1
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Radomska K, Wolszczak M. Influence of Ionizing Radiation on Spontaneously Formed Aggregates in Proteins or Enzymes Solutions. Pharmaceutics 2023; 15:pharmaceutics15051367. [PMID: 37242609 DOI: 10.3390/pharmaceutics15051367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/21/2023] [Accepted: 04/25/2023] [Indexed: 05/28/2023] Open
Abstract
We have shown that many proteins and enzymes (ovalbumin, β-lactoglobulin, lysozyme, insulin, histone, papain) undergo concentration-dependent reversible aggregation as a result of the interaction of the studied biomolecules. Moreover, irradiation of those protein or enzyme solutions under oxidative stress conditions results in the formation of stable soluble protein aggregates. We assume that protein dimers are mainly formed. A pulse radiolysis study has been made to investigate the early stages of protein oxidation by N3• or •OH radicals. Reactions of the N3• radical with the studied proteins lead to the generation of aggregates stabilized by covalent bonds between tyrosine residues. The high reactivity of the •OH with amino acids contained within proteins is responsible for the formation of various covalent bonds (including C-C or C-O-C) between adjacent protein molecules. In the analysis of the formation of protein aggregates, intramolecular electron transfer from the tyrosine moiety to Trp• radical should be taken into account. Steady-state spectroscopic measurements with a detection of emission and absorbance, together with measurements of the dynamic scattering of laser light, made it possible to characterize the obtained aggregates. The identification of protein nanostructures generated by ionizing radiation using spectroscopic methods is difficult due to the spontaneous formation of protein aggregates before irradiation. The commonly used fluorescence detection of dityrosyl cross-linking (DT) as a marker of protein modification under the influence of ionizing radiation requires modification in the case of the tested objects. A precise photochemical lifetime measurement of the excited states of radiation-generated aggregates is useful in characterizing their structure. Resonance light scattering (RLS) has proven to be an extremely sensitive and useful technique to detect protein aggregates.
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Affiliation(s)
- Karolina Radomska
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, 93-590 Lodz, Poland
| | - Marian Wolszczak
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, 93-590 Lodz, Poland
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2
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Kielb PJ, Teutloff C, Bittl R, Gray HB, Winkler JR. Does Tyrosine Protect S. coelicolor Laccase from Oxidative Degradation or Act as an Extended Catalytic Site? J Phys Chem B 2022; 126:7943-7949. [PMID: 36191240 PMCID: PMC10231039 DOI: 10.1021/acs.jpcb.2c04835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have investigated the roles of tyrosine (Tyr) and tryptophan (Trp) residues in the four-electron reduction of oxygen catalyzed by Streptomyces coelicolor laccase (SLAC). During normal enzymatic turnover in laccases, reducing equivalents are delivered to a type 1 Cu center (CuT1) and then are transferred over 13 Å to a trinuclear Cu site (TNC: (CuT3)2CuT2) where O2 reduction occurs. The TNC in SLAC is surrounded by a large cluster of Tyr and Trp residues that can provide reducing equivalents when the normal flow of electrons is disrupted. Prior studies by Canters and co-workers [J. Am. Chem. Soc. 2009, 131 (33), 11680-11682] have shown that when O2 reacts with a reduced SLAC variant lacking the CuT1 center, a Tyr108• radical near the TNC forms rapidly. We have found that the Tyr108• radical is reduced 10 times faster than CuT12+ by excess ascorbate, possibly because of radical transfer along Tyr/Trp chains.
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Affiliation(s)
- Patrycja J. Kielb
- Beckman Institute, California Institute of Technology, Pasadena CA 91125, United States
| | | | - Robert Bittl
- Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Harry B. Gray
- Beckman Institute, California Institute of Technology, Pasadena CA 91125, United States
| | - Jay R. Winkler
- Beckman Institute, California Institute of Technology, Pasadena CA 91125, United States
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3
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Li H, Jiang G, Jia M, Cao S, Zhang S, Chen J, Sun H, Xu J, Knutson JR. Ultrafast Förster resonance energy transfer between tyrosine and tryptophan: potential contributions to protein-water dynamics measurements. Phys Chem Chem Phys 2022; 24:18055-18066. [PMID: 35861343 DOI: 10.1039/d2cp02139k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Ultrafast Förster Resonance Energy Transfer (FRET) between Tyrosine (Tyr, Y) and Tryptophan (Trp, W) in the model peptides Trp-(Pro)n-Tyr (WPnY) has been investigated using a femtosecond up-conversion spectrophotofluorometer. The ultrafast energy transfer process (<100 ps) in short peptides (WY, WPY and WP2Y) has been resolved. In fact, this FRET rate is found to be mixed with the rates of solvent relaxation (SR), ultrafast population decay (QSSQ) and other lifetime components. To further dissect and analyze the FRET, a spectral working model is constructed, and the contribution of a FRET lifetime is separated by reconciling the shapes of decay associated spectra (DAS). Surprisingly, FRET efficiency did not decrease monotonically with the growth of the peptide chain (as expected) but increased first and then decreased. The highest FRET efficiency occurred in peptide WPY. The kinetic results have been accompanied with molecular dynamics simulations that reconcile and explain this strange phenomenon: due to the strong interaction between amino acids, the distance between the donor and receptor in peptide WPY is actually closest, resulting in the fastest FRET. In addition, the FRET lifetimes (τcal) were estimated within the molecular dynamics simulations, and they were consistent with the lifetimes (τexp) separated out by the experimental measurements and the DAS working model. This benchmark study has implications for both previous and future studies of protein ultrafast dynamics. The approach taken can be generalized for the study of proximate tyrosine and tryptophan in proteins and it suggests spectral strategies for extracting mixed rates in other complex FRET problems.
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Affiliation(s)
- Haoyang Li
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
| | - Guanyu Jiang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
| | - Menghui Jia
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
| | - Simin Cao
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
| | - Sanjun Zhang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
| | - Jinquan Chen
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
| | - Haitao Sun
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
| | - Jianhua Xu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
| | - Jay R Knutson
- Laboratory of Advanced Microscopy & Biophotonics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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4
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Zhuravleva YS, Sherin PS. Influence of pH on radical reactions between kynurenic acid and amino acids tryptophan and tyrosine. Part II. Amino acids within the protein globule of lysozyme. Free Radic Biol Med 2021; 174:211-224. [PMID: 34363946 DOI: 10.1016/j.freeradbiomed.2021.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/29/2021] [Accepted: 08/01/2021] [Indexed: 12/20/2022]
Abstract
An acidosis, a decrease of pH within a living tissue, may alter yields of radical reactions if participating radicals undergo partial or complete protonation. One of photosensitizers found in the human eye lens, kynurenic acid (KNA-), possesses pKa 5.5 for its radical form that is close to physiological pH 6.89 for a healthy lens. In this work we studied the influence of pH on mechanisms and products of photoinduced radical reactions between KNA- and amino acids tryptophan (Trp) and tyrosine (Tyr) within a globule of model protein, Hen White Egg Lysozyme (HEWL). Our results show that the rate constant of back electron transfer from kynurenyl to HEWL• radicals with the restoration of initial reagents - the major decay pathway for these radicals - does not change in the pH 3-7. The quantum yield of HEWL degradation is also pH independent, however a shift of pH from 7 to 5 completely changes the outcome of photoinduced damage to HEWL from intermolecular cross-linking to oxygenation. HPLC-MS analysis has shown that four of six Trp and all Tyr residues of HEWL are modified in different extents at all pH, but the lowering of pH from 7 to 5 significantly changes the direction of main photodamage from Trp62 to Trp108 located at the entrance and bottom of enzymatic center, respectively. A decrease of intermolecular cross-links via Trp62 is followed by an increase in quantities of intramolecular cross-links Tyr20-Tyr23 and Tyr23-Tyr53. The obtained results point out the competence of cross-linking and oxygenation reactions for Trp and Tyr radicals within a protein globule and significant increase of oxygenation to the total damage of protein in the case of cross-linking deceleration by coulombic repulsion of positively charged protein globules.
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Affiliation(s)
- Yuliya S Zhuravleva
- International Tomography Center SB RAS, Institutskaya street 3a, Novosibirsk, Russia; Novosibirsk State University, Pirogova street 2, Novosibirsk, Russia
| | - Peter S Sherin
- International Tomography Center SB RAS, Institutskaya street 3a, Novosibirsk, Russia; Novosibirsk State University, Pirogova street 2, Novosibirsk, Russia.
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5
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Fuentes-Lemus E, Mariotti M, Hägglund P, Leinisch F, Fierro A, Silva E, Davies MJ, López-Alarcón C. Oxidation of lysozyme induced by peroxyl radicals involves amino acid modifications, loss of activity, and formation of specific crosslinks. Free Radic Biol Med 2021; 167:258-270. [PMID: 33731307 DOI: 10.1016/j.freeradbiomed.2021.03.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/05/2021] [Accepted: 03/06/2021] [Indexed: 12/21/2022]
Abstract
The present work examined the oxidation and crosslinking of the anti-bacterial enzyme lysozyme (Lyso), which is present in multiple biological fluids, and released from the cytoplasmic granules of macrophages and neutrophils at sites of infection and inflammation. It is therefore widely exposed to oxidants including peroxyl radicals (ROO•). We hypothesized that exposure to ROO• would generate specific modifications and inter- and intra-protein crosslinks via radical-radical reactions. Lyso was incubated with AAPH (2,2'-azobis(2-methylpropionamidine) dihydrochloride) as a ROO• source. Enzymatic activity was assessed, while oxidative modifications were detected and quantified using electrophoresis and liquid chromatography (UPLC) with fluorescence or mass detection (MS). Computational models of AAPH-Lyso interactions were developed. Exposure of Lyso to AAPH (10 and 100 mM for 3 h, and 20 mM for 1 h), at 37 °C, decreased enzymatic activity. 20 mM AAPH showed the highest efficiency of Lyso inactivation (1.78 mol of Lyso inactivated per ROO•). Conversion of Met to its sulfoxide, and to a lesser extent, Tyr oxidation to 3,4-dihydroxyphenylalanine and diTyr, were detected by UPLC-MS. Extensive transformation of Trp, involving short chain reactions, to kynurenine, oxindole, hydroxytryptophan, hydroperoxides or di-alcohols, and N-formyl-kynurenine was detected, with Trp62, Trp63 and Trp108 the most affected residues. Interactions of AAPH inside the negatively-charged catalytic pocket of Lyso, with Trp108, Asp52, and Glu35, suggest that Trp108 oxidation mediates, at least partly, Lyso inactivation. Crosslinks between Tyr20-Tyr23 (intra-molecular), and Trp62-Tyr23 (inter-molecular), were detected with both proximity (Tyr20-Tyr23), and chain flexibility (Trp62) appearing to favor the formation of covalent crosslinks.
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Affiliation(s)
| | - Michele Mariotti
- University of Copenhagen, Department of Biomedical Sciences, Copenhagen, Denmark
| | - Per Hägglund
- University of Copenhagen, Department of Biomedical Sciences, Copenhagen, Denmark
| | - Fabian Leinisch
- University of Copenhagen, Department of Biomedical Sciences, Copenhagen, Denmark
| | - Angélica Fierro
- Pontificia Universidad Católica de Chile(,) Facultad de Química y de Farmacia, Departamento de Química Orgánica, Santiago, Chile
| | - Eduardo Silva
- Pontificia Universidad Católica de Chile, Facultad de Química y de Farmacia, Departamento de Química Física, Santiago, Chile
| | - Michael J Davies
- University of Copenhagen, Department of Biomedical Sciences, Copenhagen, Denmark.
| | - Camilo López-Alarcón
- Pontificia Universidad Católica de Chile, Facultad de Química y de Farmacia, Departamento de Química Física, Santiago, Chile.
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6
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Zhao J, Zhu R, Zhang X, Zhang B, Liu Y, Li Y, Wang W, Phillips DL. A photoenhanced oxidation of amino acids and the cross-linking of lysozyme mediated by tetrazolium salts. Phys Chem Chem Phys 2021; 23:3761-3770. [PMID: 33538741 DOI: 10.1039/d0cp04887a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tetrazolium salts (TZs) are pervasively utilized as precursors in the dye industry, colorimetric probes in enzyme assays and for exploring nanomaterial toxicity, but its own toxicity is not investigated enough so far. Using femtosecond transient absorption spectroscopy, nanosecond pulse radiolysis (ns-PRL), western blotting and UV-vis absorption spectroscopy, here we characterized a neutral tetrazolinyl radical (with the same maximum absorption at 420 nm and different lifetimes of 5.0 and 9.0 μs for two selected TZs), the key intermediate of TZs reduction, and noticed TZs-formazan production under UV light irradiation accompanied by 41% increase in the cross-linking of lysozyme (Lyso, model protein) compared to TZs-free sample, which uncovered the photoenhanced oxidation of TZs towards Lyso. The ns-PRL in a reductive atmosphere simulated the electron/proton donors of amino acid residues in Lyso upon photoexcitation and revealed the reduction mechanism of TZs, as that first followed one-electron-transfer and then probably proton-coupled electron transfer. This is the first time to report on the photoenhanced oxidation mechanism of TZs, which would provide new insights into the applications of TZs in cell biology, "click" chemistry and nanotoxicology.
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Affiliation(s)
- Jianfeng Zhao
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong 11111, P. R. China
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7
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Savina ED, Tsentalovich YP, Sherin PS. UV-A induced damage to lysozyme via Type I photochemical reactions sensitized by kynurenic acid. Free Radic Biol Med 2020; 152:482-493. [PMID: 31751763 DOI: 10.1016/j.freeradbiomed.2019.11.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/12/2019] [Accepted: 11/13/2019] [Indexed: 02/06/2023]
Abstract
In this work we studied the mechanisms of Type I photodamage to a model protein, hen egg white lysozyme (HEWL), sensitized by kynurenic acid (KNA) - one of the most efficient photosensitizers of the human eye lens present in trace amounts within tissue. The kynurenic acid radical, KNA•-, formed in the quenching of triplet KNA by HEWL, can be readily oxidized by molecular oxygen with the formation of superoxide anion radical O2•-. This leads to two ways of damage to proteins: either via the direct reactions between KNA•- and HEWL• radicals (Type Ia) or via the reactions between superoxide anion O2•- and HEWL• radicals (Type Ib). Our results demonstrate significant degradation of the protein during Type Ia photolysis with the formation of various oligomeric and oxygenated forms of HEWL and several deoxygenated products of KNA. Liquid chromatography-mass spectrometry analysis revealed the cross-linking of HEWL via tryptophan (Trp62) and tyrosine (Tyr23) residues and, for the first time, the covalent binding of KNA to protein via tryptophan (Trp62 and Trp123) residues. It was found that Type Ib reactions lead to substantially smaller damage to HEWL; the degradation quantum yields (Φdeg) of HEWL are 1.3 ± 0.3% and 0.12 ± 0.03% for Type Ia and Ib photolyses, respectively. Low Φdeg values for both types of photolysis indicate the Back Electron Transfer (BET) with the restoration of initial reagents as the main radical decay path with significantly higher BET efficiency in the case of Type Ib reactions. Therefore, in essentially oxygen-free tissues like the eye lens, the direct radical reactions via Type Ia mechanism could induce significantly larger damage to proteins, leading to their cross-linking and oxidation. The accumulation of these modifications can cause the development of various diseases, in particular, cataracts in the eye lens.
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Affiliation(s)
- Ekaterina D Savina
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090, Novosibirsk, Russia; Novosibirsk State University, Pirogova str. 2, 630090, Novosibirsk, Russia
| | - Yuri P Tsentalovich
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090, Novosibirsk, Russia; Novosibirsk State University, Pirogova str. 2, 630090, Novosibirsk, Russia
| | - Peter S Sherin
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090, Novosibirsk, Russia; Novosibirsk State University, Pirogova str. 2, 630090, Novosibirsk, Russia.
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8
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Mahmoudi L, Kissner R, Nauser T, Koppenol WH. Electrode Potentials of l-Tryptophan, l-Tyrosine, 3-Nitro-l-tyrosine, 2,3-Difluoro-l-tyrosine, and 2,3,5-Trifluoro-l-tyrosine. Biochemistry 2016; 55:2849-56. [DOI: 10.1021/acs.biochem.6b00019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Leila Mahmoudi
- Institute of Inorganic Chemistry,
Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich CH-8093, Switzerland
| | - Reinhard Kissner
- Institute of Inorganic Chemistry,
Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich CH-8093, Switzerland
| | - Thomas Nauser
- Institute of Inorganic Chemistry,
Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich CH-8093, Switzerland
| | - Willem H. Koppenol
- Institute of Inorganic Chemistry,
Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich CH-8093, Switzerland
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9
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Gangele K, Poluri KM. Imidazole derivatives differentially destabilize the low pH conformation of lysozyme through weak electrostatic interactions. RSC Adv 2016. [DOI: 10.1039/c6ra23031h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Imidazole derivatives forms charge transfer complexes with lysozyme at low pH (4–2) and destabilize its conformation through weak electrostatic interactions.
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Affiliation(s)
- Krishnakant Gangele
- Department of Biotechnology
- Indian Institute of Technology Roorkee
- Roorkee – 247667
- India
| | - Krishna Mohan Poluri
- Department of Biotechnology
- Indian Institute of Technology Roorkee
- Roorkee – 247667
- India
- Centre for Nanotechnology
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10
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Et Taouil A, Brun E, Duchambon P, Blouquit Y, Gilles M, Maisonhaute E, Sicard-Roselli C. How protein structure affects redox reactivity: example of Human centrin 2. Phys Chem Chem Phys 2014; 16:24493-8. [DOI: 10.1039/c4cp03536d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Human centrin 2 is a protein very sensitive to oxidative stress. Protein reactivity is unraveled by gamma radiolysis and electrochemical techniques.
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Affiliation(s)
- Abdeslam Et Taouil
- Sorbonne Universités
- UPMC Univ Paris 06
- UMR 8235
- Laboratoire Interfaces et Systèmes Electrochimiques
- Paris, France
| | - Emilie Brun
- Laboratoire de Chimie Physique
- CNRS UMR 8000
- Université Paris-Sud
- Bât. 350
- 91405 Orsay Cedex, France
| | - Patricia Duchambon
- Plateforme Production Protéines Recombinantes
- Institut Curie-INSERM U759
- Université Paris-Sud
- 91405 Orsay Cedex, France
| | - Yves Blouquit
- Institut Curie-INSERM U759
- Université Paris-Sud
- 91405 Orsay Cedex, France
| | - Manon Gilles
- Laboratoire de Chimie Physique
- CNRS UMR 8000
- Université Paris-Sud
- Bât. 350
- 91405 Orsay Cedex, France
| | - Emmanuel Maisonhaute
- Sorbonne Universités
- UPMC Univ Paris 06
- UMR 8235
- Laboratoire Interfaces et Systèmes Electrochimiques
- Paris, France
| | - Cécile Sicard-Roselli
- Laboratoire de Chimie Physique
- CNRS UMR 8000
- Université Paris-Sud
- Bât. 350
- 91405 Orsay Cedex, France
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11
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Morlière P, Mazière JC, Patterson LK, Conte MA, Dupas JL, Ducroix JP, Filipe P, Santus R. On the repair of oxidative damage to apoferritin: a model study with the flavonoids quercetin and rutin in aerated and deaerated solutions. Free Radic Res 2013; 47:463-73. [DOI: 10.3109/10715762.2013.791024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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12
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Pattison DI, Lam M, Shinde SS, Anderson RF, Davies MJ. The nitroxide TEMPO is an efficient scavenger of protein radicals: cellular and kinetic studies. Free Radic Biol Med 2012; 53:1664-74. [PMID: 22974763 DOI: 10.1016/j.freeradbiomed.2012.08.578] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 08/10/2012] [Accepted: 08/20/2012] [Indexed: 11/18/2022]
Abstract
Protein oxidation occurs during multiple human pathologies, and protein radicals are known to induce damage to other cell components. Such damage may be modulated by agents that scavenge protein radicals. In this study, the potential protective reactions of the nitroxide TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxyl radical) against Tyr- and Trp-derived radicals (TyrO./TrpN.) have been investigated. Pretreatment of macrophage cells with TEMPO provided protection against photo-oxidation-induced loss of cell viability and Tyr oxidation, with the nitroxide more effective than the hydroxylamine or parent amine. Pulse radiolysis was employed to determine rate constants, k, for the reaction of TEMPO with TyrO. and TrpN. generated on N-Ac-Tyr-amide and N-Ac-Trp-amide, with values of k~10(8) and 7×10(6)M(-1)s(-1), respectively, determined. Analogous studies with lysozyme, chymotrypsin, and pepsin yielded k for TEMPO reacting with TrpN. ranging from 1.5×10(7) (lysozyme) to 1.1×10(8) (pepsin)M(-1)s(-1). Pepsin-derived TyrO. reacted with TEMPO with k~4×10(7)M(-1)s(-1); analogous reactions for lysozyme and chymotrypsin TyrO. were much slower. These data indicate that TEMPO can inhibit secondary reactions of both TyrO. and TrpN., though this is protein dependent. Such protein radical scavenging may contribute to the positive biological effects of nitroxides.
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13
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Lee M, Urata SM, Aguilera JA, Perry CC, Milligan JR. Modeling the Influence of Histone Proteins on the Sensitivity of DNA to Ionizing Radiation. Radiat Res 2012; 177:152-63. [DOI: 10.1667/rr2812.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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14
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Patterson LK, Mazière JC, Bartels DM, Hug GL, Santus R, Morlière P. Evidence for a slow and oxygen-insensitive intra-molecular long range electron transfer from tyrosine residues to the semi-oxidized tryptophan 214 in human serum albumin: its inhibition by bound copper (II). Amino Acids 2010; 42:1269-75. [DOI: 10.1007/s00726-010-0819-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 11/22/2010] [Indexed: 11/29/2022]
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15
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Joshi R, Mukherjee T. Effect of ionic micellar medium on kinetics and mechanism of oxidation of bovine serum albumin: A pulse radiolysis study. Radiat Phys Chem Oxf Engl 1993 2010. [DOI: 10.1016/j.radphyschem.2010.04.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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16
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Wang ZY, Zhang ZC, Zhang MW, Yao SD, Luo J, Wang WF, Zhang JS, Lin NY. Electron transfer in phosphorylated peptide-Study of laser photolysis on N-dipp-TrpH-TyrOH peptide. CHINESE J CHEM 2010. [DOI: 10.1002/cjoc.19950130407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Chen X, Zhang L, Zhang L, Wang J, Liu H, Bu Y. Proton-Regulated Electron Transfers from Tyrosine to Tryptophan in Proteins: Through-Bond Mechanism versus Long-Range Hopping Mechanism. J Phys Chem B 2009; 113:16681-8. [DOI: 10.1021/jp9077689] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Xiaohua Chen
- Center for Modeling & Simulation Chemistry, Institute of Theoretical Chemistry, Shandong University, Jinan 250100, P. R. China
| | - Laibin Zhang
- Center for Modeling & Simulation Chemistry, Institute of Theoretical Chemistry, Shandong University, Jinan 250100, P. R. China
| | - Liang Zhang
- Center for Modeling & Simulation Chemistry, Institute of Theoretical Chemistry, Shandong University, Jinan 250100, P. R. China
| | - Jun Wang
- Center for Modeling & Simulation Chemistry, Institute of Theoretical Chemistry, Shandong University, Jinan 250100, P. R. China
| | - Haiying Liu
- Center for Modeling & Simulation Chemistry, Institute of Theoretical Chemistry, Shandong University, Jinan 250100, P. R. China
| | - Yuxiang Bu
- Center for Modeling & Simulation Chemistry, Institute of Theoretical Chemistry, Shandong University, Jinan 250100, P. R. China
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18
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Blouquit Y, Duchambon P, Brun E, Marco S, Rusconi F, Sicard-Roselli C. High sensitivity of human centrin 2 toward radiolytical oxidation: C-terminal tyrosinyl residue as the main target. Free Radic Biol Med 2007; 43:216-28. [PMID: 17603931 DOI: 10.1016/j.freeradbiomed.2007.04.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Revised: 03/27/2007] [Accepted: 04/02/2007] [Indexed: 11/15/2022]
Abstract
Centrins are calcium-binding proteins that play a significant role in the maintenance of the centrosomal organization, mainly in the continuity between centrosome and microtubular network. Recent data showed that centrosome duplication abnormalities, like overduplication for example, could be due to hydrogen peroxide, suggesting an important impact of oxidative stress. To challenge this hypothesis, we performed one-electron oxidation experiments with human centrin 2, starting from azide radicals. Our results first revealed several intermolecular cross-links generating dimers, tetramers, hexamers, and higher molecular mass species. Dimers result from covalent bond linking the C-terminal tyrosines of each monomer. Second, the methionyl residue at position 19 was oxidized on the monomeric centrin. Further, electron microscopy experiments on centrin 2 showed a preexisting hexameric organization that was stabilized by covalent bonds as a result of irradiation. Overall, these results show that centrin 2 is highly sensitive to ionizing radiation, which could have important consequences on its biological functions.
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Affiliation(s)
- Yves Blouquit
- INSERM U759, Imagerie Intégrative, Campus Universitaire d'Orsay, Bât. 112, 91405 Orsay Cedex, France
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19
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20
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Abstract
Current studies provide evidence that proteins are initial targets of ROS (reactive oxygen species) in biological systems and that the damaged proteins can in turn damage other cell constituents. This study was designed to test the possibility that protein radicals generated by ROS can oxidize GSH and assess the probability of this reaction in vivo by measurement of the rate constant of this reaction. Lysozyme radicals were generated by hydroxyl and azide radicals in steady-state gamma ray radiolysis. In the absence of dioxygen, a range of protein carbon-centred amino acid radicals were produced by the hydroxyl radicals, and defined tryptophan radicals by the azide radicals. In the presence of dioxygen, each carbon-centred radical was converted to a protein peroxyl radical. Each of the peroxyl radicals was able to oxidize a molecule of GSH, regardless of its location in the protein. The peroxyl radicals were 10 and 20 times more effective GSH oxidants than the carbon-centred radicals produced randomly in the lysozyme, or the defined tryptophan lysozyme radicals respectively. We obtained for the first time the rate constant of reaction between a protein free-radical and GSH. Lysozyme tryptophan carbon radicals generated by nanosecond pulse radiolysis and flash photolysis oxidized GSH with a rate constant of (1.05+/-0.05)x10(5) M(-1) x s(-1). Overall, the results are consistent with the hypothesis that protein radicals may be important intermediates in the pathway linking oxidative stress and damage in living organisms and emphasize the strongly enhancing role of dioxygen in this process.
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Affiliation(s)
- Thomas Nauser
- *Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Willem H. Koppenol
- *Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Janusz M. Gebicki
- †Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109, Australia
- To whom correspondence should be addressed (email )
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21
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Goldstein S, Samuni A. Intra- and intermolecular oxidation of oxymyoglobin and oxyhemoglobin induced by hydroxyl and carbonate radicals. Free Radic Biol Med 2005; 39:511-9. [PMID: 16043022 DOI: 10.1016/j.freeradbiomed.2005.04.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2005] [Revised: 04/03/2005] [Accepted: 04/04/2005] [Indexed: 10/25/2022]
Abstract
The mechanism of the reactions of myoglobin and hemoglobin with *OH and CO3*- in the presence of oxygen was studied using pulse and gamma-radiolysis. Unlike *NO2, which adds to the porphyrin iron, *OH and CO3*- form globin radicals. These secondary radicals oxidize the Fe(II) center through both intra- and intermolecular processes. The intermolecular pathway was further demonstrated when BSA radicals derived from *OH or CO3*- oxidized oxyhemoglobin and oxymyoglobin to their respective ferric states. The oxidation yields obtained by pulse radiolysis were lower compared to gamma-radiolysis, where the contribution of radical-radical reactions is negligible. Full oxidation yields by *OH-derived globin radicals could be achieved only at relatively high concentrations of the heme protein mainly via an intermolecular pathway. It is suggested that CO3*- reaction with the protein yields Tyr and/or Trp-derived phenoxyl radicals, which solely oxidize the porphyrin iron under gamma-radiolysis conditions. The *OH particularly adds to aromatic residues, which can undergo elimination of H2O forming the phenoxyl radical, and/or react rapidly with O2 yielding peroxyl radicals. The peroxyl radical can oxidize a neighboring porphyrin iron and/or give rise to superoxide, which neither oxidize nor reduce the porphyrin iron. The potential physiological implications of this chemistry are that hemoglobin and myoglobin, being present at relatively high concentrations, can detoxify highly oxidizing radicals yielding the respective ferric states, which are not toxic.
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Affiliation(s)
- Sara Goldstein
- Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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22
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Reece SY, Stubbe J, Nocera DG. pH Dependence of charge transfer between tryptophan and tyrosine in dipeptides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1706:232-8. [PMID: 15694351 DOI: 10.1016/j.bbabio.2004.11.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Revised: 11/11/2004] [Accepted: 11/15/2004] [Indexed: 11/20/2022]
Abstract
Time-resolved absorption spectroscopy has been employed to study the directionality and rate of charge transfer in W-Y and Ac-W-Y dipeptides as a function of pH. Excitation with 266-nm nanosecond laser pulses produces both W (or [WH](+), depending on pH) and Y. Between pH 6 and 10, W to was found to oxidize Y with k(X)=9.0x10(4) s(-1) and 1.8x10(4) s(-1) for the W-Y and Ac-W-Y dipeptide systems, respectively. The intramolecular charge transfer rate increases as the pH is lowered over the range 6>pH>2. For 10<pH<12, the rate of radical transport for the W-Y dipeptide decreases and becomes convoluted with other radical decay processes, the timescales of which have been identified in studies of control dipeptides Ac-F-Y and W-F. Further increases in pH prompt the reverse reaction to occur, W-Y-->W-Y(-) (Y(-), tyrosinate anion), with a rate constant of k(X)=1.2x10(5) s(-1). The dependence of charge transfer directionality between W and Y on pH is important to the enzymatic function of several model and natural biological systems as discussed here for ribonucleotide reductase.
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Affiliation(s)
- Steven Y Reece
- Department of Chemistry, 6-335, 77 Massachusetts Avenue, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA
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23
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Sicard-Roselli C, Lemaire S, Jacquot JP, Favaudon V, Marchand C, Houée-Levin C. Thioredoxin Ch1 of Chlamydomonas reinhardtii displays an unusual resistance toward one-electron oxidation. ACTA ACUST UNITED AC 2004; 271:3481-7. [PMID: 15317583 DOI: 10.1111/j.1432-1033.2004.04279.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
To test thioredoxin resistance to oxidizing free radicals, we have studied the one-electron oxidation of wild-type thioredoxin and of two forms with the point mutations D30A and W35A, using azide radicals generated by gamma-ray or pulse radiolysis. The oxidation patterns of wild-type thioredoxin and D30A are similar. In these forms, Trp35 is the primary target and is 'repaired' by one-electron reduction; first by intramolecular electron transfer from tyrosine, and then from other residues. Conversely, during oxidation of W35A, Trp13 is poorly reactive. For all proteins, activity is conserved showing an unusual resistance toward oxidation.
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24
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Gunther MR. Probing the free radicals formed in the metmyoglobin-hydrogen peroxide reaction. Free Radic Biol Med 2004; 36:1345-54. [PMID: 15135170 DOI: 10.1016/j.freeradbiomed.2004.02.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2003] [Revised: 02/09/2004] [Accepted: 02/13/2004] [Indexed: 01/13/2023]
Abstract
The reaction between metmyoglobin and hydrogen peroxide results in the two-electron reduction of H2O2 by the protein, with concomitant formation of a ferryl-oxo heme and a protein-centered free radical. Sperm whale metmyoglobin, which contains three tyrosine residues (Tyr-103, Tyr-146, and Tyr-151) and two tryptophan residues (Trp-7 and Trp-14), forms a tryptophanyl radical at residue 14 that reacts with O2 to form a peroxyl radical and also forms distinct tyrosyl radicals at Tyr-103 and Tyr-151. Horse metmyoglobin, which lacks Tyr-151 of the sperm whale protein, forms an oxygen-reactive tryptophanyl radical and also a phenoxyl radical at Tyr-103. Human metmyoglobin, in addition to the tyrosine and tryptophan radicals formed on horse metmyoglobin, also forms a Cys-110-centered thiyl radical that can also form a peroxyl radical. The tryptophanyl radicals react both with molecular oxygen and with the spin trap 3,5-dibromo-4-nitrosobenzenesulfonic acid (DBNBS). The spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) traps the Tyr-103 radicals and the Cys-110 thiyl radical of human myoglobin, and 2-methyl-2-nitrosopropane (MNP) traps all of the tyrosyl radicals. When excess H2O2 is used, DBNBS traps only a tyrosyl radical on horse myoglobin, but the detection of peroxyl radicals and the loss of tryptophan fluorescence support tryptophan oxidation under those conditions. Kinetic analysis of the formation of the various free radicals suggests that tryptophanyl radical and tyrosyl radical formation are independent events, and that formation of the Cys-110 thiyl radical on human myoglobin occurs via oxidation of the thiol group by the Tyr-103 phenoxyl radical. Peptide mapping studies of the radical adducts and direct EPR studies at low temperature and room temperature support the conclusions of the EPR spin trapping studies.
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Affiliation(s)
- Michael R Gunther
- Department of Biochemistry and Molecular Pharmacology, West Virginia University, Morgantown, WV 26505, USA.
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25
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Stuart-Audette M, Blouquit Y, Faraggi M, Sicard-Roselli C, Houée-Levin C, Jollès P. Re-evaluation of intramolecular long-range electron transfer between tyrosine and tryptophan in lysozymes. Evidence for the participation of other residues. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:3565-71. [PMID: 12919320 DOI: 10.1046/j.1432-1033.2003.03741.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
One-electron oxidation of six different c-type lysozymes from hen egg white, turkey egg white, human milk, horse milk, camel stomach and tortoise was studied by gamma- and pulse-radiolysis. In the first step, one tryptophan side chain is oxidized to indolyl free radical, which is produced quantitatively. As shown already, the indolyl radical subsequently oxidizes a tyrosine side chain to the phenoxy radical in an intramolecular reaction. However this reaction is not total and its stoichiometry depends on the protein. Rate constants also vary between proteins, from 120 x s(-1) to 1000 x s(-1) at pH 7.0 and room temperature [extremes are hen and turkey egg white (120 x s(-1)) and human milk (1000 x s(-1))]. In hen and turkey egg white lysozymes we show that another reactive site is the Asn103-Gly104 peptidic bond, which gets broken radiolytically. Tryptic digestion followed by HPLC separation and identification of the peptides was performed for nonirradiated and irradiated hen lysozyme. Fluorescence spectra of the peptides indicate that Trp108 and/or 111 remain oxidized and that Tyr20 and 53 give bityrosine. Tyr23 appears not to be involved in the process. Thus new features of long-range intramolecular electron transfer in proteins appear: it is only partial and other groups are involved which are silent in pulse radiolysis.
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26
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Durchschlag H, Hefferle T, Zipper P. Comparative investigations of the effects of X- and UV-irradiation on lysozyme in the absence or presence of additives. Radiat Phys Chem Oxf Engl 1993 2003. [DOI: 10.1016/s0969-806x(03)00089-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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27
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Joshi R, Mukherjee T. Effect of solvent viscosity, polarity and pH on the charge transfer between tryptophan radical and tyrosine in bovine serum albumin: a pulse radiolysis study. Biophys Chem 2003; 103:89-98. [PMID: 12504257 DOI: 10.1016/s0301-4622(02)00234-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The effect of viscosity, solvent polarity and pH of the medium on the reaction of a protein, bovine serum albumin (BSA), with organohalo-peroxyl radical in aqueous solution has been studied using pulse radiolysis technique. Unlike in dilute aqueous solution, electron transfer from tyrosine to tryptophan radical in BSA has been clearly observed at a viscosity of 7.7 centiPoise (cP). The oxidation of BSA, tryptophan and tyrosine in different media has also been compared with those taking place in dilute aqueous solution. The effect of solvent characteristics on the observed charge transfer has been discussed.
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Affiliation(s)
- R Joshi
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
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28
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Filipe P, Morlière P, Patterson LK, Hug GL, Mazière JC, Mazière C, Freitas JP, Fernandes A, Santus R. Repair of amino acid radicals of apolipoprotein B100 of low-density lipoproteins by flavonoids. A pulse radiolysis study with quercetin and rutin. Biochemistry 2002; 41:11057-64. [PMID: 12206678 DOI: 10.1021/bi026133+] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Selective oxidative damage to apolipoprotein B in LDL can be effected radiolytically by (*)Br(2)(-) radicals. Twenty-seven Trp residues constitute major primary sites of oxidation, but two-thirds of oxidized Trps ((*)Trp) that are formed are repaired by intramolecular electron transfer from Tyr residues with formation of phenoxyl radicals (TyrO(*)). Analysis of (*)Trp and TyrO(*) transient absorbance changes suggests that other apolipoprotein B residues, probably Cys, are oxidized. LDL-bound quercetin can efficiently repair this damage. Absorption studies show that a LDL particle has the capacity to bind approximately 10 quercetin molecules through interaction with apolipoprotein B. The repair occurs by intramolecular electron transfer characterized by a rate constant of 2 x 10(3) s(-)(1). In contrast, rutin, a related flavonoid which does not bind to LDL, cannot repair oxidized apolipoprotein B. Urate is a hydrophilic plasma antioxidant which displays synergistic antioxidant properties with flavonoids. Urate radicals produced by (*)Br(2)(-) can also be repaired by LDL-bound quercetin. This repair occurs with a reaction rate constant of 6.8 x 10(7) M(-)(1) s(-)(1). Comparison with previous studies conducted with human serum albumin-bound quercetin suggests that quercetin analogues tailored to be carried preferentially by lipoproteins might be more powerful plasma antioxidants than natural quercetin carried by serum albumin.
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Affiliation(s)
- Paulo Filipe
- Centro de Metabolismo e Endocrinologia da Faculdade de Medicina de Lisboa, 1649-028 Lisboa, Portugal
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29
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Filipe P, Morlière P, Patterson LK, Hug GL, Mazière JC, Mazière C, Freitas JP, Fernandes A, Santus R. Mechanisms of flavonoid repair reactions with amino acid radicals in models of biological systems: a pulse radiolysis study in micelles and human serum albumin. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1572:150-62. [PMID: 12204344 DOI: 10.1016/s0304-4165(02)00302-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Neutral tryptophan (*Trp) and tyrosine (TyrO(*)) radicals are repaired by certain flavonoids in buffer, in micelles and in human serum albumin (HSA) with corresponding formation of semioxidized flavonoid radicals. In deaerated buffer, *Trp but not TyrO(*) radicals react with catechin. In micelles, quercetin and rutin repair both *Trp and TyrO(*) radicals. In addition to amino acid reactivity, microenvironmental factors and nature of the flavonoids govern this repair. Electron transfer efficiencies from quercetin to negatively charged *Trp radicals are 100% in the micellar pseudophases of positively charged cetyltrimethylammonium bromide, (CTAB), and neutral Triton X100 (TX100), but 55% in negatively charged sodium dodecyl sulfate (SDS). In oxygen-saturated CTAB micelles, quercetin also reacts with the superoxide radical anion. When bound to domain IIA of HSA, quercetin repairs, by intra- or intermolecular encounter, less than 20% of oxidative damage to HSA. Quercetin can also repair freely circulating oxidized molecules with repair efficiencies falling to 7% for oxidized Trp, Tyr and alpha-MSH and to less than 2% for urate radical. This limited effectiveness is attributed both to the inaccessibility of bound quercetin and rutin toward radicals of circulating molecules and to the diffusion-controlled recombination of these radicals.
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Affiliation(s)
- Paulo Filipe
- Centro de Metabolismo e Endocrinologia da Faculdade de Medicina de Lisboa, 1699 Lisbon, Portugal
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30
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Filipe P, Morlière P, Patterson LK, Hug GL, Mazière JC, Mazière C, Freitas JP, Fernandes A, Santus R. Mechanisms of flavonoid repair reactions with amino acid radicals in models of biological systems: a pulse radiolysis study in micelles and human serum albumin. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1571:102-14. [PMID: 12049790 DOI: 10.1016/s0304-4165(02)00188-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Neutral tryptophan (*Trp) and tyrosine (TyrO(*)) radicals are repaired by certain flavonoids in buffer, in micelles and in human serum albumin (HSA) with corresponding formation of semioxidized flavonoid radicals. In deaerated buffer, *Trp but not TyrO(*) radicals react with catechin. In micelles, quercetin and rutin repair both *Trp and TyrO(*) radicals. In addition to amino acid reactivity, microenvironmental factors and nature of the flavonoids govern this repair. Electron transfer efficiencies from quercetin to negatively charged *Trp radicals are 100% in the micellar pseudophases of positively charged cetyltrimethylammonium bromide, (CTAB), and neutral Triton X100 (TX100), but 55% in negatively charged sodium dodecyl sulfate (SDS). In oxygen-saturated CTAB micelles, quercetin also reacts with the superoxide radical anion. When bound to domain IIA of HSA, quercetin repairs, by intra- or intermolecular encounter, less than 20% of oxidative damage to HSA. Quercetin can also repair freely circulating oxidized molecules with repair efficiencies falling to 7% for oxidized *Trp, Tyr and alpha-MSH and to less than 2% for urate radical. This limited effectiveness is attributed both to the inaccessibility of bound quercetin and rutin toward radicals of circulating molecules and to the diffusion-controlled recombination of these radicals.
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Affiliation(s)
- Paulo Filipe
- Centro de Metabolismo e Endocrinologia da Faculdade de Medicina de Lisboa, Portugal
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31
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Joshi R, Mukherjee T. Charge transfer between tryptophan and tyrosine in casein: a pulse radiolysis study. Biophys Chem 2002; 96:15-9. [PMID: 11975990 DOI: 10.1016/s0301-4622(02)00032-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Charge transfer from tyrosine to tryptophan radicals in bovine milk casein, as observed using pulse radiolysis technique, is reported. The reactions of casein with hydroxyl, azide, Br(2)(*-) and CCl(3)O(2)(*) radicals have also been studied. Radical transformation was found to take place at a rate of 1.5 x10(4) s(-1). The effect of pH, oxidising radical and the proximity of tyrosine and tryptophan on this radical transformation, as well as repair of the casein radical by ascorbate, have also been studied.
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Affiliation(s)
- Ravi Joshi
- Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
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32
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Ababou A, Bombarda E. On the involvement of electron transfer reactions in the fluorescence decay kinetics heterogeneity of proteins. Protein Sci 2001; 10:2102-13. [PMID: 11567101 PMCID: PMC2374218 DOI: 10.1110/ps.05501] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Time-resolved fluorescence study of single tryptophan-containing proteins, nuclease, ribonuclease T1, protein G, glucagon, and mastoparan, has been carried out. Three different methods were used for the analysis of fluorescence decays: the iterative reconvolution method, as reviewed and developed in our laboratory, the maximum entropy method, and the recent method that we called "energy transfer" method. All the proteins show heterogeneous fluorescence kinetics (multiexponential decay). The origin of this heterogeneity is interpreted in terms of current theories of electron transfer process, which treat the electron transfer process as a radiationless transition. The theoretical electron transfer rate was calculated assuming the peptide bond carbonyl as the acceptor site. The good agreement between experimental and theoretical electron-transfer rates leads us to suggest that the electron-transfer process is the principal quenching mechanism of Trp fluorescence in proteins, resulting in heterogeneous fluorescence kinetics. Furthermore, the origin of apparent homogeneous fluorescence kinetics (monoexponential decay) in some proteins also can be explained on the basis of electron-transfer mechanism.
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Affiliation(s)
- A Ababou
- Pharmacologie et Physico-Chimie des Interactions Cellulaires et Moléculaires, UMR 7034 CNRS, Université Louis Pasteur, Strasbourg 1, Illkirch, France.
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33
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Diederix RE, Ubbink M, Canters GW. The peroxidase activity of cytochrome c-550 from Paracoccus versutus. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:4207-16. [PMID: 11488914 DOI: 10.1046/j.1432-1327.2001.02335.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Next to their natural electron transport capacities, c-type cytochromes possess low peroxidase and cytochrome P-450 activities in the presence of hydrogen peroxide. These catalytic properties, in combination with their structural robustness and covalently bound cofactor make cytochromes c potentially useful peroxidase mimics. This study reports on the peroxidase activity of cytochrome c-550 from Paracoccus versutus and the loss of this activity in presence of H2O2. The rate-determining step in the peroxidase reaction of cytochrome c-550 is the formation of a reactive intermediate, following binding of peroxide to the haem iron. The reaction rate is very low compared to horseradish peroxidase (approximately one millionth), because of the poor accessibility of the haem iron for H2O2, and the lack of a base catalyst such as the distal His of the peroxidases. This is corroborated by the linear dependence of the reaction rate on the peroxide concentration up to at least 1 M H2O2. Steady-state conversion of a reducing substrate, guaiacol, is preceded by an activation phase, which is ascribed to the build-up of amino-acid radicals on the protein. The inactivation kinetics in the absence of reducing substrate are mono-exponential and shown to be concurrent with haem degradation up to 25 mM H2O2 (pH 8.0). At still higher peroxide concentrations, inactivation kinetics are biphasic, as a result of a remarkable protective effect of H2O2, involving the formation of superoxide and ferrocytochrome c-550.
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Affiliation(s)
- R E Diederix
- Gorlaeus Laboratories, Institute of Chemistry, Leiden University, the Netherlands
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34
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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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35
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Santus R, Patterson LK, Hug GL, Bazin M, Mazière JC, Morlière P. Interactions of superoxide anion with enzyme radicals: kinetics of reaction with lysozyme tryptophan radicals and corresponding effects on tyrosine electron transfer. Free Radic Res 2000; 33:383-91. [PMID: 11022847 DOI: 10.1080/10715760000300921] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The kinetics of O2*- reaction with semi-oxidized tryptophan radicals in lysozyme, Trp*(Lyz) have been investigated at various pHs and conformational states by pulse radiolysis. The Trp*(Lyz) radicals were formed by Br2*- oxidation of the 3-4 exposed Trp residues in the protein. At pH lower than 6.2, the apparent bimolecular rate is about 2 x 10(8) M(-1) s(-1); but drops to 8 x 10(7) M(-1) s(-1) or less above pH 6.3 and in CTAC micelles. Similarly, the apparent bimolecular rate constant for the intermolecular Trp*(Lyz) + Trp*(Lyz) recombination reaction is about (4-7 x 10(6) M(-1) s(-1)) at/or below pH 6.2 then drops to 1.3-1.6 x 10(6) M(-1) s(-1) at higher pH or in micelles. This behavior suggests important conformational and/or microenvironmental rearrangement with pH, leading to less accessible semi-oxidized Trp* residues upon Br2*- reaction. The kinetics of Trp*(Lyz) with ascorbate, a reducing species rather larger than O2*- have been measured for comparison. The well-established long range intramolecular electron transfer from Tyr residues to Trp radicals--leading to the repair of the semi-oxidized Trp*(Lyz) and formation of the tyrosyl phenoxyl radical is inhibited by the Trp*(Lyz) + O2*- reaction, as is most of the Trp*(Lyz) + Trp*(Lyz) reaction. However, the kinetic behavior of Trp*(Lyz) suggests that not all oxidized Trp residues are involved in the intermolecular recombination or reaction with O2*-. As the kinetics are found to be quite pH sensitive, this study demonstrates the effect of the protein conformation on O2*- reactivity. To our knowledge, this is the first report on the kinetics of a protein-O2*- reaction not involving the detection of change in the redox state of a prosthetic group to probe the reactivity of the superoxide anion.
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Affiliation(s)
- R Santus
- Laboratoire de Photobiologie, Muséum National d'Histoire Naturelle, Paris, France.
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36
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Audette M, Chen X, Houée-Levin C, Potier M, Le Maire M. Protein gamma-radiolysis in frozen solutions is a macromolecular surface phenomenon: fragmentation of lysozyme, citrate synthase and alpha-lactalbumin in native or denatured states. Int J Radiat Biol 2000; 76:673-81. [PMID: 10866290 DOI: 10.1080/095530000138349] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
PURPOSE To test whether radiolysis-induced fragmentation in frozen aqueous protein solution is dependent on solvent access to the surface of the protein or to the molecular mass of the polypeptide chain. MATERIALS AND METHODS 60Co gamma-irradiation of three proteins at -78 degrees C: lysozyme, citrate synthase and alpha-lactalbumin in their native state, with or without bound substrate, or denatured (random coil in urea/acid-denatured state). RESULTS By SDS-polyacrylamide gel electrophoresis/analysis of the protein-fragmentation process, it was found that for a given protein D37 values (dose to decrease the measured amount of protein, with an unaltered polypeptidic chain, to 37% of the initial amount) varied according to the state of the protein. D37 for denatured proteins was always much smaller than for native states, indicating a greater susceptibility to fragmentation. In urea, contrary to the native state, no well-defined fragments were observed. Radiolysis decay constants (K= 1/D37) increased with solvent-accessible surface area of these proteins estimated from their radii of gyration in the various states. This is shown also in previous data on native or SDS-denatured proteins. Denatured proteins which have a large surface area exposed to the solvent compared with native ones are more fragmented at equal doses. CONCLUSIONS It is concluded that D37 is directly related to the exposed surface area and not to the molecular mass of the polypeptide chain.
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Affiliation(s)
- M Audette
- LPCR, UMR 8610 CNRS-Université Paris-Sud, Orsay, France
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37
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Audette M, Blouquit Y, Houée-Levin C. Oxidative dimerization of proteins: role of tyrosine accessibility. Arch Biochem Biophys 2000; 376:217-20. [PMID: 10729208 DOI: 10.1006/abbi.2000.1709] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
PURPOSE To investigate the importance of two possible mechanisms of tyrosine oxidation on the yield of protein dimerization. The model chosen is hen and turkey egg-white lysozymes, which differ by seven amino acids, among which one tyrosine is in the 3 position. MATERIALS AND METHODS Aqueous solutions of proteins were oxidized by OH(*) or N(*)(3) free radicals produced by gamma or pulse irradiation in an atmosphere of N(2)O. Protein dimers were quantified by SDS-PAGE and reverse-phase HPLC. Dityrosines were identified by absorption and fluorescence. RESULTS Using N(*)(3) free radicals, the initial yields of dimerization are equal to (8.6 +/- 0.7) x 10(-9) mol J(-1) for both proteins. Using OH(*) free radicals, they become equal to (1.23 +/- 0.1) x 10(-8) and (4.42 +/- 0.1) x 10(-8) mol J(-1) for hen and turkey egg-white lysozymes, respectively (gamma radiolysis). DISCUSSION. N(*)(3) radicals react primarily with tryptophan residues only. Tyrosine gets oxidized by intramolecular long-range electron migration, whereas OH(*) may react directly with tyrosines. We propose a low participation of Tyr3 in turkey protein in the intramolecular process, because Tyr3 is far from all tryptophans. On the other hand, Tyr3 is very accessible to solvent and in a flexible area; thus collisions with OH(*) could easily be followed by intermolecular dimerization.
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Affiliation(s)
- M Audette
- LPCR, UMR 8610 CNRS-Université, Bât. 350, Centre Universitaire, Orsay Cedex, F-91405, France
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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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39
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Santus R, Patterson LK, Bazin M, Mazière JC, Morlière P. Intra and intermolecular charge effects on the reaction of the superoxide radical anion with semi-oxidized tryptophan in peptides and N-acetyl tryptophan. Free Radic Res 1998; 29:409-19. [PMID: 9925033 DOI: 10.1080/10715769800300451] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The reaction of the superoxide radical anion (O2-*), with the semi-oxidized tryptophan neutral radical (Trp*) generated from tryptophan (Trp) by pulse radiolysis has been observed in a variety of functionalized Trp derivatives including peptides. It is found that the reaction proceeds 4-5 times faster in positively charged peptides, such as Lys-Trp-Lys, Lys-Gly-Trp-Lys and Lys-Gly-Trp-Lys-O-tert-butyl, than in solutions of the negatively charged N-acetyl tryptophan (NAT). However, the reactivity of O2-* with the Trp* radical is totally inhibited upon binding of these peptides to micelles of negatively charged SDS and is reduced upon binding to native DNA. By contrast, no change in reactivity is observed in a medium containing CTAB, where the peptides cannot bind to the positively charged micelles. On the other hand, the reactivity of the Trp* radical formed from NAT with O2-* is reduced to half that of the free Trp* in buffer but is markedly increased in CTAB micelles. The models studied here incorporate elements of the complex environment in which Trp* and O2-* may be concomitantly formed in biological system and demonstrate the magnitude of the influence such elements may have on the kinetics of reactions involving these two species.
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Affiliation(s)
- R Santus
- Laboratoire de Photobiologie (INSERM U 312) Muséum National d'Histoire Naturelle, Paris, France.
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40
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Gunther MR, Tschirret-Guth RA, Witkowska HE, Fann YC, Barr DP, Ortiz De Montellano PR, Mason RP. Site-specific spin trapping of tyrosine radicals in the oxidation of metmyoglobin by hydrogen peroxide. Biochem J 1998; 330 ( Pt 3):1293-9. [PMID: 9494099 PMCID: PMC1219275 DOI: 10.1042/bj3301293] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The reaction between metmyoglobin and hydrogen peroxide produces both a ferryl-oxo heme and a globin-centred radical(s) from the two oxidizing equivalents of the hydrogen peroxide. Evidence has been presented for localization of the globin-centred radical on one tryptophan residue and tyrosines 103 and 151. When the spin-trapping agent 5,5-dimethyl-1-pyrroline N-oxide (DMPO) is included in the reaction mixture, a radical adduct has been detected, but the residue at which that adduct is formed has not been determined. Replacement of either tryptophans 7 and 14 or tyrosines 146 and 151 with phenylalanine has no effect on the formation of DMPO adduct in the reaction with hydrogen peroxide. When tyrosine 103 is replaced with phenylalanine, however, only DMPOX, a product of the oxidation of the spin-trap, is detected. Tyrosine-103 is, therefore, the site of radical adduct formation with DMPO. The spin trap 2-methyl-2-nitrosopropane (MNP), however, forms radical adducts with any recombinant sperm whale metmyoglobin that contains either tyrosine 103 or 151. Detailed spectral analysis of the DMPO and MNP radical adducts of isotopically substituted tyrosine radical yield complete structural determinations. The multiple sites of trapping support a model in which the unpaired electron density is spread over a number of residues in the population of metmyoglobin molecules, at least some of which are in equilibrium with each other.
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Affiliation(s)
- M R Gunther
- Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, National Institutes of Health, P.O. Box 12233 Research Triangle Park, NC 27709, USA
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Bergès J, Kassab E, Conte D, Adjadj E, Houée-Levin C. Ab-Initio Calculations on Arginine−Disulfide Complexes Modeling the One-Electron Reduction of Lysozyme. Comparison to an Experimental Reinvestigation. J Phys Chem A 1997. [DOI: 10.1021/jp963312q] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jacqueline Bergès
- Laboratoire de Chimie Théorique, Université P. et M. Curie, 4 place Jussieu, 75230 Paris, 05 France, and Institut Curie-Recherche, unite 350 INSERM, and L.P.C.R., Centre Universitaire, 91405 Orsay Cedex, France
| | - Emile Kassab
- Laboratoire de Chimie Théorique, Université P. et M. Curie, 4 place Jussieu, 75230 Paris, 05 France, and Institut Curie-Recherche, unite 350 INSERM, and L.P.C.R., Centre Universitaire, 91405 Orsay Cedex, France
| | - Daniel Conte
- Laboratoire de Chimie Théorique, Université P. et M. Curie, 4 place Jussieu, 75230 Paris, 05 France, and Institut Curie-Recherche, unite 350 INSERM, and L.P.C.R., Centre Universitaire, 91405 Orsay Cedex, France
| | - Elizabeth Adjadj
- Laboratoire de Chimie Théorique, Université P. et M. Curie, 4 place Jussieu, 75230 Paris, 05 France, and Institut Curie-Recherche, unite 350 INSERM, and L.P.C.R., Centre Universitaire, 91405 Orsay Cedex, France
| | - Chantal Houée-Levin
- Laboratoire de Chimie Théorique, Université P. et M. Curie, 4 place Jussieu, 75230 Paris, 05 France, and Institut Curie-Recherche, unite 350 INSERM, and L.P.C.R., Centre Universitaire, 91405 Orsay Cedex, France
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42
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Bobrowski K, Holcman J, Poznanski J, Wierzchowski KL. Pulse radiolysis studies of intramolecular electron transfer in model peptides and proteins. 7. Trp-->TyrO radical transformation in hen egg-white lysozyme. Effects of pH, temperature, Trp62 oxidation and inhibitor binding. Biophys Chem 1997; 63:153-66. [PMID: 9108690 DOI: 10.1016/s0301-4622(96)02226-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Intramolecular long-range electron transfer (LRET) in hen egg-white lysozyme (HEWL) accompanying Trp-->TyrO radical transformation was investigated in aqueous solution by pulse radiolysis as a function of pH (5.2-7.4) and temperature (283-328 K). The reaction was induced by highly selective oxidation of Trp with N3 radicals under low concentration of the reactants but at a high HEWL/N3 molar ratio, so that more than 99% of the oxidized protein molecules contained only a single tryptophyl radical. Synchronous decay of Trp and build-up of TyrO conformed satisfactorily to first-order kinetics, indicating that LRET involved either one or more Trp./Tyr redox pairs characterized by similar rate constants. The rate constant of LRET, k5, increased monotonously with decreasing pH showing the following characteristics: (i) in the pH range 7.4-5.2 the plot of k5 against pH was sigmoidal in shape, reflecting protonation of Glu35 (pKa approximately 6) and pointing to involvement of conformational control of the kinetics of LRET, (ii) below pH 5.2 a sharp increase in k5 was observed due to the protonation of Trp to form TrpH.+, which is known to oxidize tyrosine faster than does Trp.. Arrhenius plots of the temperature-dependence of k5 showed that the activation energy of LRET varies both with temperature and the protonation state of the enzyme. The activation energies are in the range 7.6-56.0 kJ mol-1, and are similar to those for activation of amide hydrogen exchange in native HEWL below its denaturation temperature. Selective oxidation by ozone of the Trp62 indole side-chain in HEWL to N'-formylkynurenine (NFKyn62-HEWL) caused a large drop in the initial yield of Trp. radicals, G(Trp.)i. This was accompanied by a relatively small decrease in k5 but selective oxidation by ozone had a pronounced effect on its temperature-dependence. Taken together these observations indicate that of the six tryptophans present in HEWL Trp62 contributes about 50% to the yield of the observed LRET. In the enzyme-inhibitor complex, HEWL(GlcNAc)3, where Trp62 and Trp63 are completely shielded from the solvent by the bound triacetylchitotriose, G(Trp.)i was lower than in NFKyn62-HEWL, and both the kinetic and energetic characteristics of LRET, observed at pH 5.2, were again somewhat different than in HEWL alone. Considering known solvent accessibilities of tryptophans in the complex, the observed LRET process in HEWL(GlcNAc)3 was assigned to Trp123. Theoretical evaluation of the electronic coupling for the dominant LRET pathways between all the potential Trp/Tyr redox couples in HEWL, with help of the PATHWAYS model, enabled Trp623/Tyr53, Trp63/Tyr53 and Trp123/Tyr23 to be identified as the pairs involved in the experimentally observed electron transfer.
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Affiliation(s)
- K Bobrowski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warszawa, Poland
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43
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Weinkauf R, Schanen P, Metsala A, Schlag EW, Bürgle M, Kessler H. Highly Efficient Charge Transfer in Peptide Cations in the Gas Phase: Threshold Effects and Mechanism. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp960926m] [Citation(s) in RCA: 169] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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44
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Saha A, Mandal P, Bhattacharyya S. Radiation-induced inactivation of enzymes—A review. Radiat Phys Chem Oxf Engl 1993 1995. [DOI: 10.1016/0969-806x(94)00130-c] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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45
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Smith GJ. New trends in photobiology (invited review) photodegradation of keratin and other structural proteins. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 1995. [DOI: 10.1016/1011-1344(94)07104-v] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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46
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Smith GJ. Photoinduced electron transfer and free radical formation in dry keratin protein. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 1994. [DOI: 10.1016/1011-1344(93)06961-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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47
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Saha A, Mandal PC, Bhattacharyya SN. Tyrosine residues in unirradiated and gamma-irradiated dihydroorotate dehydrogenase: fluorimetric and second-derivative absorption spectrophotometric studies. Int J Radiat Biol 1993; 63:557-64. [PMID: 8099102 DOI: 10.1080/09553009314450731] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effect of gamma-radiation on tyrosine residues of dihydroorotate dehydrogenase under different conditions was investigated by means of fluorescence spectroscopy and second-derivative spectrophotometry. No change in the fluorescence spectral distribution was observed when unirradiated and irradiated enzyme were denatured in guanidine hydrochloride. However, decreases in fluorescence intensity in irradiated samples indicates a radiation-induced modification of tyrosine residues. The fluorescence intensity at 340 nm decreased exponentially with radiation dose in aerated medium but non-exponentially under argon and nitrous oxide-saturated conditions. The percentage loss of tyrosine fluorescence under different conditions was determined. The number of tyrosine residues left intact following irradiation at a dose for 50% inactivation under different conditions was measured by second-derivative absorption spectrophotometry. The results obtained from both these methods show that the hydroxyl radical is less efficient in inducing radiation damage of tyrosine in aerated conditions compared with that under deoxygenated conditions. This lower efficiency of the hydroxyl radical in aerated medium has been attributed to the protective effect of oxygen and/or the superoxide radical anion.
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Affiliation(s)
- A Saha
- Nuclear Chemistry Division, Saha Institute of Nuclear Physics, Calcutta, India
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48
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Lee H, Faraggi M, Klapper MH. Long range electron transfer along an alpha-helix. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1159:286-94. [PMID: 1390934 DOI: 10.1016/0167-4838(92)90058-l] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The many observations of long range electron transfer in proteins raises the question of whether a protein's structure can influence the rate or path of such transfers, and if so, then how. To answer these questions requires information on which of the various structural elements composing proteins support long range electron transfer. In this report, we present evidence for long range electron transfer along the alpha-helix of a synthetic leucine zipper dimer. We also present electron transfer rate data obtained with other helical peptides.
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Affiliation(s)
- H Lee
- Department of Chemistry, Ohio State University, Columbus 43210
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