1
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Radomska K, Lebelt L, Wolszczak M. Aggregation of Albumins under Reductive Radical Stress. Int J Mol Sci 2024; 25:9009. [PMID: 39201695 PMCID: PMC11354859 DOI: 10.3390/ijms25169009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2024] [Revised: 08/08/2024] [Accepted: 08/15/2024] [Indexed: 09/03/2024] Open
Abstract
The reactions of radicals with human serum albumin (HSA) under reductive stress conditions were studied using pulse radiolysis and photochemical methods. It was proved that irradiation of HSA solutions under reductive stress conditions results in the formation of stable protein aggregates. HSA aggregates induced by ionizing radiation are characterized by unique emission, different from the UV emission of non-irradiated solutions. The comparison of transient absorption spectra and the reactivity of hydrated electrons (eaq-) with amino acids or HSA suggests that electron attachment to disulfide bonds is responsible for the transient spectrum recorded in the case of albumin solutions. The reactions of eaq- and CO2•- with HSA lead to the formation of the same products. Recombination of sulfur-centered radicals plays a crucial role in the generation of HSA nanoparticles, which are stabilized by intermolecular disulfide bonds. The process of creating disulfide bridges under the influence of ionizing radiation is a promising method for the synthesis of biocompatible protein nanostructures for medical applications. Our Raman spectroscopy studies indicate strong modification of disulfide bonds and confirm the aggregation of albumins as well. Low-temperature measurements indicate the possibility of electron tunneling through the HSA protein structure to specific CyS-SCy bridges. The current study showed that the efficiency of HSA aggregation depends on two main factors: dose rate (number of pulses per unit time in the case of pulse radiolysis) and the temperature of the irradiated solution.
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Affiliation(s)
- Karolina Radomska
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, 93-590 Lodz, Poland;
- Centre of Papermaking and Printing, Lodz University of Technology, Wolczanska 221, 93-005 Lodz, Poland
| | - Liwia Lebelt
- Bioorganic Chemistry Laboratory, Faculty of Pharmacy, Medical University of Lodz, Muszynskiego 1, 90-151 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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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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3
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Radomska K, Wolszczak M. Spontaneous and Ionizing Radiation-Induced Aggregation of Human Serum Albumin: Dityrosine as a Fluorescent Probe. Int J Mol Sci 2022; 23:ijms23158090. [PMID: 35897662 PMCID: PMC9331647 DOI: 10.3390/ijms23158090] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 07/19/2022] [Accepted: 07/20/2022] [Indexed: 02/04/2023] Open
Abstract
The use of spectroscopic techniques has shown that human serum albumin (HSA) undergoes reversible self-aggregation through protein−protein interactions. It ensures the subsequent overlapping of electron clouds along with the stiffening of the conformation of the interpenetrating network of amino acids of adjacent HSA molecules. The HSA oxidation process related to the transfer of one electron was investigated by pulse radiolysis and photochemical methods. It has been shown that the irradiation of HSA solutions under oxidative stress conditions results in the formation of stable protein aggregates. The HSA aggregates induced by ionizing radiation are characterized by specific fluorescence compared to the emission of non-irradiated solutions. We assume that HSA dimers are mainly responsible for the new emission. Dityrosine produced by the intermolecular recombination of protein tyrosine radicals as a result of radiolysis of an aqueous solution of the protein is the main cause of HSA aggregation by cross-linking. Analysis of the oxidation process of HSA confirmed that the reaction of mild oxidants (Br2•−, N3•, SO4•−) with albumin leads to the formation of covalent bonds between tyrosine residues. In the case of •OH radicals and partly, Cl2•−, species other than DT are formed. The light emission of this species is similar to the emission of self-associated HSA.
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4
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Liang SP, Masquelier E, Morse DE, Gordon MJ, Sepunaru L. Low Voltage Voltammetry Probes Proton Dissociation Equilibria of Amino Acids and Peptides. Anal Chem 2022; 94:4948-4953. [PMID: 35290024 DOI: 10.1021/acs.analchem.1c03371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Platinum-catalyzed electrochemical reduction of dissociable protons at low potentials was used to investigate proton dissociation equilibria of freely diffusing and peptide-incorporated charged amino acids. We first demonstrate with five charged essential amino acids and their analogs that the electrochemically induced deprotonation of each amino acid occurs at distinct formal reduction potential. Moreover, the observed direct reduction for all the charged species, excluding arginine, occurs at low potentials suitable for investigation under aqueous conditions (-0.4 to -0.9 V vs Ag/AgCl). The direct proton reduction was resolved via deconvolution of the observed differential pulse voltammogram (DPV) from background hydronium reduction and water electrolysis. A linear correlation was found between the formal reduction potentials and the pKa values of the dissociable protons hosted by various molecular moieties in the amino acids and their analogs and further verified with tripeptides. DPV of poly(l-lysine) decamer (Lys10) distinctively resolved the pKa values of the amino groups in the side chains and N-terminus, at a resolution not possible by conventional acid-base titration. This work demonstrates selective electrochemical titration of dissociable protons in charged amino acids in the free state and as residues in biomolecules, as well as the utility of DPV to indirectly interrogate local electrostatic environments that are essential to the stability and function of biomolecules.
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Affiliation(s)
- Sheng-Ping Liang
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Eloise Masquelier
- Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Daniel E Morse
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106, United States.,Institute of Collaborative Biotechnologies, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Michael J Gordon
- Institute of Collaborative Biotechnologies, University of California, Santa Barbara, Santa Barbara, California 93106, United States.,Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Lior Sepunaru
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
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5
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Marciniak B, Bobrowski K. Photo- and Radiation-Induced One-Electron Oxidation of Methionine in Various Structural Environments Studied by Time-Resolved Techniques. Molecules 2022; 27:1028. [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] [MESH Headings] [Grants] [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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Affiliation(s)
- Bronislaw Marciniak
- Center for Advanced Technology, and Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznanskiego 10, 61-712 Poznan, Poland
| | - Krzysztof Bobrowski
- Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw, Poland
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Gebicki JM, Nauser T. Initiation and Prevention of Biological Damage by Radiation-Generated Protein Radicals. Int J Mol Sci 2021; 23:ijms23010396. [PMID: 35008823 PMCID: PMC8745036 DOI: 10.3390/ijms23010396] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 12/27/2021] [Accepted: 12/27/2021] [Indexed: 12/23/2022] Open
Abstract
Ionizing radiations cause chemical damage to proteins. In aerobic aqueous solutions, the damage is commonly mediated by the hydroxyl free radicals generated from water, resulting in formation of protein radicals. Protein damage is especially significant in biological systems, because proteins are the most abundant targets of the radiation-generated radicals, the hydroxyl radical-protein reaction is fast, and the damage usually results in loss of their biological function. Under physiological conditions, proteins are initially oxidized to carbon-centered radicals, which can propagate the damage to other molecules. The most effective endogenous antioxidants, ascorbate, GSH, and urate, are unable to prevent all of the damage under the common condition of oxidative stress. In a promising development, recent work demonstrates the potential of polyphenols, their metabolites, and other aromatic compounds to repair protein radicals by the fast formation of less damaging radical adducts, thus potentially preventing the formation of a cascade of new reactive species.
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Affiliation(s)
- Janusz M. Gebicki
- Department of Biological Sciences, Macquarie University, Sydney 2109, Australia
- Correspondence:
| | - Thomas Nauser
- Departement für Chemie und Angewandte Biowissenschaften, Eidgenössische Technische Hochschule, 8093 Zurich, Switzerland;
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7
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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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8
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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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9
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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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10
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Spectral Probe for Electron Transfer and Addition Reactions of Azide Radicals with Substituted Quinoxalin-2-Ones in Aqueous Solutions. Int J Mol Sci 2021; 22:ijms22020633. [PMID: 33435233 PMCID: PMC7828026 DOI: 10.3390/ijms22020633] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 01/03/2021] [Accepted: 01/07/2021] [Indexed: 12/30/2022] Open
Abstract
The azide radical (N3●) is one of the most important one-electron oxidants used extensively in radiation chemistry studies involving molecules of biological significance. Generally, it was assumed that N3● reacts in aqueous solutions only by electron transfer. However, there were several reports indicating the possibility of N3● addition in aqueous solutions to organic compounds containing double bonds. The main purpose of this study was to find an experimental approach that allows a clear assignment of the nature of obtained products either to its one-electron oxidation or its addition products. Radiolysis of water provides a convenient source of one-electron oxidizing radicals characterized by a very broad range of reduction potentials. Two inorganic radicals (SO4●-, CO3●-) and Tl2+ ions with the reduction potentials higher, and one radical (SCN)2●- with the reduction potential slightly lower than the reduction potential of N3● were selected as dominant electron-acceptors. Transient absorption spectra formed in their reactions with a series of quinoxalin-2-one derivatives were confronted with absorption spectra formed from reactions of N3● with the same series of compounds. Cases, in which the absorption spectra formed in reactions involving N3● differ from the absorption spectra formed in the reactions involving other one-electron oxidants, strongly indicate that N3● is involved in the other reaction channel such as addition to double bonds. Moreover, it was shown that high-rate constants of reactions of N3● with quinoxalin-2-ones do not ultimately prove that they are electron transfer reactions. The optimized structures of the radical cations (7-R-3-MeQ)●+, radicals (7-R-3-MeQ)● and N3● adducts at the C2 carbon atom in pyrazine moiety and their absorption spectra are reasonably well reproduced by density functional theory quantum mechanics calculations employing the ωB97XD functional combined with the Dunning's aug-cc-pVTZ correlation-consistent polarized basis sets augmented with diffuse functions.
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11
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Hellwig M. Analysis of Protein Oxidation in Food and Feed Products. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:12870-12885. [PMID: 32237708 DOI: 10.1021/acs.jafc.0c00711] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Food and feed proteins are subject to oxidation reactions during production, processing, and storage. Several individual oxidized amino acids have been described in model systems and food; however, protein oxidation in food is still mostly assessed by the analysis of protein carbonylation. In the present review, the chemistry of protein oxidation and its implications for protein functionality, food flavor, and nutritional physiology are briefly summarized. Limitations of generic methods targeting redox-relevant functional groups and properties of typical reaction products, such as the determination of protein carbonyls and fluorescence spectroscopy, are presented. Methods for the quantitation of individual oxidation products of susceptible amino acids, such as cysteine, methionine, phenylalanine, tyrosine, and tryptophan, are reported. Special regard is paid to limitations resulting from the required hydrolysis procedures and unintended formation of the analytes during sample pretreatment. If available, results from food analysis obtained by different methods are compared. Suggestions and requirements for future works on protein oxidation in food and nutrition are given.
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Affiliation(s)
- Michael Hellwig
- Chair of Food Chemistry, Technische Universität Dresden, D-01062 Dresden, Germany
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12
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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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13
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Affiliation(s)
- Michael Hellwig
- Professur für LebensmittechemieTechnische Universität Dresden D-01062 Dresden Deutschland
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14
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Abstract
Oxidation is one of the deterioration reactions of proteins in food, the importance of which is comparable to others such as Maillard, lipation, or protein-phenol reactions. While research on protein oxidation has led to a precise understanding of the processes and consequences in physiological systems, knowledge about the specific effects of protein oxidation in food or the role of "oxidized" dietary protein for the human body is comparatively scarce. Food protein oxidation can occur during the whole processing axis, from primary production to intestinal digestion. The present review summarizes the current knowledge and mechanisms of food protein oxidation from a chemical, technological, and nutritional-physiological viewpoint and gives a comprehensive classification of the individual reactions. Different analytical approaches are compared, and the relationship between oxidation of food proteins and oxidative stress in vivo is critically evaluated.
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Affiliation(s)
- Michael Hellwig
- Chair of Food Chemistry, Technische Universität Dresden, D-01062, Dresden, Germany
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15
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Adhikari S, Mukherjee T. Kinetics of Free Radical Reactions of Some Biologically Important Compounds as Studied by Pulse Radiolysis. PROGRESS IN REACTION KINETICS AND MECHANISM 2019. [DOI: 10.3184/007967401103165307] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Soumyakanti Adhikari
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Tulsi Mukherjee
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
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Nauser T, Gebicki JM. Physiological Concentrations of Ascorbate Cannot Prevent the Potentially Damaging Reactions of Protein Radicals in Humans. Chem Res Toxicol 2017; 30:1702-1710. [PMID: 28745873 DOI: 10.1021/acs.chemrestox.7b00160] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The principal initial biological targets of free radicals formed under conditions of oxidative stress are the proteins. The most common products of the interaction are carbon-centered alkyl radicals which react rapidly with oxygen to form peroxyl radicals and hydroperoxides. All these species are reactive, capable of propagating the free radical damage to enzymes, nucleic acids, lipids, and endogenous antioxidants, leading finally to the pathologies associated with oxidative stress. The best chance of preventing this chain of damage is in early repair of the protein radicals by antioxidants. Estimate of the effectiveness of the physiologically significant antioxidants requires knowledge of the antioxidant tissue concentrations and rate constants of their reaction with protein radicals. Previous studies by pulse radiolysis have shown that only ascorbate can repair the Trp and Tyr protein radicals before they form peroxyl radicals under physiological concentrations of oxygen. We have now extended this work to other protein C-centered radicals generated by hydroxyl radicals because these and many other free radicals formed under oxidative stress can produce secondary radicals on virtually any amino acid residue. Pulse radiolysis identified two classes of rate constants for reactions of protein radicals with ascorbate, a faster one in the range (9-60) × 107 M-1 s-1 and a slow one with a range of (0.5-2) × 107 M-1 s-1. These results show that ascorbate can prevent further reactions of protein radicals only in the few human tissues where its concentration exceeds about 2.5 mM.
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Affiliation(s)
- Thomas Nauser
- Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology , Zurich CH8093, Switzerland
| | - Janusz M Gebicki
- Department of Biological Sciences, Macquarie University , Sydney, New South Wales 2109, Australia
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18
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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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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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Domazou AS, Zhu H, Koppenol WH. Fast repair of protein radicals by urate. Free Radic Biol Med 2012; 52:1929-36. [PMID: 22406318 DOI: 10.1016/j.freeradbiomed.2012.02.045] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 02/17/2012] [Accepted: 02/28/2012] [Indexed: 01/23/2023]
Abstract
The repair of tryptophan and tyrosine radicals in proteins by urate was studied by pulse radiolysis. In chymotrypsin, urate repairs tryptophan radicals efficiently with a rate constant of 2.7 × 10(8)M(-1)s(-1), ca. 14 times higher than the rate constant derived for N-acetyltryptophan amide, 1.9 × 10(7)M(-1)s(-1). In contrast, no repair of tryptophan radicals was observed in pepsin, which indicates a rate constant smaller than 6 × 10(7)M(-1)s(-1). Urate repairs tyrosine radicals in pepsin with a rate constant of 3 × 10(8)M(-1)s(-1)-ca. 12 times smaller than the rate constant reported for free tyrosine-but not in chymotrypsin, which implies an upper limit of 1 × 10(6)M(-1)s(-1) for the corresponding rate constant. Intra- and intermolecular electron transfer from tyrosine residues to tryptophan radicals is observed in both proteins, however, to different extents and with different rate constants. Urate inhibits electron transfer in chymotrypsin but not in pepsin. Our results suggest that urate repairs the first step on the long path to protein modification and prevents damage in vivo. It may prove to be a very important repair agent in tissue compartments where its concentration is higher than that of ascorbate. The product of such repair, the urate radical, can be reduced by ascorbate. Loss of ascorbate is then expected to be the net result, whereas urate is conserved.
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Affiliation(s)
- Anastasia S Domazou
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich CH-8093, Switzerland.
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21
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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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22
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Arenas A, Vasquez R, López-Alarcón C, Lissi E, Silva E. Oxidative Damage of Lysozyme and Human Serum Albumin and Their Mixtures. A Comparison of Photosensitized and Peroxyl Radical Promoted Processes. Protein J 2011; 30:359-65. [DOI: 10.1007/s10930-011-9341-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Costanzo F, Sulpizi M, Valle RGD, Sprik M. The oxidation of tyrosine and tryptophan studied by a molecular dynamics normal hydrogen electrode. J Chem Phys 2011; 134:244508. [DOI: 10.1063/1.3597603] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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24
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Brun E, Blouquit Y, Duchambon P, Malosse C, Chamot-Rooke J, Sicard-Roselli C. Oxidative stress induces mainly human centrin 2 polymerisation. Int J Radiat Biol 2010; 86:657-68. [PMID: 20586543 DOI: 10.3109/09553001003734584] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
PURPOSE To determine the human centrin 2 (Hscen 2) protein response to oxidising radicals in vitro and to evaluate the consequences on its biological functions. MATERIALS AND METHODS Hscen 2 was submitted to hydroxyl and azide radicals produced by radiolysis in the absence of oxygen. The resulting products were characterised by biochemical, spectroscopic and mass spectrometry techniques. Their thermodynamics parameters of complexation with C-terminal fragment of Xeroderma pigmentosum C protein (C-XPC), one of the Hscen 2 cellular partners, were quantified by isothermal titration calorimetry (ITC). RESULTS Both hydroxyl and azide radicals induce centrin 2 polymerisation as we characterised several intermolecular cross-links generating dimers, trimers, tetramers and higher molecular mass species. These cross-links result from the formation of a covalent bond between the only tyrosine residue (Tyr 172) located in the C-terminal region of each monomer. Remarkably, dimerisation occurs for doses as low as a few grays. Moreover, this Hscen2 dimer has a lower affinity and stoechiometry binding to C-XPC. CONCLUSIONS These results show that as oxidative radicals induce high proportions of irreversible damages (polymerisation) centrin 2 is highly sensitive to ionising radiation. This could have important consequences on its biological functions.
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Affiliation(s)
- Emilie Brun
- Laboratoire de Chimie Physique, CNRS UMR 8000, Université Paris-Sud 11, Bât. 350, Orsay Cedex, France
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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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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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Page MA, Shisler JL, Mariñas BJ. Kinetics of adenovirus type 2 inactivation with free chlorine. WATER RESEARCH 2009; 43:2916-2926. [PMID: 19439336 DOI: 10.1016/j.watres.2009.03.047] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2009] [Revised: 03/28/2009] [Accepted: 03/31/2009] [Indexed: 05/27/2023]
Abstract
The objective of this study was to elucidate the effects of pH, temperature, and other relevant water quality parameters on the kinetics of adenovirus serotype 2 inactivation with free chlorine. Over a pH range of 6.5-10, a temperature range of 1-30 degrees C, and in a variety of water types, free chlorine was highly effective against adenovirus type 2. Its disinfection efficacy decreased with increasing pH and decreasing temperature, yet was unaffected by hardness and buffering species. Under the most challenging conditions investigated in this study (pH 10, 1 degrees C), a four-log reduction of adenovirus viability would be achieved at a CT value of 2.6mgCl(2)min/L. The inactivation kinetics was characterized by three phases of inactivation under most conditions. The first phase resulted from a reaction involving primarily the hypochlorous acid species and was characterized by rapid inactivation of viruses to a limit that increased with decreasing pH and increasing temperature. After reaching this limit, adenovirus exhibited two subsequent phases of inactivation at lesser rates that were not affected by temperature or pH. As with the first phase of kinetics, a limit of inactivation was approached in the second phase that decreased with increasing pH, and after which the kinetics was characterized by a third and final phase. An inactivation model consistent with these observations was found to provide adequate representation for the free chlorine inactivation of adenovirus serotype 2 as well as that reported in the literature for other adenovirus serotypes.
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Affiliation(s)
- Martin A Page
- Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 205 N. Mathews Ave., Urbana, IL 61801, USA; Ctr. of Advanced Materials for the Purification of Water with Systems (WaterCAMPWS), 1206 W. Green St., Urbana, IL 61801, USA
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28
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Domazou AS, Koppenol WH, Gebicki JM. Efficient repair of protein radicals by ascorbate. Free Radic Biol Med 2009; 46:1049-57. [PMID: 19185609 DOI: 10.1016/j.freeradbiomed.2009.01.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Revised: 12/22/2008] [Accepted: 01/06/2009] [Indexed: 11/15/2022]
Abstract
Protein radicals were selectively generated by reaction with azide radicals on Trp and Tyr residues in insulin, beta-lactoglobulin, pepsin, chymotrypsin, and bovine serum albumin at rate constants in the range (2.9-19)x10(8) M(-1) s(-1). Monohydrogen ascorbate reduced tryptophanyl radicals in chymotrypsin and pepsin with rate constants in the narrow range of (1.6-1.8)x10(8) M(-1) s(-1), whereas beta-lactoglobulin tryptophanyl radicals reacted almost 10 times slower. The corresponding values for the protein tyrosyl radicals were about an order of magnitude smaller. Comparison of the rate constants of reactions of free and protein-bound tryptophanyl and tyrosyl radicals showed that, in most cases, the location of the radicals in the protein chain did not constitute a major barrier to the reaction with monohydrogen ascorbate. The results suggest that, under physiological concentrations of dioxygen, monohydrogen ascorbate is likely to be a significant target of protein radicals. It seems likely, therefore, that reaction with protein radicals may be responsible for much of the well-documented loss of ascorbate in living organisms subjected to oxidative stress.
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Affiliation(s)
- Anastasia S Domazou
- Department of Chemistry and Applied Biosciences, Institute of Inorganic Chemistry, Swiss Federal Institute of Technology, Zurich, Switzerland
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Kowalczyk A, Serafin E, Puchała M. Inactivation of chosen dehydrogenases by the products of water radiolysis and secondary albumin and haemoglobin radicals. Int J Radiat Biol 2008; 84:15-22. [PMID: 17852555 DOI: 10.1080/09553000701616056] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
PURPOSE Inactivation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), alcohol dehydrogenase (ADH) and lactate dehydrogenase (LDH) by products of water radiolysis and by secondary radicals localized on haemoglobin (Hb) and human albumin (HSA) was studied. MATERIALS AND METHODS Aqueous solutions of ADH, GAPDH and LDH were irradiated under air and under nitrous oxide (N2O) in the absence and in the presence of Hb or HSA. In order to determine the effectiveness of inactivation of the enzymes by radicals localized on Hb and HSA, the inactivation efficiency determined experimentally was compared with that calculated under assumption that only hydroxyl radicals are responsible for the enzyme inactivation. RESULTS In the absence of other proteins, under air, GAPDH showed the highest radiation sensitivity, followed by ADH and LDH. The sequence was reverse under anaerobic atmosphere. Oxygen increased considerably the inactivation of GAPDH and ADH. Secondary albumin and haemoglobin radicals brought about considerable inactivation of GAPGH and ADH. Albumin radicals (HSA) generated under N2O inactivated GAPDH and ADH more effectively than haemoglobin radicals (Hb). Under air, however, inactivation of GAPDH and ADH by haemoglobin peroxyl radicals was higher than by albumin peroxyl radicals. LDH was resistant to inactivation by haemoglobin and albumin radicals, and peroxides of these proteins. CONCLUSIONS In the light of these results and literature data, the observed differences in the effectiveness of inactivation of the dehydrogenases studied by secondary protein radicals depend on the amino acid residues present at the active site and in its close neighborhood and on the number of amino acid residues available on the protein surface.
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Viteri G, Edwards AM, De la Fuente J, Silva E. Study of the Interaction Between Triplet Riboflavin and the α-, βH- and βL-Crystallins of the Eye Lens ¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2003)0770535sotibt2.0.co2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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31
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Zhu H, Chen S, Hao S, Zhang Z, Wang W, Yao S. Double roles of hydroxycinnamic acid derivatives in protection against lysozyme oxidation. Biochim Biophys Acta Gen Subj 2006; 1760:1810-8. [PMID: 17010522 DOI: 10.1016/j.bbagen.2006.08.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Revised: 08/11/2006] [Accepted: 08/11/2006] [Indexed: 10/24/2022]
Abstract
Oxidative damage to protein has been implicated in a number of diseases. Much interest has been focused on preventing oxidative damage to protein. Here we showed that hydroxycinnamic acid derivatives (HCA) were able to inhibit the cross-linking of protein induced by riboflavin-mediated photooxidation. HCA were also found to strongly protect lysozyme from gamma rays irradiation. The antioxidative properties of HCA were further studied by laser flash photolysis. Mechanism of antioxidant activities of HCA on lysozyme oxidation was discussed. HCA were found to protect protein against oxidation by scavenging oxidizing species and repairing the damaged protein.
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Affiliation(s)
- Hongping Zhu
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China
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Barone V, Newton MD, Improta R. Dissociative Electron Transfer in Donor−Peptide−Acceptor Systems: Results for Kinetic Parameters from a Density Functional/Polarizable Continuum Model. J Phys Chem B 2006; 110:12632-9. [PMID: 16800595 DOI: 10.1021/jp0557969] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The main structural and electronic factors playing a role in intramolecular dissociative electron transfer of a simple donor-peptide-acceptor (D-peptide-A) model have been investigated by an integrated computational protocol based on the density functional theory, its time-dependent extension, and the polarizable continuum model. Our results allow us to elucidate the electronic states involved in the process and how they are perturbed by the orientation of the donor and the acceptor with respect to the peptide chain and by the presence of the solvent. We also report a semiquantitative estimation of the rate constant governing electron transfer obtained by a direct quantum mechanical evaluation of all the terms entering the kinetic expressions based on the Marcus theory and its extensions.
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Affiliation(s)
- Vincenzo Barone
- Dipartimento di Chimica, Università Federico II, Complesso Monte S. Angelo, via Cintia, I-80126 Napoli, Italy
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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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Morozova OB, Hore PJ, Sagdeev RZ, Yurkovskaya AV. Intramolecular Electron Transfer in Lysozyme Studied by Time-Resolved Chemically Induced Dynamic Nuclear Polarization. J Phys Chem B 2005; 109:21971-8. [PMID: 16853855 DOI: 10.1021/jp053394v] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The kinetics of the chemically induced dynamic nuclear polarization (CIDNP) produced in reactions of hen lysozyme with photosensitizers have been studied for the native state of the protein at pH 3.8 and for two denatured states. The latter were generated by raising the temperature to 80 degrees C or by combining a temperature rise (to 50 degrees C) with the addition of chemical denaturant (10 M urea). Detailed analysis of the CIDNP time dependence on a microsecond time scale revealed that, in both denatured states, intramolecular electron transfer (IET) from a tyrosine residue to the cation radical of a tryptophan residue (rate constant k(f)) is highly efficient and plays a decisive role in the evolution of the nuclear polarization. To describe the observed CIDNP kinetics with a self-consistent set of parameters, IET in the reverse direction, from a tryptophan residue to a tyrosine residue radical (rate constant k(r)), has also to be taken into account. The IET rate constants determined by analysis of the CIDNP kinetics are, at 80 degrees C: k(f) = 1 x 10(5) s(-1) and k(r) = 1 x 10(4) s(-1); at 50 degrees C in the presence of 10 M urea: k(f) = 7 x 10(4) s(-1), k(r) = 1 x 10(4) s(-1). IET does not appear to influence the CIDNP kinetics of the native state.
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Affiliation(s)
- Olga B Morozova
- International Tomography Center of SB RAS, 630090, Institutskaya 3a, Novosibirsk, Russia
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35
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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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Morozova OB, Yurkovskaya AV, Sagdeev RZ. Reversibility of Electron Transfer in Tryptophan−Tyrosine Peptide in Acidic Aqueous Solution Studied by Time-Resolved CIDNP. J Phys Chem B 2005; 109:3668-75. [PMID: 16851405 DOI: 10.1021/jp047151z] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Time-resolved chemically induced dynamic nuclear polarization (CIDNP) has been used to study electron transfer reactions in tryptophan-tyrosine peptide under strongly acidic conditions. It is demonstrated that a decrease in pH from 2.4 to 1.6 reduces the overall efficiency of intramolecular electron transfer from the tyrosine residue to the oxidized tryptophan residue. A detailed analysis of the CIDNP kinetics revealed that the rate constant of this reaction k(f) stays unchanged upon pH variation, whereas the rate constant of electron transfer in the opposite direction k(r) increases with decreasing pH. The values of the rate constants extracted from model simulations are as follows: k(f) = (5.5 +/- 0.5) x 10(5) s(-1); k(r) = (5.5 +/- 1.0) x 10(4) s(-1) at pH 2.4, (1.2 +/- 0.2) x 10(5) s(-1) at pH 2.0, and (3.2 +/- 0.4) x 10(5) s(-1) at pH 1.6. The pH dependence of log K = log(k(f)/k(r)) is linear and allows for the determination of the difference between the one-electron reduction potentials of the tryptophanyl and tyrosyl radicals in the peptide. The efficiency of IET in acidic aqueous solution containing 10 M urea-d(4) was estimated.
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Affiliation(s)
- Olga B Morozova
- International Tomography Center of SB RAS, Institutskaya 3a, 630090 Novosibirsk, Russia
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Improta R, Antonello S, Formaggio F, Maran F, Rega N, Barone V. Understanding Electron Transfer across Negatively-Charged Aib Oligopeptides. J Phys Chem B 2004; 109:1023-33. [PMID: 16866475 DOI: 10.1021/jp045797l] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The physicochemical effects modulating the conformational behavior and the rate of intramolecular dissociative electron transfer in phthalimide-Aibn-peroxide peptides (n = 0-3) have been studied by an integrated density functional/continuum solvent model. We found that three different orientations of the phthalimide ring are possible, labeled Phihel, PhiC7, and PhipII. In the condensed phase, they are very close in energy when the system is neutral and short. When the peptide chain length increases and the system is negatively charged, Phihel becomes instead the most stable conformer. Our calculations confirm that the 3(10)-helix is the most stable secondary structure for the peptide bridge. However, upon charge injection in the phthalimide end of the phthalimide-Aib3-peroxide, the peptide bridge can adopt an alpha-helix conformation as well. The study of the dependence of the frontier orbitals on the length and on the conformation of the peptide bridge (in agreement with experimental indications) suggests that for n = 3 the process could be influenced by a 3(10) --> alpha-helix conformational transition of the peptide chain.
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Affiliation(s)
- Roberto Improta
- Dipartimento di Chimica, Università di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia, 80126 Napoli, Italy
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Bediako-Amoa I, Sutherland TC, Li CZ, Silerova R, Kraatz HB. Electrochemical and Surface Study of Ferrocenoyl Oligopeptides. J Phys Chem B 2003. [DOI: 10.1021/jp0368785] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Irene Bediako-Amoa
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
| | - Todd C. Sutherland
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
| | - Chen-Zhong Li
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
| | - Roberta Silerova
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
| | - Heinz-Bernhard Kraatz
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
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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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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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41
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Viteri G, Edwards AM, De la Fuente J, Silva E. Study of the interaction between triplet riboflavin and the alpha-, betaH- and betaL-crystallins of the eye lens. Photochem Photobiol 2003; 77:535-40. [PMID: 12812297 DOI: 10.1562/0031-8655(2003)077<0535:sotibt>2.0.co;2] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Time-resolved photolysis studies of riboflavin (RF) were carried out in the presence and absence of alpha-, betaH- and betaL-crystallins of bovine eye lens. The transient absorption spectra, recorded 5 micros after the laser pulse, reveal the presence of the absorption band (625-675 nm) of the RF neutral triplet state (tau = 42 micros) accompanied by the appearance of a long-lived absorption (tau = 320 micros) in the 500-600 nm region due to the formation of the semireduced RF radical. The RF excited state is quenched by the crystallin proteins through a mechanism that involves electron transfer from the proteins to the flavin, as shown by the decrease of the triplet RF band with the concomitant increase of the band of its semireduced form. Tryptophan loss on RF-sensitized photooxidation of the crystallins when irradiated with monochromatic visible light (450 nm) in a 5% oxygen atmosphere was studied. A direct correlation was found between the triplet RF quenching rate constants by the different crystallin fractions and the decomposition rate constants for the exposed and partially buried tryptophans in the proteins. The RF-sensitized photooxidation of the crystallins is accompanied by the decrease of the low molecular weight constituents giving rise to its multimeric forms. A direct correlation was observed between the initial rate of decrease of the low molecular weight bands corresponding to the irradiated alpha-, betaH- and betaL-crystallins and the quenching constant values of triplet RF by the different crystallins. The correlations found in this study confirm the importance of the Type-I photosensitizing mechanism of the crystallins, when RF acts as a sensitizer at low oxygen concentration, as can occur in the eye lens.
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Affiliation(s)
- Gabriela Viteri
- Facultad de Química, Pontificia Universidad Católica de Chile, Santiago, Chile
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42
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Shin YGK, Newton MD, Isied SS. Distance dependence of electron transfer across peptides with different secondary structures: the role of Peptide energetics and electronic coupling. J Am Chem Soc 2003; 125:3722-32. [PMID: 12656602 DOI: 10.1021/ja020358q] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The charge-transfer transition energies and the electronic-coupling matrix element, |H(DA)|, for electron transfer from aminopyridine (ap) to the 4-carbonyl-2,2'-bipyridine (cbpy) in cbpy-(gly)(n)-ap (gly = glycine, n = 0-6) molecules were calculated using the Zerner's INDO/S, together with the Cave and Newton methods. The oligopeptide linkages used were those of the idealized protein secondary structures, the alpha-helix, 3(10)-helix, beta-strand, and polyproline I- and II-helices. The charge-transfer transition energies are influenced by the magnitude and direction of the dipole generated by the peptide secondary structure. The electronic coupling |H(DA)| between (cbpy) and (ap) is also dependent on the nature of the secondary structure of the peptide. A plot of 2.ln|H(DA)| versus the charge-transfer distance (assumed to be the dipole moment change between the ground state and the charge-transfer states) showed that the polyproline II structure is a more efficient bridge for long-distance electron-transfer reactions (beta = 0.7 A(-1)) than the other secondary structures (beta approximately 1.3 A(-1)). Similar calculations on charged dipeptide derivatives, [CH(3)CONHCH(2)CONHCH(3)](+/)(-), showed that peptide-peptide interaction is more dependent on conformation in the cationic than in the anionic dipeptides. The alpha-helix and polyproline II-helix both have large peptide-peptide interactions (|H(DA)| > 800 cm(-1)) which arise from the angular dependence of their pi-orbitals. Such an interaction is much weaker than in the beta-strand peptides. These combined results were found to be consistent with electron-transfer rates experimentally observed across short peptide bridges in polyproline II (n = 1-3). These results can also account for directional electron transfer observed in an alpha-helical structure (different ET rates versus the direction of the molecular dipole).
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Affiliation(s)
- Yeung-gyo K Shin
- Department of Chemistry, Rutgers, the State University of New Jersey, Piscataway 08855, USA
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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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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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45
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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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Abstract
BACKGROUND Exposure of biomacromolecules to ionising radiation results in damage that is initiated by free radicals and progresses through a variety of mechanisms. A widely used technique to study the three-dimensional structures of biomacromolecules is crystallography, which makes use of ionising X-rays. It is crucial to know to what extent structures determined using this technique might be biased by the inherent radiation damage. RESULTS The consequences of radiation damage have been investigated for three dissimilar proteins. Similar results were obtained for each protein, atomic B factors increase, unit-cell volumes increase, protein molecules undergo slight rotations and translations, disulphide bonds break and decarboxylation of acidic residues occurs. All of these effects introduce non-isomorphism. The absorbed dose in these experiments can be reached during routine data collection at undulator beamlines of third generation synchrotron sources. CONCLUSIONS X-rays can leave a 'fingerprint' on structures, even at cryogenic temperatures. Serious non-isomorphism can be introduced, thus hampering multiple isomorphous replacement (MIR) and multiwavelength anomalous dispersion (MAD) phasing methods. Specific structural changes can occur before the traditional measures of radiation damage have signalled it. Care must be taken when assigning structural significance to features that might easily be radiation-damage-induced changes. It is proposed that the electron-affinic disulphide bond traps electrons that migrate over the backbone of the protein, and that the sidechains of glutamic acid and aspartic acid donate electrons to nearby electron holes and become decarboxylated successively. The different disulphide bonds in each protein show a clear order of susceptibility, which might well relate to their intrinsic stability.
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Affiliation(s)
- R B Ravelli
- EMBL Grenoble outstation, Grenoble, BP 156, 38042, 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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