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warszawa, Poland, and Department of Environmental Sciences, Risø National Laboratory, DK-4000 Roskilde, Denmark
| | - Kazimierz L. Wierzchowski
- Institute of Nuclear Chemistry and Technology, 03-195 Warszawa, Poland, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warszawa, Poland, and Department of Environmental Sciences, Risø National Laboratory, DK-4000 Roskilde, Denmark
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Deterding LJ, Barr DP, Mason RP, Tomer KB. Characterization of cytochrome c free radical reactions with peptides by mass spectrometry. J Biol Chem 1998; 273:12863-9. [PMID: 9582316 DOI: 10.1074/jbc.273.21.12863] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The reactions of horse heart cytochrome c, hydrogen peroxide, and the spin trap 3,5-dibromo-4-nitrosobenzenesulfonic acid with a series of polypeptides were investigated using mass spectrometry. The mass spectra obtained from these reactions revealed that after a free radical has been generated on the heme-containing protein horse heart cytochrome c, it can be transferred to other biomolecules. In addition, the number of free radicals transferred to the target molecule could be determined. Recipient peptides/proteins that contained a tyrosine and/or tryptophan amino acid residue were most susceptible to free radical transfer. Using tandem mass spectrometry, the location of the 3,5-dibromo-4-nitrosobenzenesulfonic acid radical adduct on the nonapeptide RWIILGLNK was unequivocally determined to be at the tryptophan residue. We also demonstrated that the presence of an antioxidant in the reaction mixture not only inhibits free radical formation on horse heart cytochrome c, but also interferes with the transfer of the free radical, once it has been formed on cytochrome c.
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Affiliation(s)
- L J Deterding
- Laboratory of Structural Biology, NIEHS, Research Triangle Park, North Carolina 27709, USA
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19
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Chu Gao-Sheng, Yao Si-De, Zhang Zhi-Cheng, Wang Wen-Feng, Zhang Man-Wei. Intermolecular electron transfer involving phosphoryl and nonphosphoryl methionine and tryptophan, a pulse radiolysis study. Radiat Phys Chem Oxf Engl 1993 1997. [DOI: 10.1016/s0969-806x(97)00056-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Chu G, Yao S, Zhang Z, Zhang M, Wang W. pH effect of · OH radical induced oxidation of phosphorylmethionine in aqueous solution. CHINESE SCIENCE BULLETIN-CHINESE 1997. [DOI: 10.1007/bf02882464] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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Chaudhri SA, Mohan H, Anklam E, Asmus KD. Three-electron bonded σ/σ* radical cations from mixedly substituted dialkyl sulfides in aqueous solution studied by pulse radiolysis. ACTA ACUST UNITED AC 1996. [DOI: 10.1039/p29960000383] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Poznański J, Ejchart A, Wierzchowski KL, Ciurak M. 1H- and 13C-NMR investigations on cis-trans isomerization of proline peptide bonds and conformation of aromatic side chains in H-Trp-(Pro)n-Tyr-OH peptides. Biopolymers 1993; 33:781-95. [PMID: 8393714 DOI: 10.1002/bip.360330507] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
1H and 13C high-resolution nmr spectra of cationic, zwitterionic, and anionic forms of the peptides: H-Trp-(Pro)n-Tyr-OH, n = 0-5, and H-Trp-Pro-OCH3 were obtained in D2O solution. Analysis of H alpha (Pro1), H alpha (Trp), C gamma (Pro), H epsilon (Tyr), and H delta (Trp) resonances provided evidence for the presence of two predominant backbone isomers: the all-trans one and another with the Trp-Pro peptide bond in cis conformation; the latter constituted about 0.8 molar fraction of the total peptide (n > 1) concentration. Relative content of these isomers varied in a characteristic way with the number of Pro residues and the ionization state of the peptides. The highest content of the cis (Trp-Pro) isomer, 0.74, was found in the anionic form of H-Trp-Pro-Tyr-OH; it decreased in the order of: anion >> zwitterion approximately cation, and with the number of Pro residues to reach the value of 0.42 in the cationic form of H-Trp-(Pro)5-Tyr-OH. Isomerization equilibria about Pro-Pro bond(s) were found to be shifted far (> or = 0.9) in favor of the trans conformation. Interpretation of the measured vicinal coupling constants J alpha-beta' and J alpha-beta" for C alpha H-C beta H2 proton systems of Trp and Tyr side chains in terms of relative populations of g+, g-, and t staggered rotamers around the chi 1 dihedral angle indicated that in all the peptides studied (a) rotation of Trp indole ring in cis (Trp-Pro) isomers is strongly restricted, and (b) rotation of Tyr phenol ring is relatively free. The most preferred chi 1 rotamer of Trp (0.8-0.9 molar fraction) was assigned as the t one on the basis of a large value of the vicinal coupling constant between the high-field H beta and carbonyl carbon atoms of Trp, estimated for the cis (Pro1) form of H-Trp-Pro-Tyr-OH from a 1H, 13C correlated spectroscopy 1H-detected multiple quantum experiment. This indicates that cis<-->trans equilibrium in the Trp-Pro fragment is governed by nonbonding interactions between the pyrrolidine (Pro) and indole (Trp) rings. A molecular model of the terminal cis Trp-Pro dipeptide fragment is proposed, based on the presented nmr data and the results of our molecular mechanics modeling of low-energy conformers of the peptides, reported elsewhere.
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Affiliation(s)
- J Poznański
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warszawa
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