1
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Savina ED, Tsentalovich YP, Sherin PS. Influence of viscosity on mechanism and products of radical reactions of kynurenic acid and tryptophan. Russ Chem Bull 2022. [DOI: 10.1007/s11172-021-3350-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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2
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Hipper E, Blech M, Hinderberger D, Garidel P, Kaiser W. Photo-Oxidation of Therapeutic Protein Formulations: From Radical Formation to Analytical Techniques. Pharmaceutics 2021; 14:72. [PMID: 35056968 PMCID: PMC8779573 DOI: 10.3390/pharmaceutics14010072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 12/09/2021] [Accepted: 12/14/2021] [Indexed: 12/25/2022] Open
Abstract
UV and ambient light-induced modifications and related degradation of therapeutic proteins are observed during manufacturing and storage. Therefore, to ensure product quality, protein formulations need to be analyzed with respect to photo-degradation processes and eventually protected from light exposure. This task usually demands the application and combination of various analytical methods. This review addresses analytical aspects of investigating photo-oxidation products and related mediators such as reactive oxygen species generated via UV and ambient light with well-established and novel techniques.
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Affiliation(s)
- Elena Hipper
- Institute of Chemistry, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany; (E.H.); (D.H.)
| | - Michaela Blech
- Boehringer Ingelheim Pharma GmbH & Co. KG, Innovation Unit, PDB, Birkendorfer Strasse 65, 88397 Biberach an der Riss, Germany;
| | - Dariush Hinderberger
- Institute of Chemistry, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany; (E.H.); (D.H.)
| | - Patrick Garidel
- Boehringer Ingelheim Pharma GmbH & Co. KG, Innovation Unit, PDB, Birkendorfer Strasse 65, 88397 Biberach an der Riss, Germany;
| | - Wolfgang Kaiser
- Boehringer Ingelheim Pharma GmbH & Co. KG, Innovation Unit, PDB, Birkendorfer Strasse 65, 88397 Biberach an der Riss, Germany;
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3
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Fuentes-Lemus E, Hägglund P, López-Alarcón C, Davies MJ. Oxidative Crosslinking of Peptides and Proteins: Mechanisms of Formation, Detection, Characterization and Quantification. Molecules 2021; 27:15. [PMID: 35011250 PMCID: PMC8746199 DOI: 10.3390/molecules27010015] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/17/2021] [Accepted: 12/18/2021] [Indexed: 12/14/2022] Open
Abstract
Covalent crosslinks within or between proteins play a key role in determining the structure and function of proteins. Some of these are formed intentionally by either enzymatic or molecular reactions and are critical to normal physiological function. Others are generated as a consequence of exposure to oxidants (radicals, excited states or two-electron species) and other endogenous or external stimuli, or as a result of the actions of a number of enzymes (e.g., oxidases and peroxidases). Increasing evidence indicates that the accumulation of unwanted crosslinks, as is seen in ageing and multiple pathologies, has adverse effects on biological function. In this article, we review the spectrum of crosslinks, both reducible and non-reducible, currently known to be formed on proteins; the mechanisms of their formation; and experimental approaches to the detection, identification and characterization of these species.
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Affiliation(s)
- Eduardo Fuentes-Lemus
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, 2200 Copenhagen, Denmark; (E.F.-L.); (P.H.)
| | - Per Hägglund
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, 2200 Copenhagen, Denmark; (E.F.-L.); (P.H.)
| | - Camilo López-Alarcón
- Departamento de Química Física, Facultad de Química y de Farmacia, Pontificia Universidad Catolica de Chile, Santiago 7820436, Chile;
| | - Michael J. Davies
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, 2200 Copenhagen, Denmark; (E.F.-L.); (P.H.)
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4
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Sherin PS, Vyšniauskas A, López-Duarte I, Ogilby PR, Kuimova MK. Visualising UV-A light-induced damage to plasma membranes of eye lens. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2021; 225:112346. [PMID: 34736070 DOI: 10.1016/j.jphotobiol.2021.112346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 10/01/2021] [Accepted: 10/19/2021] [Indexed: 01/16/2023]
Abstract
An eye lens is constantly exposed to the solar UV radiation, which is considered the most important external source of age-related changes to eye lens constituents. The accumulation of modifications of proteins and lipids with age can eventually lead to the development of progressive lens opacifications, such as cataracts. Though the impact of solar UV radiation on the structure and function of proteins is actively studied, little is known about the effect of photodamage on plasma membranes of lens cells. In this work we exploit Fluorescence Lifetime Imaging Microscopy (FLIM), together with viscosity-sensitive fluorophores termed molecular rotors, to study the changes in viscosity of plasma membranes of porcine eye lens resulting from two different types of photodamage: Type I (electron transfer) and Type II (singlet oxygen) reactions. We demonstrate that these two types of photodamage result in clearly distinct changes in viscosity - a decrease in the case of Type I damage and an increase in the case of Type II processes. Finally, to simulate age-related changes that occur in vivo, we expose an intact eye lens to UV-A light under anaerobic conditions. The observed decrease in viscosity within plasma membranes is consistent with the ability of eye lens constituents to sensitize Type I photodamage under natural irradiation conditions. These changes are likely to alter the transport of metabolites and predispose the whole tissue to the development of pathological processes such as cataracts.
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Affiliation(s)
- Peter S Sherin
- Chemistry Department, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, London W12 0BZ, UK; International Tomography Center SB RAS, Institutskaya street 3A, Novosibirsk 630090, Russia.
| | - Aurimas Vyšniauskas
- Center for Physical Sciences and Technology, Saulėtekio av. 3, Vilnius LT-10257, Lithuania; Chemistry Department, Vilnius University, Naugarduko st. 24, Vilnius LT-03225, Lithuania
| | - Ismael López-Duarte
- Chemistry Department, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, London W12 0BZ, UK
| | - Peter R Ogilby
- Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus DK-8000, Denmark
| | - Marina K Kuimova
- Chemistry Department, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, London W12 0BZ, UK.
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5
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Demasi M, Augusto O, Bechara EJH, Bicev RN, Cerqueira FM, da Cunha FM, Denicola A, Gomes F, Miyamoto S, Netto LES, Randall LM, Stevani CV, Thomson L. Oxidative Modification of Proteins: From Damage to Catalysis, Signaling, and Beyond. Antioxid Redox Signal 2021; 35:1016-1080. [PMID: 33726509 DOI: 10.1089/ars.2020.8176] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Significance: The systematic investigation of oxidative modification of proteins by reactive oxygen species started in 1980. Later, it was shown that reactive nitrogen species could also modify proteins. Some protein oxidative modifications promote loss of protein function, cleavage or aggregation, and some result in proteo-toxicity and cellular homeostasis disruption. Recent Advances: Previously, protein oxidation was associated exclusively to damage. However, not all oxidative modifications are necessarily associated with damage, as with Met and Cys protein residue oxidation. In these cases, redox state changes can alter protein structure, catalytic function, and signaling processes in response to metabolic and/or environmental alterations. This review aims to integrate the present knowledge on redox modifications of proteins with their fate and role in redox signaling and human pathological conditions. Critical Issues: It is hypothesized that protein oxidation participates in the development and progression of many pathological conditions. However, no quantitative data have been correlated with specific oxidized proteins or the progression or severity of pathological conditions. Hence, the comprehension of the mechanisms underlying these modifications, their importance in human pathologies, and the fate of the modified proteins is of clinical relevance. Future Directions: We discuss new tools to cope with protein oxidation and suggest new approaches for integrating knowledge about protein oxidation and redox processes with human pathophysiological conditions. Antioxid. Redox Signal. 35, 1016-1080.
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Affiliation(s)
- Marilene Demasi
- Laboratório de Bioquímica e Biofísica, Instituto Butantan, São Paulo, Brazil
| | - Ohara Augusto
- Departamento de Bioquímica and Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Etelvino J H Bechara
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Renata N Bicev
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Fernanda M Cerqueira
- CENTD, Centre of Excellence in New Target Discovery, Instituto Butantan, São Paulo, Brazil
| | - Fernanda M da Cunha
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Ana Denicola
- Laboratorios Fisicoquímica Biológica-Enzimología, Facultad de Ciencias, Instituto de Química Biológica, Universidad de la República, Montevideo, Uruguay
| | - Fernando Gomes
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Sayuri Miyamoto
- Departamento de Bioquímica and Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Luis E S Netto
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Lía M Randall
- Laboratorios Fisicoquímica Biológica-Enzimología, Facultad de Ciencias, Instituto de Química Biológica, Universidad de la República, Montevideo, Uruguay
| | - Cassius V Stevani
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Leonor Thomson
- Laboratorios Fisicoquímica Biológica-Enzimología, Facultad de Ciencias, Instituto de Química Biológica, Universidad de la República, Montevideo, Uruguay
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6
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Morozova OB, Yurkovskaya AV, Sherin PS. Kynurenic acid and its chromophoric core 4-hydroxyquinoline react with tryptophan via proton-coupled electron transfer, and with tyrosine via H-transfer. Phys Chem Chem Phys 2021; 23:22483-22491. [PMID: 34586113 DOI: 10.1039/d1cp03496k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Kynurenic acid (KNA) and 4-hydroxyquinoline (4HQN) are photochemically active products of tryptophan catabolism that readily react with tryptophan (Trp) and tyrosine (Tyr) after optical excitation. Recently, transient absorption experiments have shown that at neutral pH Trp reacts with triplet KNA via proton-coupled electron transfer (PCET), and not via electron transfer (ET) as it was suggested before. PCET includes the stepwise transition of both electrons and protons from Trp to triplet KNA. In this work, we confirmed that PCET is the reaction mechanism by the alternative method of time-resolved chemically induced dynamic nuclear polarization (TR-CIDNP). Further studies by TR-CIDNP revealed hydrogen transfer as the mechanism of the reaction between triplet KNA and Tyr in neutral solutions and a transition of both PCET and H-transfer mechanisms to ET under acidic conditions. 4HQN, being the chromophoric core of KNA, exhibits different spectral and photophysical properties from KNA but employs the same mechanisms for the reactions of its triplet state with Trp and Tyr at neutral and acidic pH.
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Affiliation(s)
- Olga B Morozova
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia.
| | | | - Peter S Sherin
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia.
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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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Osik NA, Zelentsova EA, Tsentalovich YP. Kinetic Studies of Antioxidant Properties of Ovothiol A. Antioxidants (Basel) 2021; 10:antiox10091470. [PMID: 34573105 PMCID: PMC8470380 DOI: 10.3390/antiox10091470] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 02/01/2023] Open
Abstract
Ovothiol A (OSH) is one of the strongest natural antioxidants. So far, its presence was found in tissues of marine invertebrates, algae and fish. Due to very low pKa value of the SH group, under physiological conditions, this compound is almost entirely present in chemically active thiolate form and reacts with ROS and radicals significantly faster than other natural thiols. In biological systems, OSH acts in tandem with glutathione GSH, with OSH neutralizing oxidants and GSH maintaining ovothiol in the reduced state. In the present work, we report the rate constants of OSH oxidation by H2O2 and of reduction of oxidized ovothiol OSSO by GSH and we estimate the Arrhenius parameters for these rate constants. The absorption spectra of reaction intermediates, adduct OSSG and sulfenic acid OSOH, were obtained. We also found that OSH effectively quenches the triplet state of kynurenic acid with an almost diffusion-controlled rate constant. This finding indicates that OSH may serve as a good photoprotector to inhibit the deleterious effect of solar UV irradiation; this assumption explains the high concentrations of OSH in the fish lens. The unique antioxidant and photoprotecting properties of OSH open promising perspectives for its use in the treatment of human diseases.
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Affiliation(s)
- Nataliya A. Osik
- International Tomography Center SB RAS, Institutskaya 3a, 630090 Novosibirsk, Russia; (N.A.O.); (E.A.Z.)
- Physical Department, Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia
| | - Ekaterina A. Zelentsova
- International Tomography Center SB RAS, Institutskaya 3a, 630090 Novosibirsk, Russia; (N.A.O.); (E.A.Z.)
- Physical Department, Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia
| | - Yuri P. Tsentalovich
- International Tomography Center SB RAS, Institutskaya 3a, 630090 Novosibirsk, Russia; (N.A.O.); (E.A.Z.)
- Physical Department, Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia
- Correspondence:
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9
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Zhuravleva YS, Sherin PS. Influence of pH on radical reactions between kynurenic acid and amino acids tryptophan and tyrosine. Part I. Amino acids in free state. Free Radic Biol Med 2021; 172:331-339. [PMID: 34146664 DOI: 10.1016/j.freeradbiomed.2021.06.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 06/14/2021] [Indexed: 01/06/2023]
Abstract
In the human eye lens the endogenous chromophores of UV-A light (315-400 nm) are able to sensitize radical reactions leading to protein modifications during normal aging and the cataract progression. Kynurenic acid (KNA-) is the most photochemically active dye of the human eye lens reported to date with pKa(KNAH2•) 5.5 for its radical form. Cataract is thought to develop under oxidative stress which could be accompanied by acidosis, an acidification of the intracellular environment. Protonation of kynurenyl radicals at mildly acidic conditions may change the outcome of radical reactions leading to additional damage to proteins. In this work we investigated the influence of pH on the degradation of initial reagents and the formation of products in photoinduced radical reactions between KNA- and amino acids tryptophan (Trp) and tyrosine (Tyr) in free states. Our results have shown that pH variation has minor influence on kinetics of reagent decay and accumulation of products in reactions between tyrosyl and kynurenic acid radicals. However in the case of Trp a two-fold decrease of the reagent degradation without visible changes in the composition of formed products was observed with pH decrease from 7 to 3. Time-resolved measurements have shown similar acidification-induced two-fold acceleration of decay of kynurenyl and tryptophanyl radicals via Back Electron Transfer (BET) with the restoration of initial reagents. Experiments with tryptophan derivatives with different pKa values for their radical forms point out the protonation of tryptophanyl radical as the driving force for BET acceleration at low pH. Our results demonstrate that the protonation of kynurenyl radical does not change its reactivity towards amino acids radicals but the total yield of radical photodamage decreases with the protonation of tryptophanyl radicals. It could be expected that radical induced damage to proteins will depend on the pKa of tryptophanyl radicals within a protein globule.
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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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10
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Paviani V, Junqueira de Melo P, Avakin A, Di Mascio P, Ronsein GE, Augusto O. Human cataractous lenses contain cross-links produced by crystallin-derived tryptophanyl and tyrosyl radicals. Free Radic Biol Med 2020; 160:356-367. [PMID: 32858158 DOI: 10.1016/j.freeradbiomed.2020.08.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 08/19/2020] [Indexed: 01/13/2023]
Abstract
Protein insolubilization, cross-linking and aggregation are considered critical to the development of lens opacity in cataract. However, the information about the presence of cross-links other than disulfides in cataractous lenses is limited. A potential role for cross-links produced from tryptophanyl radicals in cataract development is suggested by the abundance of the UV light-sensitive Trp residues in crystallin proteins. Here we developed a LC-MS/MS approach to examine the presence of Trp-Trp, Trp-Tyr and Tyr-Tyr cross-links and of peptides containing Trp-2H (-2.0156 Da) in the lens of three patients diagnosed with advanced nuclear cataract. In the proteins of two of the lenses, we characterized intermolecular cross-links between βB2-Tyr153-Tyr104-βA3 and βB2-Trp150-Tyr139-βS. An additional intermolecular cross-link (βB2-Tyr61-Trp200-βB3) was present in the lens of the oldest patient. In the proteins of all three lenses, we characterized two intramolecular Trp-Trp cross-links (Trp123-Trp126 in βB1 and Trp81-Trp84 in βB2) and six peptides containing Trp -2H residues, which indicate the presence of additional Trp-Trp cross-links. Relevantly, we showed that similar cross-links and peptides with modified Trp-2H residues are produced in a time-dependent manner in bovine β-crystallin irradiated with a solar simulator. Therefore, different crystallin proteins cross-linked by crystalline-derived tryptophanyl and tyrosyl radicals are present in advanced nuclear cataract lenses and similar protein modifications can be promoted by solar irradiation even in the absence of photosensitizers. Overall, the results indicate that a role for Trp-Tyr and Trp-Trp cross-links in the development of human cataract is possible and deserves further investigation.
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Affiliation(s)
- Verônica Paviani
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, 05508-000, São Paulo, Brazil
| | - Paulo Junqueira de Melo
- Hospital Das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar 255, 05403-000, São Paulo, Brazil
| | - Amaryllis Avakin
- Hospital Das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar 255, 05403-000, São Paulo, Brazil
| | - Paolo Di Mascio
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, 05508-000, São Paulo, Brazil
| | - Graziella Eliza Ronsein
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, 05508-000, São Paulo, Brazil.
| | - Ohara Augusto
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, 05508-000, São Paulo, Brazil.
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11
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Bellmaine S, Schnellbaecher A, Zimmer A. Reactivity and degradation products of tryptophan in solution and proteins. Free Radic Biol Med 2020; 160:696-718. [PMID: 32911085 DOI: 10.1016/j.freeradbiomed.2020.09.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 08/06/2020] [Accepted: 09/02/2020] [Indexed: 12/13/2022]
Abstract
Tryptophan is one of the essential mammalian amino acids and is thus a required component in human nutrition, animal feeds, and cell culture media. However, this aromatic amino acid is highly susceptible to oxidation and is known to degrade into multiple products during manufacturing, storage, and processing. Many physical and chemical processes contribute to the degradation of this compound, primarily via oxidation or cleavage of the highly reactive indole ring. The central contributing factors are reactive oxygen species, such as singlet oxygen, hydrogen peroxide, and hydroxyl radicals; light and photosensitizers; metals; and heat. In a multi-component mixture, tryptophan also commonly reacts with carbonyl-containing compounds, leading to a wide variety of products. The purpose of this review is to summarize the current state of knowledge regarding the degradation and interaction products of tryptophan in complex liquid solutions and in proteins. For the purposes of context, a brief summary of the key pathways in tryptophan metabolism will be included, along with common methods and issues in tryptophan manufacturing. The review will focus on the conditions that lead to tryptophan degradation, the products generated in these processes, their known biological effects, and methods which may be applied to stabilize the amino acid.
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Affiliation(s)
- Stephanie Bellmaine
- Merck Life Science, Upstream R&D, Frankfurter Strasse 250, 64293, Darmstadt, Germany
| | - Alisa Schnellbaecher
- Merck Life Science, Upstream R&D, Frankfurter Strasse 250, 64293, Darmstadt, Germany
| | - Aline Zimmer
- Merck Life Science, Upstream R&D, Frankfurter Strasse 250, 64293, Darmstadt, Germany.
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12
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Zhuravleva YS, Morozova OB, Tsentalovich YP, Sherin PS. Proton-coupled electron transfer as the mechanism of reaction between triplet state of kynurenic acid and tryptophan. J Photochem Photobiol A Chem 2020. [DOI: 10.1016/j.jphotochem.2020.112522] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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13
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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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14
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Figueroa JD, Zárate AM, Fuentes-Lemus E, Davies MJ, López-Alarcón C. Formation and characterization of crosslinks, including Tyr–Trp species, on one electron oxidation of free Tyr and Trp residues by carbonate radical anion. RSC Adv 2020; 10:25786-25800. [PMID: 35518626 PMCID: PMC9055361 DOI: 10.1039/d0ra04051g] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 06/28/2020] [Indexed: 01/04/2023] Open
Abstract
Dityrosine and ditryptophan bonds have been implied in protein crosslinking. This is associated with oxidative stress conditions including those involved in neurodegenerative pathologies and age-related processes. Formation of dityrosine and ditryptophan derives from radical–radical reactions involving Tyr˙ and Trp˙ radicals. However, cross reactions of Tyr˙ and Trp˙ leading to Tyr–Trp crosslinks and their biological consequences have been less explored. In the present work we hypothesized that exposure of free Tyr and Trp to a high concentration of carbonate anion radicals (CO3˙−), under anaerobic conditions, would result in the formation of Tyr–Trp species, as well as dityrosine and ditryptophan crosslinks. Here we report a simple experimental procedure, employing CO3˙− generated photochemically by illumination of a Co(iii) complex at 254 nm, that produces micromolar concentrations of Tyr–Trp crosslinks. Analysis by mass spectrometry of solutions containing only the individual amino acids, and the Co(iii) complex, provided evidence for the formation of o,o′-dityrosine and isodityrosine from Tyr, and three ditryptophan dimers from Trp. When mixtures of Tyr and Trp were illuminated in an identical manner, Tyr–Trp crosslinks were detected together with dityrosine and ditryptophan dimers. These results indicate that there is a balance between the formation of these three classes of crosslinks, which is dependent on the Tyr and Trp concentrations. The methods reported here allow the generation of significant yields of isolated Tyr–Trp adducts and their characterization. This technology should facilitate the detection, and examination of the biological consequences of Tyr–Trp crosslink formation in complex systems in future investigations. Exposure of free Tyr and Trp to a high concentration of carbonate anion radicals (CO3˙−), under anaerobic conditions, result in the formation of Tyr–Trp species, as well as dityrosine and ditryptophan crosslinks.![]()
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Affiliation(s)
- Juan David Figueroa
- Pontificia Universidad Católica de Chile, Facultad de Química y de Farmacia
- Departamento de Química Física
- Santiago
- Chile
| | - Ana María Zárate
- Pontificia Universidad Católica de Chile, Facultad de Química y de Farmacia
- Departamento de Química Física
- Santiago
- Chile
| | - Eduardo Fuentes-Lemus
- 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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15
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Morozova OB, Sherin PS, Yurkovskaya AV. Competition of singlet and triplet recombination of radical pairs in photoreactions of carboxy benzophenones and aromatic amino acids. Phys Chem Chem Phys 2019; 21:2017-2028. [PMID: 30633277 DOI: 10.1039/c8cp06760k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Time-resolved chemically induced dynamic nuclear polarization (CIDNP) and transient absorption (TA) were applied to reveal the branching ratio of the singlet and triplet recombination channels in the reaction of short-lived radicals of carboxy benzophenones and the aromatic amino acids histidine, tryptophan, and tyrosine in neutral aqueous solution. It was established that the share of triplet recombination increases with increasing number of carboxylic groups: no triplet recombination was found for 4-carboxy benzophenone, whereas ∼13% of radicals of 4,4'-dicarboxy benzophenone (DCBP) and ∼27% of radicals of 3,3',4,4'-tetracarboxy benzophenone (TCBP) react with histidine radicals from the triplet state of radical pairs. The main idea is that the protonated (π,π*) triplet state of TCBP or DCBP is populated via back electron transfer from the ketyl radical of TCBP or DCBP to the radical of the amino acid. The protonated triplet state of the ketone decays with the formation of a metastable hydroxylated product, which is detected by TA. Taking into account triplet recombination provides excellent coincidence between experimental data and the simulated CIDNP kinetics.
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Affiliation(s)
- Olga B Morozova
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia.
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16
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Xu L, Qiu WX, Liu WL, Zhang C, Zou MZ, Sun YX, Zhang XZ. PLA–PEG Micelles Loaded with a Classic Vasodilator for Oxidative Cataract Prevention. ACS Biomater Sci Eng 2019; 5:407-412. [DOI: 10.1021/acsbiomaterials.8b01089] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Lu Xu
- Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry, Wuhan University, Wuhan 430072, People’s Republic of China
| | - Wen-Xiu Qiu
- Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry, Wuhan University, Wuhan 430072, People’s Republic of China
| | - Wen-Long Liu
- Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry, Wuhan University, Wuhan 430072, People’s Republic of China
| | - Chi Zhang
- Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry, Wuhan University, Wuhan 430072, People’s Republic of China
| | - Mei-Zhen Zou
- Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry, Wuhan University, Wuhan 430072, People’s Republic of China
| | - Yun-Xia Sun
- Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry, Wuhan University, Wuhan 430072, People’s Republic of China
| | - Xian-Zheng Zhang
- Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry, Wuhan University, Wuhan 430072, People’s Republic of China
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17
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Zhuravleva YS, Tsentalovich YP. Acid-alkaline properties of triplet state and radical of kynurenic acid. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2018.07.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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18
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Hägglund P, Mariotti M, Davies MJ. Identification and characterization of protein cross-links induced by oxidative reactions. Expert Rev Proteomics 2018; 15:665-681. [DOI: 10.1080/14789450.2018.1509710] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Per Hägglund
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Michele Mariotti
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Michael J. Davies
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, Denmark
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19
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Carroll L, Pattison DI, Davies JB, Anderson RF, Lopez-Alarcon C, Davies MJ. Superoxide radicals react with peptide-derived tryptophan radicals with very high rate constants to give hydroperoxides as major products. Free Radic Biol Med 2018; 118:126-136. [PMID: 29496618 DOI: 10.1016/j.freeradbiomed.2018.02.033] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 02/22/2018] [Accepted: 02/23/2018] [Indexed: 11/23/2022]
Abstract
Oxidative damage is a common process in many biological systems and proteins are major targets for damage due to their high abundance and very high rate constants for reaction with many oxidants (both radicals and two-electron species). Tryptophan (Trp) residues on peptides and proteins are a major sink for a large range of biological oxidants as these side-chains have low radical reduction potentials. The resulting Trp-derived indolyl radicals (Trp•) have long lifetimes in some circumstances due to their delocalized structures, and undergo only slow reaction with molecular oxygen, unlike most other biological radicals. In contrast, we have shown previously that Trp• undergo rapid dimerization. In the current study, we show that Trp• also undergo very fast reaction with superoxide radicals, O2•-, with k 1-2 × 109 M-1 s-1. These values do not alter dramatically with peptide structure, but the values of k correlate with overall peptide positive charge, consistent with positive electrostatic interactions. These reactions compete favourably with Trp• dimerization and O2 addition, indicating that this may be a major fate in some circumstances. The Trp• + O2•- reactions occur primarily by addition, rather than electron transfer, with this resulting in high yields of Trp-derived hydroperoxides. Subsequent degradation of these species, both stimulated and native decay, gives rise to N-formylkynurenine, kynurenine, alcohols and diols. These data indicate that reaction of O2•- with Trp• should be considered as a major pathway to Trp degradation on peptides and proteins subjected to oxidative damage.
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Affiliation(s)
- Luke Carroll
- The Heart Research Institute, Sydney, Australia; Sydney Medical School, University of Sydney, Australia; Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - David I Pattison
- The Heart Research Institute, Sydney, Australia; Sydney Medical School, University of Sydney, Australia
| | - Justin B Davies
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
| | - Robert F Anderson
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand
| | - Camilo Lopez-Alarcon
- Departmento de Quimica Fisica, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Chile
| | - Michael J Davies
- The Heart Research Institute, Sydney, Australia; Sydney Medical School, University of Sydney, Australia; Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark.
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20
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Sherin PS, Tsentalovich YP, Vauthey E, Benassi E. Ultrafast excited state decay of natural UV filters: from intermolecular hydrogen bonds to a conical intersection. Phys Chem Chem Phys 2018; 20:15074-15085. [DOI: 10.1039/c8cp02183j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An unsaturated bond in the side chain leads to the ultrafast decay of the excited statesviaa conical intersection independent of solvent properties.
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Affiliation(s)
- Peter S. Sherin
- International Tomography Center SB RAS
- Novosibirsk
- Russia
- Novosibirsk State University
- Novosibirsk
| | - Yuri P. Tsentalovich
- International Tomography Center SB RAS
- Novosibirsk
- Russia
- Novosibirsk State University
- Novosibirsk
| | - Eric Vauthey
- Department of Physical Chemistry
- University of Geneva
- Geneva
- Switzerland
| | - Enrico Benassi
- Novosibirsk State University
- Novosibirsk
- Russia
- School of Science and Technology
- Nazarbayev University
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21
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Sormacheva ED, Sherin PS, Tsentalovich YP. Dimerization and oxidation of tryptophan in UV-A photolysis sensitized by kynurenic acid. Free Radic Biol Med 2017; 113:372-384. [PMID: 29024806 DOI: 10.1016/j.freeradbiomed.2017.10.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/04/2017] [Accepted: 10/05/2017] [Indexed: 11/24/2022]
Abstract
Photoinduced generation of radicals in the eye lens may play an important role in the modification of proteins leading to their coloration, aggregation, and insolubilization. The radicals can be formed via the reactions of photoexcited endogenous chromophores of the human lens with lens proteins, in particular with tryptophan residues. In the present work we studied the reactions induced by UV-A (315-400nm) light between kynurenic acid (KNA), an effective photosensitizer present in the human lens, and N-acetyl-L-tryptophan (NTrpH) under aerobic and anaerobic conditions. Our results show that the reaction mechanism strongly depends on the presence of oxygen in solution. Under aerobic conditions, the generation of singlet oxygen is the major channel of the effective NTrpH oxidation. In argon-bubbled solutions, the quenching of triplet KNA by NTrpH results in the formation of KNA•- and NTrp• radicals. Under laser pulse irradiation, when the radical concentration is high, the main pathway of the radical decay is the back electron transfer with the restoration of initial reagents. Other reactions include (i) the radical combination yielding NTrp dimers and (ii) the oxygen atom transfer from KNA•- to NTrp• with the formation of oxidized NTrp species and deoxygenated KNA products. In continuous-wave photolysis, even trace amounts of molecular oxygen are sufficient to oxidize the majority of KNA•- radicals with the rate constant of (2.0 ± 0.2) × 109M-1s-1, leading to the restoration of KNA and the formation of superoxide radical O2•-. The latter reacts with NTrp• via either the radical combination to form oxidized NTrp (minor pathway), or the electron transfer to restore NTrpH in the ground state (major pathway). As the result, the quantum yields of the starting compound decomposition under continuous-wave anaerobic photolysis are rather low: 1.6% for NTrpH and 0.02% for KNA. The photolysis of KNA with alpha-crystallin yields the same deoxygenated KNA products as the photolysis of KNA with NTrpH, indicating the similarity of the photolysis mechanisms. Thus, inside the eye lens KNA can sensitize both protein photooxidation and protein covalent cross-linking with the minor self-degradation. This may play an important role in the lens protein modifications during the normal aging and cataract development.
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Affiliation(s)
- Ekaterina D Sormacheva
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090 Novosibisrk, Russia
| | - Peter S Sherin
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090 Novosibisrk, Russia; Novosibirsk State University, Pirogova str. 2, 630090 Novosibisrk, Russia.
| | - Yuri P Tsentalovich
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090 Novosibisrk, Russia; Novosibirsk State University, Pirogova str. 2, 630090 Novosibisrk, Russia
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22
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Carroll L, Pattison DI, Davies JB, Anderson RF, Lopez-Alarcon C, Davies MJ. Formation and detection of oxidant-generated tryptophan dimers in peptides and proteins. Free Radic Biol Med 2017; 113:132-142. [PMID: 28962874 DOI: 10.1016/j.freeradbiomed.2017.09.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 09/21/2017] [Accepted: 09/24/2017] [Indexed: 01/08/2023]
Abstract
Free radicals are produced during physiological processes including metabolism and the immune response, as well as on exposure to multiple external stimuli. Many radicals react rapidly with proteins resulting in side-chain modification, backbone fragmentation, aggregation, and changes in structure and function. Due to its low oxidation potential, the indole ring of tryptophan (Trp) is a major target, with this resulting in the formation of indolyl radicals (Trp•). These undergo multiple reactions including ring opening and dimerization which can result in protein aggregation. The factors that govern Trp• dimerization, the rate constants for these reactions and the exact nature of the products are not fully elucidated. In this study, second-order rate constants were determined for Trp• dimerization in Trp-containing peptides to be 2-6 × 108M-1s-1 by pulse radiolysis. Peptide charge and molecular mass correlated negatively with these rate constants. Exposure of Trp-containing peptides to steady-state radiolysis in the presence of NaN3 resulted in consumption of the parent peptide, and detection by LC-MS of up to 4 different isomeric Trp-Trp cross-links. Similar species were detected with other oxidants, including CO3•- (from the HCO3- -dependent peroxidase activity of bovine superoxide dismutase) and peroxynitrous acid (ONOOH) in the presence or absence of HCO3-. Trp-Trp species were also isolated and detected after alkaline hydrolysis of the oxidized peptides and proteins. These studies demonstrate that Trp• formed on peptides and proteins undergo rapid recombination reactions to form Trp-Trp cross-linked species. These products may serve as markers of radical-mediated protein damage, and represent an additional pathway to protein aggregation in cellular dysfunction and disease.
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Affiliation(s)
- Luke Carroll
- The Heart Research Institute, Newtown, Australia; Sydney Medical School, University of Sydney, Australia; Panum Institute, University of Copenhagen, Denmark
| | - David I Pattison
- The Heart Research Institute, Newtown, Australia; Sydney Medical School, University of Sydney, Australia
| | - Justin B Davies
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
| | | | | | - Michael J Davies
- The Heart Research Institute, Newtown, Australia; Sydney Medical School, University of Sydney, Australia; Panum Institute, University of Copenhagen, Denmark.
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23
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Influence of medium viscosity on photophysical properties of kynurenic acid and kynurenine yellow. Russ Chem Bull 2017. [DOI: 10.1007/s11172-017-1727-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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24
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Zelentsova EA, Yanshole LV, Fursova AZ, Tsentalovich YP. Optical properties of the human lens constituents. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2017. [PMID: 28624737 DOI: 10.1016/j.jphotobiol.2017.06.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The absorption and fluorescence properties of the metabolomic (MET), water-soluble and urea-soluble protein fractions from the middle-age, aged, and cataractous human lenses have been measured. At 280nm and 300nm the major lens absorbers are crystallins, which absorb more than 90% of light in the UV-B region (280-315nm). In middle-aged lenses, the absorption at 360nm is mostly provided by UV filters contained in the MET fraction. With aging, and especially with the cataract development, the absorption of MET fraction in UV-A region (315-400nm) decreases due to the drop of the UV filter concentration, while the absorption of protein fractions increases due to the accumulation of post-translational modifications. Consequently, the contribution of the MET fraction into the total lens absorption at 360nm decays from 63% in middle-aged lenses to 25% in aged lenses to 3% in cataractous lenses. The fluorescence yield of the MET fraction from cataractous lenses also significantly increases. Therefore, the protection of the lens tissue against UV radiation in aged and cataractous lenses weakens: the absorption of UV-A light is mostly provided by modified crystallins and non-UV-filter metabolites, which are photochemically more active than the UV filters. The obtained data indicate that the aged and cataractous human lenses are more vulnerable to UV-A light than the middle-aged lenses.
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Affiliation(s)
- Ekaterina A Zelentsova
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
| | - Lyudmila V Yanshole
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
| | - Anjella Zh Fursova
- Novosibirsk State Regional Clinical Hospital, Nemirovicha-Danchenko 130, Novosibirsk 630087, Russia
| | - Yuri P Tsentalovich
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
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