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Woolley AK, Chudasama Y, Seidu SI, Gillies C, Schreder S, Davies MJ, Khunti K. Influence of sociodemographic characteristics on the preferred format of health education delivery in individuals with type 2 diabetes mellitus and or cardiovascular disease: a questionnaire study. Diabet Med 2020; 37:982-990. [PMID: 32096573 DOI: 10.1111/dme.14275] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/22/2020] [Indexed: 12/27/2022]
Abstract
AIM To examine the influence of sociodemographic factors of interest on preference for a particular health education format among people with type 2 diabetes and/or cardiovascular disease. METHODS A questionnaire was used to collect information on the influence of six sociodemographic factors of interest on the preference for health education formats in people with type 2 diabetes and/or cardiovascular disease. Chi-squared tests were used to examine the distribution of preferences between groups. The characteristics of the population preferring the online format were then examined in more detail using logistic regression. RESULTS Responses were received from 1559 participants. Overall the preferred health education format was one-to-one learning from a doctor or nurse (67%). Age, gender, diagnosis and educational level all affected the preferences expressed. The characteristics showing most consistent and significant influence were age and educational level. Overall, 29% ranked the online format highly (scores 1 or 2). This group were more likely to be aged < 65 years (P < 0.001) and to have a higher level of educational attainment (upper secondary education or higher; P < 0.001). CONCLUSIONS Significant differences between sociodemographic groups exist in preferences for health education formats among people with type 2 diabetes and/or cardiovascular disease. Preferences should be considered when designing educational interventions to ensure they are accessible to the target group and to avoid increases in health inequality.
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Ignasiak M, Frackowiak K, Pedzinski T, Davies MJ, Marciniak B. Unexpected light emission from tyrosyl radicals as a probe for tyrosine oxidation. Free Radic Biol Med 2020; 153:12-16. [PMID: 32304751 DOI: 10.1016/j.freeradbiomed.2020.03.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/05/2020] [Accepted: 03/23/2020] [Indexed: 12/29/2022]
Abstract
Tyrosine residues (Tyr) on proteins are a favoured site of one-electron oxidation due to their low one-electron reduction potentials. In this work, light-induced oxidation of Tyr residues was investigated using direct ionisation (via 266 nm light excitation) and sensitized photo-oxidation (by 3-carboxybenzophenone as sensitizer and 355 nm). Light emission (fluorescence) was observed at 410-440 nm as a result of Tyr oxidation. This novel light emission process is shown to be dependent on the solvent and aromatic ring substituents, however it does not depend on pH. It is proposed, that after initial formation of tyrosine phenoxyl radicals (TyrO●) by one electron-oxidation, the TyrO● absorbs a second photon to give an excited state species that undergoes subsequent light emission. The intensity of this emission depends on the Tyr concentration, and the detection of this emission can be used to identify and quantify one-electron formation of oxidized Tyr residues on proteins.
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Gamon LF, Guo C, He J, Hägglund P, Hawkins CL, Davies MJ. Absolute quantitative analysis of intact and oxidized amino acids by LC-MS without prior derivatization. Redox Biol 2020; 36:101586. [PMID: 32505089 PMCID: PMC7276450 DOI: 10.1016/j.redox.2020.101586] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/11/2020] [Accepted: 05/14/2020] [Indexed: 01/15/2023] Open
Abstract
The precise characterization and quantification of oxidative protein damage is a significant challenge due to the low abundance, large variety, and heterogeneity of modifications. Mass spectrometry (MS)-based techniques at the peptide level (proteomics) provide a detailed but limited picture due to incomplete sequence coverage and imperfect enzymatic digestion. This is particularly problematic with oxidatively modified and cross-linked/aggregated proteins. There is a pressing need for methods that can quantify large numbers of modified amino acids, which are often present in low abundance compared to the high background of non-damaged amino acids, in a rapid and reliable fashion. We have developed a protocol using zwitterionic ion-exchange chromatography coupled with LC-MS to simultaneously quantify both parent amino acids and their respective oxidation products. Proteins are hydrolyzed with methanesulfonic acid in the presence of tryptamine and purified by strong cation exchange solid phase extraction. The method was validated for the common amino acids (excluding Gln, Asn, Cys) and the oxidation products 3-chlorotyrosine (3-ClTyr), 3-nitrotyrosine (3-NO2Tyr), di-tyrosine, Nε-(1-carboxymethyl)-l-lysine, o,o’-di-tyrosine, 3,4,-dihydroxyphenylalanine, hydroxy-tryptophan and kynurenine. Linear standard curves were observed over ~3 orders of magnitude dynamic range (2–1000 pmol for parent amino acids, 80 fmol–20 pmol for oxidation products) with limit-of-quantification values as low as 200 fmol (o,o’-di-tyrosine). The validated method was used to quantify Tyr and Trp loss, and formation of 3-NO2Tyr on the isolated protein anastellin treated with peroxynitrous acid, and for 3-ClTyr formation (over a 2 orders of magnitude range) in cell lysates and complex protein mixtures treated with hypochlorous acid. Identification and quantification of oxidative protein damage is a major challenge. A versatile LC-MS assay is reported that involves hydrolysis to free amino acids. Quantification is possible for both parent amino acids and products in single runs. A dynamic range of 2-3 orders of magnitude is available for most analytes. Example of use with pure proteins, extracellular matrix and cell lysates are given.
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Fuentes-Lemus E, Mariotti M, Reyes J, Leinisch F, Hägglund P, Silva E, Davies MJ, López-Alarcón C. Photo-oxidation of lysozyme triggered by riboflavin is O 2-dependent, occurs via mixed type 1 and type 2 pathways, and results in inactivation, site-specific damage and intra- and inter-molecular crosslinks. Free Radic Biol Med 2020; 152:61-73. [PMID: 32142879 DOI: 10.1016/j.freeradbiomed.2020.03.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/28/2020] [Accepted: 03/02/2020] [Indexed: 12/21/2022]
Abstract
Photosensitized protein oxidation is a promising tool for medical procedures such as photochemical tissue bonding (PTB). We have recently reported that the binding of rose Bengal, a sensitizer employed in PTB, to lysozyme modulates the photooxidation and crosslinking of this protein. In this work we examined the photooxidation and crosslinking of lysozyme mediated by riboflavin (RF) an endogenous sensitizer also employed in PTB. We hypothesized that since RF does not bind strongly to proteins, the mechanism(s) and extent of enzymatic inactivation, amino acid modification and protein crosslinking would be dependent on the presence of O2, and differ to that induced by rose Bengal. This hypothesis was tested using UV-visible spectrophotometry, isothermal titration calorimetry (ITC), SDS-PAGE gels, quantification of amino acid consumption, and LC-MS analysis of sites of modification and crosslinks. Under N2, limited damage was detected arising from type 1 (radical) chemistry with formation of specific intra- (Tyr20-Tyr23) and inter- (Tyr23-Trp108) molecular crosslinks. In contrast, the presence of O2 triggered extensive protein damage through mixed type 1 and type 2 (1O2) mechanisms leading to Trp, Met, Tyr and His oxidation, loss of enzymatic activity and protein dimerization. LC-MS analysis provided evidence for crosslinking via radical-radical recombination reactions (Trp28-Tyr53), and secondary reactions involving nucleophilic attack of the side-chain amine of Lys116 on carbonyl groups. Overall, this behavior is in marked contrast to that detected with rose Bengal indicating that the mechanisms and sites of photo-oxidative damage, and consequences for protein function, can be modulated by the choice of sensitizing dye.
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Baldry EL, Davies MJ, Khunti K, Webb DR. Pragmatic management of low-energy diets in people with type 2 diabetes in primary care: a decision aid for clinicians. Diabet Med 2020; 37:747-751. [PMID: 32020691 DOI: 10.1111/dme.14265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/03/2020] [Indexed: 12/13/2022]
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Davies MJ, Hawkins CL. The Role of Myeloperoxidase in Biomolecule Modification, Chronic Inflammation, and Disease. Antioxid Redox Signal 2020; 32:957-981. [PMID: 31989833 DOI: 10.1089/ars.2020.8030] [Citation(s) in RCA: 149] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Significance: The release of myeloperoxidase (MPO) by activated leukocytes is critical in innate immune responses. MPO produces hypochlorous acid (HOCl) and other strong oxidants, which kill bacteria and other invading pathogens. However, MPO also drives the development of numerous chronic inflammatory pathologies, including atherosclerosis, neurodegenerative disease, lung disease, arthritis, cancer, and kidney disease, which are globally responsible for significant patient mortality and morbidity. Recent Advances: The development of imaging approaches to precisely identify the localization of MPO and the molecular targets of HOCl in vivo is an important advance, as typically the involvement of MPO in inflammatory disease has been inferred by its presence, together with the detection of biomarkers of HOCl, in biological fluids or diseased tissues. This will provide valuable information in regard to the cell types responsible for releasing MPO in vivo, together with new insight into potential therapeutic opportunities. Critical Issues: Although there is little doubt as to the value of MPO inhibition as a protective strategy to mitigate tissue damage during chronic inflammation in experimental models, the impact of long-term inhibition of MPO as a therapeutic strategy for human disease remains uncertain, in light of the potential effects on innate immunity. Future Directions: The development of more targeted MPO inhibitors or a treatment regimen designed to reduce MPO-associated host tissue damage without compromising pathogen killing by the innate immune system is therefore an important future direction. Similarly, a partial MPO inhibition strategy may be sufficient to maintain adequate bacterial activity while decreasing the propagation of inflammatory pathologies.
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Indo HP, Majima HJ, Terada M, Suenaga S, Tomita K, Higashibata A, Ishioka N, Kanekura T, Hawkins CL, Davies MJ, St Clair DK, Mukai C. Author Correction: Changes in mitochondrial homeostasis and redox status in astronauts following long stays in space. Sci Rep 2020; 10:6910. [PMID: 32313147 PMCID: PMC7170886 DOI: 10.1038/s41598-020-63753-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Gentile C, Kesteven S, Wu J, Davies MJ, Bursill C, Feneley M, Figtree G. Endothelial nitric oxide synthase plays a protective role in endothelial cells and cardiomyocytes against myocardial infarction. J Mol Cell Cardiol 2020. [DOI: 10.1016/j.yjmcc.2019.11.072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Zacharias T, Flouda K, Jepps TA, Gammelgaard B, Schiesser CH, Davies MJ. Effects of a novel selenium substituted-sugar (1,4-anhydro-4-seleno-d-talitol, SeTal) on human coronary artery cell lines and mouse aortic rings. Biochem Pharmacol 2020; 173:113631. [DOI: 10.1016/j.bcp.2019.113631] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Accepted: 09/03/2019] [Indexed: 12/17/2022]
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Joish VN, Zhou FL, Preblick R, Lin D, Deshpande M, Verma S, Davies MJ, Paranjape S, Pettus J. Estimation of Annual Health Care Costs for Adults with Type 1 Diabetes in the United States. J Manag Care Spec Pharm 2020; 26:311-318. [PMID: 32105172 PMCID: PMC10390990 DOI: 10.18553/jmcp.2020.26.3.311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Diabetes health care resource utilization (HCRU) studies tend to focus on patients with type 2 diabetes (T2D) or pool patients with T2D and type 1 diabetes (T1D). There is a paucity of recent data on the cost of treating patients with T1D in the United States. OBJECTIVES To (a) estimate the per-patient per-year (PPPY) HCRU and costs, from a payer perspective, associated with treating U.S. adults with T1D and (b) compare these with the HCRU and costs for patients with T2D. METHODS This retrospective cohort study used claims data from the Optum Clinformatics database between January 2015 and December 2017. Adults (aged ≥ 18 years) with a diagnosis of T1D were propensity score-matched to adults with T2D. Overall and nondiabetes-related HCRU and costs were assessed for T1D and T2D and compared between the 2 groups. RESULTS Propensity scores were used to match 10,103 patient pairs from T1D and T2D cohorts (mean ages 54.4 and 56.9 years, respectively). In the T1D cohort, inpatient, emergency department (ED), outpatient, and prescription claims occurred in 14.0%, 17.3%, 85.5%, and 100% of patients, respectively, resulting in a mean total cost of U.S. $18,817 PPPY (diabetes-related = $11,002; nondiabetes-related = $7,816). The T1D cohort had significantly higher mean total costs than the T2D cohort ($18,817 vs. $14,148 PPPY; P < 0.001). When extrapolating these findings to a commercial health plan with 1 million covered lives, the estimated total direct medical costs of T1D would be $103.4 million. CONCLUSIONS This study showed that the total annual cost of managing an adult with T1D is significantly higher than that of an adult with T2D. Nondiabetes costs accounted for 40% of the total per-patient cost, similar to patients with T2D, confirming that as patients with T1D live longer lives, they may also be at greater risk for cardiometabolic complications. DISCLOSURES This study was funded by Sanofi U.S. and Lexicon Pharmaceuticals as part of a business partnership in a diabetes program at the time this study was conducted. Joish and Davies are employees and stockholders of Lexicon Pharmaceuticals. Zhou, Preblick, and Paranjape are employees and stockholders of Sanofi. Lin was a postdoctoral fellow at Sanofi through Rutgers University during this project. Deshpande provided consulting services through Communication Symmetry. Verma is an employee of Evidera, which was contracted by Sanofi for work on this study. Pettus is a consultant for Diasome, Insulet, Lexicon, Lilly, Mannkind, Novo Nordisk, Sanofi, and Senseonics.
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Crasto W, Morrison AE, Gray LJ, John E, Jarvis J, Brela J, Khunti K, Troughton J, Lawrence IG, McNally PG, Davies MJ. The Microalbuminuria Education Medication and Optimisation (MEMO) study: 4 years follow-up of multifactorial intervention in high-risk individuals with type 2 diabetes. Diabet Med 2020; 37:286-297. [PMID: 31505051 DOI: 10.1111/dme.14134] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/05/2019] [Indexed: 11/30/2022]
Abstract
AIMS The Microalbuminuria Education Medication and Optimisation (MEMO) study, revealed improved cardiovascular risk and glycaemic control with 18 months of intensive multifactorial intervention in high-risk people with type 2 diabetes, without any increase in severe hypoglycaemia. Our aim was to assess longer-term outcomes at 4-year follow-up in these participants. METHODS Some 189 individuals with type 2 diabetes and microalbuminuria were recruited from a multi-ethnic population in Leicestershire, UK. The intervention group (n = 95) received multifactorial intervention with self-management education, and the control group (n = 94) received usual care. The primary outcome was change in HbA1c , and secondary outcomes were blood pressure (BP), cholesterol, microalbuminuria, estimated GFR, cardiovascular risk scores and major adverse cardiovascular events. RESULTS Some 130 participants (68.7%), mean (sd) age 60.8 (10.4) years, duration of diabetes 11.5 (9.7) years, completed 4 years of follow-up. Mean change [95% confidence intervals (CI)] in HbA1c over 4 years was greater with intensive intervention compared with control (-3 mmol/mol, 95% CI -4.95,-1.11; -0.4%, 95% CI -0.67,-0.15; P = 0.002). Significant improvements over the 4 years were also seen in systolic BP (-7.3 mmHg, 95% CI -11.1, -3.5; P < 0.001), diastolic BP (-2.9 mmHg, 95% CI -5.4, -0.3; P = 0.026), cholesterol (-0.3 mmol/l, 95% CI -0.52,-0.12; P = 0.002), and 10-year coronary heart disease (-5.3, 95% CI -8.2,-2.3; P < 0.001) and stroke risk (-4.4, 95% CI -7.5, -1.3; P < 0.001). CONCLUSION Multifactorial intervention with structured diabetes self-management education compared with usual diabetes care has benefits for cardio-metabolic risk factor profile. There was no increase in severe hypoglycaemia and cardiovascular mortality despite intensive glycaemic control, although the study was not powered to assess these outcomes.
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Chudasama YV, Zaccardi F, Gillies CL, Dhalwani NN, Yates T, Rowlands AV, Davies MJ, Khunti K. Leisure-time physical activity and life expectancy in people with cardiometabolic multimorbidity and depression. J Intern Med 2020; 287:87-99. [PMID: 31602698 DOI: 10.1111/joim.12987] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Whether and to what extent leisure-time physical activity at the recommended levels of 150-min moderate activity is associated with survival in people with cardiometabolic multimorbidity and depression is unknown. METHODS UK Biobank participants were classified into groups: (i) no disease; (ii) diabetes; (iii) cardiovascular disease (CVD); (iv) depression; (v) diabetes and CVD; (vi) diabetes and depression; (vii) CVD and depression; (viii) diabetes, CVD and depression. Leisure-time physical activity was categorized as active (meeting recommendations) or inactive. Survival models were applied to estimate life expectancy. RESULTS A total of 480 940 participants were included (median age, 58 years; 46% men; 95% white), of whom 74% with cardiometabolic multimorbidity and depression were inactive. During a mean follow-up of 7 years, 11 006 deaths occurred. At age of 45 years, being physically active was associated with 2.34 (95% confidence interval: 0.93, 3.54) additional years of life compared with being inactive in participants with diabetes; corresponding estimates were 2.28 (1.40, 3.16) for CVD; 2.15 (0.05, 4.26) for diabetes and CVD; and 1.58 (1.27, 1.89) for no disease. Participants with a combination of diabetes, CVD and depression, being active was associated with 6.81 (-1.50, 15.31) additional years compared with being inactive; corresponding estimates were 3.07 (-2.46, 8.59) for diabetes and depression; 2.34 (-1.24, 5.91) for CVD and depression; and 0.80 (-0.46, 2.05) for depression. A similar pattern was found at 65 years. CONCLUSIONS Meeting the recommended level of physical activity was associated with a longer life expectancy in people with cardiometabolic multimorbidity but not in those with depression.
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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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Hawkins CL, Davies MJ. Detection, identification, and quantification of oxidative protein modifications. J Biol Chem 2019; 294:19683-19708. [PMID: 31672919 PMCID: PMC6926449 DOI: 10.1074/jbc.rev119.006217] [Citation(s) in RCA: 205] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Exposure of biological molecules to oxidants is inevitable and therefore commonplace. Oxidative stress in cells arises from both external agents and endogenous processes that generate reactive species, either purposely (e.g. during pathogen killing or enzymatic reactions) or accidentally (e.g. exposure to radiation, pollutants, drugs, or chemicals). As proteins are highly abundant and react rapidly with many oxidants, they are highly susceptible to, and major targets of, oxidative damage. This can result in changes to protein structure, function, and turnover and to loss or (occasional) gain of activity. Accumulation of oxidatively-modified proteins, due to either increased generation or decreased removal, has been associated with both aging and multiple diseases. Different oxidants generate a broad, and sometimes characteristic, spectrum of post-translational modifications. The kinetics (rates) of damage formation also vary dramatically. There is a pressing need for reliable and robust methods that can detect, identify, and quantify the products formed on amino acids, peptides, and proteins, especially in complex systems. This review summarizes several advances in our understanding of this complex chemistry and highlights methods that are available to detect oxidative modifications-at the amino acid, peptide, or protein level-and their nature, quantity, and position within a peptide sequence. Although considerable progress has been made in the development and application of new techniques, it is clear that further development is required to fully assess the relative importance of protein oxidation and to determine whether an oxidation is a cause, or merely a consequence, of injurious processes.
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Shu N, Hägglund P, Cai H, Hawkins CL, Davies MJ. Modification of Cys residues in human thioredoxin-1 by p-benzoquinone causes inhibition of its catalytic activity and activation of the ASK1/p38-MAPK signalling pathway. Redox Biol 2019; 29:101400. [PMID: 31926625 PMCID: PMC6926358 DOI: 10.1016/j.redox.2019.101400] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 12/04/2019] [Accepted: 12/05/2019] [Indexed: 01/27/2023] Open
Abstract
Quinones can modify biological molecules through both redox-cycling reactions that yield radicals (semiquinone, superoxide and hydroxyl) and via covalent adduction to nucleophiles (e.g. thiols and amines). Kinetic data indicate that Cys residues in GSH and proteins are major targets. In the studies reported here, the interactions of a prototypic quinone compound, p-benzoquinone (BQ), with the key redox protein, thioredoxin-1 (Trx1) were examined. BQ binds covalently with isolated Trx1 forming quinoprotein adducts, resulting in a concentration-dependent loss of enzyme activity and crosslink formation. Mass spectrometry peptide mass mapping data indicate that BQ forms adducts with all of the Trx1 Cys residues. Glutathione (GSH) reacts competitively with BQ, and thereby modulates the loss of activity and crosslink formation. Exposure of macrophage-like (J774A.1) cells to BQ results in a dose-dependent loss of Trx and thioredoxin reductase (TrxR) activities, quinoprotein formation, and a decrease in GSH levels without a concomitant increase in oxidized glutathione. GSH depletion aggravates the loss of Trx and TrxR activity. These data are consistent with adduction of GSH to BQ being a primary protective pathway. Reaction of BQ with Trx in cells resulted in the activation of apoptosis signal-regulating kinase 1 (ASK1), and p38 mitogen-activated protein kinase (MAPK) leading to apoptotic cell death. These data suggest that BQ reacts covalently with Cys residues in Trx, including at the active site, leading to enzyme inactivation and protein cross-linking. Modification of the Cys residues in Trx also results in activation of the ASK1/p38-MAPK signalling pathway and promotion of apoptotic cell death. Quinone (e.g. p-benzoquinone, BQ) toxicity is linked to Michael adduction reactions. Adduction of BQ to Cys residues in proteins are rapid (≤105 M−1 s−1) and selective. BQ reaction with Cys inactivates thioredoxin (Trx) and yields quinone- and disulfide-linked dimers. GSH reacts competitively with BQ and modulates damage, without GSSG formation. BQ activates ASK1 and p38 pathways and induced apoptosis in cells via Trx damage.
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Perrin N, Bodicoat DH, Davies MJ, Robertson N, Snoek FJ, Khunti K. Effectiveness of psychoeducational interventions for the treatment of diabetes-specific emotional distress and glycaemic control in people with type 2 diabetes: A systematic review and meta-analysis. Prim Care Diabetes 2019; 13:556-567. [PMID: 31040069 DOI: 10.1016/j.pcd.2019.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 11/26/2018] [Accepted: 04/02/2019] [Indexed: 01/28/2023]
Abstract
AIMS Psychological comorbidity, such as depression and/or diabetes-specific emotional distress (DSD), is highly prevalent in people with type 2 diabetes (T2DM) and associated with poorer treatment outcomes. While treatments for depression are well established, interventions specifically designed for DSD are sparse. The aim of this study was to determine interventions that successfully address DSD and HbA1c in people with T2DM. METHODS Seven databases were searched to identify potentially relevant studies. Eligible studies were selected and appraised independently by two reviewers. Multiple meta-analyses and meta-regression analyses were performed to synthesise the data; the primary analyses determined the effect of interventions on DSD, with secondary analyses assessing the effect on HbA1c. RESULTS Thirty-two studies (n = 5206) provided sufficient DSD data, of which 23 (n = 3818) reported data for HbA1c. Meta-analyses demonstrated that interventions significantly reduced DSD (p = 0.034) and HbA1c (p = 0.006) compared to controls, although subgroup meta-analyses and meta-regression to explore specific intervention characteristics that might mediate this effect yielded non-significant findings. CONCLUSIONS The findings demonstrate that existing interventions successfully reduce DSD and HbA1c in people with T2DM. While promising, deductions should be interpreted tentatively, highlighting a stark need for further focused exploration of how best to treat psychological comorbidity in people with T2DM.
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Moran J, Clark CCT, Ramirez-Campillo R, Davies MJ, Drury B. A Meta-Analysis of Plyometric Training in Female Youth: Its Efficacy and Shortcomings in the Literature. J Strength Cond Res 2019; 33:1996-2008. [PMID: 30052601 DOI: 10.1519/jsc.0000000000002768] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Moran, J, Clark, CCT, Ramirez-Campillo, R, Davies, MJ, and Drury, B. A meta-analysis of plyometric training in female youth: its efficacy and shortcomings in the literature. J Strength Cond Res 33(7): 1996-2008, 2019-This meta-analysis characterized female youths' adaptability to plyometric training (PT). A second objective was to highlight the limitations of the body of literature with a view to informing future research. Fourteen studies were included in the final analysis. The effect size (ES = Hedges' g) for the main effect of vertical jump performance was "small" (ES = 0.57, 95% confidence interval: 0.21-0.93). Effect sizes were larger in younger (<15 years; ES = 0.78 [0.25-1.30] vs. 0.31 [-0.18 to 0.80]), shorter (<163 cm; ES = 1.03 [0.38-1.68] vs. 0.25 [-0.20 to 0.70]), and lighter (<54 kg; ES = 1.14 [0.39-1.89] vs. 0.26 [-0.15 to 0.67]) participants. Programming variables seemed to influence adaptive responses with larger effects in interventions which were longer (8 weeks; ES = 1.04 [0.35-1.72] vs. 0.24 [-0.11 to 0.59]), had greater weekly training frequency (>2; ES = 1.22 [0.18-2.25] vs. 0.37 [0.02-0.71]), and whose sessions were of longer duration (≥30 minutes ES = 1.16 [0.14-2.17] vs. 0.33 [0.03-0.63]). More than 16 sessions per program (0.85 [0.18-1.51]) was more effective than exactly 16 sessions (0.46 [0.08-0.84]) which, in turn, was more effective than less than 16 (0.37 [-0.44 to 1.17]). These findings can inform the prescription of PT in female youth.
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Fuentes-Lemus E, Mariotti M, Hägglund P, Leinisch F, Fierro A, Silva E, López-Alarcón C, Davies MJ. Binding of rose bengal to lysozyme modulates photooxidation and cross-linking reactions involving tyrosine and tryptophan. Free Radic Biol Med 2019; 143:375-386. [PMID: 31446058 DOI: 10.1016/j.freeradbiomed.2019.08.023] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 08/07/2019] [Accepted: 08/21/2019] [Indexed: 01/15/2023]
Abstract
This work examined the hypothesis that interactions of Rose Bengal (RB2-) with lysozyme (Lyso) might mediate type 1 photoreactions resulting in protein cross-linking even under conditions favoring 1O2 formation. UV-visible spectrophotometry, isothermal titration calorimetry (ITC), and docking analysis were employed to characterize RB2--Lyso interactions, while oxidation of Lyso was studied by SDS-PAGE gels, extent of amino acid consumption, and liquid chromatography (LC) with mass detection (employing tryptic peptides digested in H218O and H2O). Docking studies showed five interaction sites including the active site. Hydrophobic interactions induced a red shift of the visible spectrum of RB2- giving a Kd of 4.8 μM, while data from ITC studies, yielded a Kd of 0.68 μM as an average of the interactions with stoichiometry of 3.3 RB2- per Lyso. LC analysis showed a high consumption of readily-oxidized amino acids (His, Trp, Met and Tyr) located at different and diverse locations within the protein. This appears to reflect extensive damage on the protein probably mediated by a type 2 (1O2) mechanism. In contrast, docking and mass spectrometry analysis provided evidence for the generation of specific intra- (Tyr23-Tyr20) and inter-molecular (Tyr23-Trp62) Lyso cross-links, and Lyso dimer formation via radical-radical, type 1 mechanisms.
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Shu N, Cheng Q, Arnér ESJ, Davies MJ. Inhibition and crosslinking of the selenoprotein thioredoxin reductase-1 by p-benzoquinone. Redox Biol 2019; 28:101335. [PMID: 31590044 PMCID: PMC6812298 DOI: 10.1016/j.redox.2019.101335] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 09/23/2019] [Accepted: 09/26/2019] [Indexed: 11/03/2022] Open
Abstract
Quinones are common in nature, and often cytotoxic. Their proposed toxicity mechanisms involve redox cycling with radical generation, and/or reactions with nucleophiles, such as protein cysteine (Cys) residues, forming adducts via Michael addition reactions. The selenenyl anion of selenocysteine (Sec) is a stronger nucleophile, more prevalent at physiological pH, and more reactive than the corresponding thiolate anion of Cys. We therefore hypothesized that Sec residues should be readily modified by quinones and with potential consequences for the structure and function of selenoproteins. Here, we report data on the interaction of p-benzoquinone (BQ) with the selenoprotein thioredoxin reductase-1 (TrxR1), which exposes an accessible Sec residue upon physiological reduction by NADPH. Our results reveal that BQ targets NADPH-reduced TrxR1 and inhibits its activity using 5,5′-dithiobis(2-nitrobenzoic acid) or juglone as model substrates, consistent with the targeting of both the Cys and Sec residues of TrxR1. In the absence of NADPH, BQ modified the non-catalytic Cys residues, leading to subunit crosslinking, mainly through disulfides, which also resulted in some loss of activity. This crosslinking was time-dependent and independent of the Sec residue. Addition of NADPH after BQ pre-treatment could resolve the disulfide-linked crosslinking. TrxR activity loss was also observed upon incubation of J774A.1 cells or cell lysates with BQ. These data suggest that BQ readily targets TrxR1, albeit in a rather complex manner, which results in structural changes and loss of enzyme activity. We suggest that TrxR1 targeting can explain some of the cytotoxicity of BQ, and potentially also that of other quinone compounds.
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Giblin L, Yalçın AS, Biçim G, Krämer AC, Chen Z, Callanan MJ, Arranz E, Davies MJ. Whey proteins: targets of oxidation, or mediators of redox protection. Free Radic Res 2019; 53:1136-1152. [PMID: 31510814 DOI: 10.1080/10715762.2019.1632445] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Bovine whey proteins are highly valued dairy ingredients. This is primarily due to their amino acid content, digestibility, bioactivities and their processing characteristics. One of the reported bioactivities of whey proteins is antioxidant activity. Numerous dietary intervention trials with humans and animals indicate that consumption of whey products can modulate redox biomarkers to reduce oxidative stress. This bioactivity has in part been assigned to whey peptides using a range of biochemical or cellular assays in vitro. Superimposing whey peptide sequences from gastrointestinal samples, with whey peptides proven to be antioxidant in vitro, allows us to propose peptides from whey likely to exhibit antioxidant activity in the diet. However, whey proteins themselves are targets of oxidation during processing particularly when exposed to high thermal loads and/or extensive processing (e.g. infant formula manufacture). Oxidative damage of whey proteins can be selective with regard to the residues that are modified and are associated with the degree of protein unfolding, with α-Lactalbumin more susceptible than β-Lactoglobulin. Such oxidative damage may have adverse effects on human health. This review summarises how whey proteins can modulate cellular redox pathways and conversely how whey proteins can be oxidised during processing. Given the extensive processing steps that whey proteins are often subjected to, we conclude that oxidation during processing is likely to compromise the positive health attributes associated with whey proteins.
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Ávila F, Ravello N, Zanocco AL, Gamon LF, Davies MJ, Silva E. 3-Hydroxykynurenine bound to eye lens proteins induces oxidative modifications in crystalline proteins through a type I photosensitizing mechanism. Free Radic Biol Med 2019; 141:103-114. [PMID: 31128239 DOI: 10.1016/j.freeradbiomed.2019.05.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/19/2019] [Accepted: 05/21/2019] [Indexed: 12/27/2022]
Abstract
Photosensitized reactions mediated by endogenous chromophores have been associated with the etiology of age-related cataract disease. Endogenous chromophores such as 3-hydroxykynurenine (3OHKN) can be found in both free form, and bound to crystallin proteins. However, their efficiency in generating photo-induced oxidative modifications on eye lens proteins is not completely understood. In this work, the efficiency and photodynamic activity of 3OHKN bound to both lysine (3OHKN-Lys) and bovine lens proteins (3OHKN-BLP) was assessed and compared with the photosensitizing activity of the major chromophore arising from glucose degradation (GDC). The photosensitizing activity of 3OHKN-Lys, 3OHKN-BLP and GDC was characterized by measurement of singlet oxygen quantum yields, O2 consumption, SDS-PAGE and amino acid analysis of the photo-oxidized proteins. Singlet oxygen quantum yields under 20% O2 atmosphere were 0.02, 0.01, and 0.27 for 3OHKN-Lys, 3OHKN-BLP and GDC, respectively. O2 consumption by photosensitized reactions was more efficient for 3OHKN-BLP, with the extent of O2 consumption being ∼28% higher than for 3OHKN-Lys and GDC under both 5 and 20% O2. SDS-PAGE showed that protein crosslinking is dependent on the O2 concentration, and more extensive at 5 than 20% O2. GDC and 3OHKN-Lys were the most efficient crosslinkers at 20 and 5% O2, respectively. Amino acid analysis of the irradiated proteins showed consumption of Trp, His, Tyr and Phe, and formation of kynurenine (from Trp), methionine sulfoxide (from Met) and DOPA (from Tyr). Kynurenine formation was dependent on the O2 concentration with higher amounts detected at 5 than 20% O2 for 3OHKN-BLP and 3OHKN-Lys, with 3OHKN-BLP the most efficient sensitizer. Our results suggest that 3OHKN-BLP can elicit photo-oxidative damage mainly by a type I photosensitizing mechanism, with this likely to be the most prevalent pathway at the low physiologic O2 concentrations in the eye lens.
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Razieh C, Khunti K, Davies MJ, Edwardson CL, Henson J, Darko N, Comber A, Jones A, Yates T. Association of depression and anxiety with clinical, sociodemographic, lifestyle and environmental factors in South Asian and white European individuals at high risk of diabetes. Diabet Med 2019; 36:1158-1167. [PMID: 31081286 DOI: 10.1111/dme.13986] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/10/2019] [Indexed: 11/27/2022]
Abstract
AIM To investigate the prevalence and correlates of depressive and anxiety symptoms within South Asian and white European populations at high risk of developing Type 2 diabetes. METHODS Data were collected at baseline, and at 12, 24 and 36 months from 1429 white European individuals (age 64±7 years, 35.8% women) and 160 South Asian individuals (age 59±9 years, 30.6% women) who were at high risk of Type 2 diabetes and who took part in two Type 2 diabetes prevention trials in Leicestershire, UK. The Hospital Anxiety and Depression Scale was administered during each study visit. Clinical, sociodemographic, lifestyle and environmental data were collected. RESULTS At baseline, the burden of depressive symptoms varied by ethnic group and gender, with 9.9% of white European men, 14.9% of white European women, 23.6% of South Asian men and 29.2% of South Asian women exceeding the cut-off score for mild-to-severe depression. During the course of the study and after adjustment for clinical, sociodemographic, lifestyle and environmental factors, depressive symptoms remained higher in the South Asian compared to the white European participants [score higher by 1.5, 95% CI 0.9-2.1]. Levels of anxiety were also higher in the South Asian participants, although associations were attenuated after adjustment. Social deprivation, BMI, proximity to fast-food outlets and physical activity were correlates for depression in both the South Asian and white European participants. CONCLUSIONS A higher burden of depressive symptoms was consistently evident among the South Asian individuals, even after adjustment for multiple covariates. It is important to understand both the reasons why these differences are present, to help reduce health inequalities, and whether higher levels of depressive symptoms affect the uptake of and retention rates in diabetes prevention programmes in South Asian communities.
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Gentile C, Kesteven S, Wu J, Bursill C, Davies MJ, Figtree G. Abstract 138: A Novel Cellular and Genetic Approach to Investigate the Cardioprotective Role Played by Endothelial Nitric Oxide Synthase in Myocardial Infarction. Circ Res 2019. [DOI: 10.1161/res.125.suppl_1.138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The loss of regenerative properties in adult cardiomyocytes (CMs) is directly linked to their inability to proliferate. Following an extensive ischaemic event in an aged heart, fibrotic scar formation is the only repair process and eventually heart failure develops. However, molecular and cellular cues in the neonatal heart support that cardiac regeneration is possible in presence of proliferating CMs. Based on previous studies demonstrating that endothelial nitric oxide synthase (eNOS) regulates proliferation in both endothelial cells (ECs) and CMs, we hypothesized that eNOS signaling could play a cardioprotective role. To test our hypothesis, we injected different combinations of co-cultured ECs and CMs in the LV muscle wall of MI mice (permanent LAD ligation). First, injected cells were isolated from either WT or KO eNOS neonatal mice and then co-cultured to form 3D vascularized cardiac spheroids (VCSs), which were eventually transplanted in adult MI mice on the day of the procedure. Control infarcted animals received media-only (vehicle). Other mice received a suspension of co-cultured VCSs in media as follows:
i
) WT CMs and ECs;
ii
) WT CMs and KO ECs;
iii
) KO CMs and WT ECs. Following 28 days, injection of WT cells increased the ejection fraction (EF%) by 20% compared with control animals (61%±4% and 41%±11%, respectively). When eNOS was absent in either CMs or ECs, the EF% was 40%±5% and 46%±2%, respectively, suggesting that the eNOS-mediated protection is dependent on its presence in both cells. Histological analyses confirmed the presence of WT VCSs in MI mice, contributing to a thicker wall thickness compared to vehicle MI mice. No VCSs were observed in the LV wall when KO cells were injected. Therefore, our results strongly suggest that eNOS may play a major role via both an autocrine (CMs) and paracrine (ECs) mechanism. Current studies are focusing on further evaluating the mechanism(s) for this eNOS-mediated protective role. To our knowledge, this is the first study combining cellular and genetic approaches to evaluate the cardioprotective role of eNOS in the heart. A better understanding of this mechanisms may have significant impact for the development of improved molecular and cell therapeutics (including stem cells) for heart failure patients.
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Tiwari MK, Hägglund PM, Møller IM, Davies MJ, Bjerrum MJ. Copper ion / H 2O 2 oxidation of Cu/Zn-Superoxide dismutase: Implications for enzymatic activity and antioxidant action. Redox Biol 2019; 26:101262. [PMID: 31284117 PMCID: PMC6614508 DOI: 10.1016/j.redox.2019.101262] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 06/18/2019] [Accepted: 06/26/2019] [Indexed: 01/25/2023] Open
Abstract
Copper ion-catalyzed oxidation of yeast SOD1 (ySOD1) was examined to determine early oxidative modifications, including oxidation of a crucial disulfide bond, and the structural and functional repercussions of these events. The study used distinct oxidative conditions: Cu2+/H2O2, Cu2+/H2O2/AscH− and Cu2+/H2O2/glucose. Capillary electrophoresis experiments and quantification of protein carbonyls indicate that ySOD1 is highly susceptible to oxidative modification and that changes can be detected within 0.1 min of the initiation of the reaction. Oxidation-induced structural perturbations, characterized by circular dichroism, revealed the formation of partially-unfolded ySOD1 species in a dose-dependent manner. Consistent with these structural changes, pyrogallol assay indicates a partial loss of enzymatic activity. ESI-MS analyses showed seven distinct oxidized ySOD1 species under mild oxidation within 0.1 min. LC/MS analysis after proteolytic digestion demonstrated that the copper-coordinating active site histidine residues, His47 and His49, were converted into 2-oxo-histidine. Furthermore, the Cu and Zn bridging residue, His64 is converted into aspartate/asparagine. Importantly, the disulfide-bond Cys58-Cys147 which is critical for the structural and functional integrity of ySOD1 was detected as being oxidized at Cys147. We propose, based on LC/MS analyses, that disulfide-bond oxidation occurs without disulfide bond cleavage. Modifications were also detected at Met85 and five surface-exposed Lys residues. Based on these data we propose that the Cys58-Cys147 bond may act as a sacrificial target for oxidants and protect ySOD1 from oxidative inactivation arising from exposure to Cu2+/H2O2 and auto-inactivation during extended enzymatic turnover. Oxidation of yeast superoxide dismutase (ySOD1) by Cu2+/H2O2 is examined. Rapid modification of His, Met, Cys and Lys residues detected by LC-MS methods. Oxidation of active site His residues and partial protein unfolding are early events. The Cys58-Cys147 disulfide bond is oxidized and may act as a sacrificial target. Excess exogenous Cu2+ decreases protein damage and can reverse loss of activity.
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Nybo T, Davies MJ, Rogowska-Wrzesinska A. Analysis of protein chlorination by mass spectrometry. Redox Biol 2019; 26:101236. [PMID: 31181457 PMCID: PMC6557747 DOI: 10.1016/j.redox.2019.101236] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/28/2019] [Accepted: 05/31/2019] [Indexed: 01/04/2023] Open
Abstract
Chlorination of tyrosine is a commonly known effect/consequence of myeloperoxidase activity at sites of inflammation, and detection of 3-chlorotyrosine has been used as biomarker for inflammatory diseases. However, few studies have addressed site specific chlorination in proteins, and no methods for large scale chloroproteomics studies have yet been published. In this study, we present an optimized mass spectrometry based protocol to identify and quantify chlorinated peptides from single proteins modified by HOCl (100 and 500 μM, within estimated pathophysiological levels), at a high level of sensitivity and accuracy. Particular emphasis was placed on 1) sensitive and precise detection of modification sites, 2) the avoidance of loss or artefactual creation of modifications, 3) accurate quantification of peptide abundance and reduction of missing values problem, 4) monitoring the dynamics of modification in samples exposed to different oxidant concentrations and 5) development of guidelines for verification of chlorination sites assignment. A combination of an optimised sample preparation protocol, and improved data analysis approaches have allowed identification of 33 and 15 chlorination sites in laminin and fibronectin, respectively, reported in previous manuscripts [1,2]. The method was subsequently tested on murine basement membrane extract, which contains high levels of laminin in a complex mixture. Here, 10 of the major chlorination sites in laminin were recapitulated, highlighting the utility of the method in detecting damage in complex samples. An optimized mass spectrometry method is presented to detect protein chlorination. Reduction and alkylation leads to loss of chlorinated residues. Identification of modification sites in fibronectin and laminin induced by HOCl. Quantification of relative site occupancy (RSO) of chlorinated residues. Largest chloroproteomics dataset to date.
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