Protein Oxidation

The effects of a hydroxyl radical-generating system induced by iron catalyzed oxidation (Fe 2+ /H 2 O 2 ) on lipids and proteins of sardine, Atlantic bonito, anchovy and bluefish were investigated. Thiobarbituric acid-reactive substances (TBARs, mg malonaldehyde/kg fish muscle) formation was used to evaluate oxidative damage of the lipid in dark muscle fish due to iron catalyzed oxidation. The amount of TBARs was observed to increase significantly in sardine and anchovy as the incubation time increased, while Atlantic bonito and bluefish reached their maximum values of TBARs within the first 3 h of incubation, and after that did not change (p < 0.05). Carbonyl contents (nmol carbonyl/mg protein) of all fish samples measured as an index of protein oxidation were affected differently by the iron-catalyzed oxidation system during incubation. However, significant increases in the carbonyl groups were detected in sardine, Atlantic bonito and bluefish, but not in anchovy as a result of the long incubation time (5 h) (p < 0.05). When comparing to increases Atlantic bonito showed the maximum increase protein carbonyl. The electrophoretic patterns in the presence and absence of b-mercaptoethanol showed that a loss of proteins generally occurred in all fish at the end of incubation, and the greatest alteration in protein bands was observed in anchovy during Fe 2+ -catalyzed oxidation. The bands above 50 kDa disappeared within the first 1 h of incubation. The loss of protein (both high and low molecular weight) may involve disulfide and non-disulfide covalent linking during the iron catalyzed incubation. These data suggest that an increase in TBARs and fragmentation, and a loss of proteins exposed to iron-catalyzed oxidation may explain the oxidative damage of lipids and proteins which causes quality loss and limits the storage life of dark muscle fish.

This study presents a method of brush border membrane (BBM) preparation from the human small intestine using polyethylene glycol (PEG) precipitation and also looks at the effect of in vitro oxidant exposure on structural and functional alterations in the membrane. Isolated BBM were relatively pure as judged by 10- to 14-fold enrichment of marker enzymes with less than 1% contamination

Brachiaria grasses face, due principally to climate change, to extreme conditions like drought and waterlogging, which severely limit their productivity and adoption. Therefore is of particular interest its study with aim to develop future breeding programs. Phenotypic differences have been reported in their tolerance to waterlogging. However, there are a few published information regarding the biochemical responses to waterlogging. In this study was evaluated the antioxidant activity of two contrasting genotypes (B. humidicola -679tolerant and B. hybrid Mulato II -36087sensitive) under waterlogged soil conditions. The assays realized were defined in basis of two factor: Antioxidant system (enzymatic-Catalaseand non-enzymatic-DPPH assay-) and Oxidative damage (protein content-Bradford assayand lipid peroxidation-TBARS assay-). We conclude that the outstanding adaptation of B. humidicola to waterlogged soils to long-term (15 days) is related to their non-enzymatic antioxidant system ...

Ageing in the marine pelagic copepod Acartia tonsa results in decreased feeding and production rates associated with an increase in the accumulation of protein oxidative damage, as predicted by the oxidative stress hypothesis. In laboratory experiments, we estimated sex-specific ageing effects on feeding and oxidative damage and on egg production rates of adult females. We also determined maternal effects on offspring by measuring egg hatching success and oxidative damage of nauplii from mothers of different ages. Males manifested more oxidative damage with age than females, providing an alternative explanation for the shorter life span in males. Older females produced fewer offspring, and nauplii with higher protein oxidative damage, than younger females. This study forms an empirical basis to link ageing, life span, sex differences and maternal fitness in animals that also reflects natural copepod population dynamics. Individual ageing processes and the resulting age structure in the population modulate mortality risk, parental effects on offspring performance, reproductive investment, and pelagic energy fluxes.

Alzheimer´s disease (AD) is a complex neurodegenerative disease characterized by progressive destruction of mainly brain cortical areas related to cognitive and memory performances. Most identified forms of AD are idiopathic and the precise pathogenic mechanisms remain yet unknown. Neuropathological hallmarks of AD include amyloid plaques and neurofibrillary tangles whose development correlate with neuronal death. At present, there is evidence that factors other than aging and genetic prone to develop AD contribute as cofactors in neuropathological cascades. Aluminum is considered a neurotoxic metal for humans. Some previous studies have revealed the accumulation of aluminum in the cerebral parenchyma of postmortem brains of patients suffering AD. In this study, we show that aluminum is present in significant amounts in the cerebrospinal fluid (CSF) of control healthy individuals and that its concentration increases in individuals with AD. Aluminum in CSF is also elevated in patients with mild cognitive impairment (MCI), considered to be a prodromal stage of AD. Aluminum contents correlate with classical biomarkers of AD (particularly with phosphorylated tau and amyloid β) following complex association patterns which vary depending on the stage of the AD spectrum, and dismiss a direct relationship. Associated with increased aluminum in AD patients, indicators of oxidative stress, namely Iso-PG2 and MDA, are also increased in the CSF of AD and MCI individuals, which also correlate with aluminum concentration. We hypothesize that aluminum content in CSF is a significant factor which, in synergy with other variables, may favors the initiation and progression of AD.

Gold(I) and gold(III) complexes have been previously investigated for potential biomedical applications including as anti-HIV agents. The oxidising nature of some gold(III) complexes yields well-documented cellular toxicity in cell-based assays but the effect in direct biochemical assays has not been fully investigated. In this study, gold(III) complexes were evaluated in HIV-1 reverse transcriptase and HIV-1 integrase biochemical assays. The gold(III) tetrachlorides KAuCl 4 and HAuCl 4 yielded sub-micromolar IC 50 's of 0.947 and 0.983 lM in the direct HIV-1 RT assay, respectively, while IC 50 's ranging from 0.461 to 8.796 lM were obtained for seven selected gold(III) complexes. The gold(III) tetrachlorides were also effective inhibitors of integrase enzymatic activity with >80% inhibition obtained at a single dose evaluation of 10 lM. RT inhibition was decreased in the presence of a reducing agent (10 mM DTT) and against the M184V HIV-1 RT mutant, while none of the gold(III) complexes were effective inhibitors in cell-based antiviral assays (SI values <5.95). Taken together, the findings of this study demonstrate that gold(III) complexes modify HIV-1 enzyme activity in direct biochemical assays, most likely through protein oxidation.

The objective of this study was to determine the effect of tannic acid (TA) on the oxidative stability and the quality characteristics of ground chicken breast meat. Five treatments including (1) control (none added), (2) 2.5 ppm TA, (3) 5 ppm TA, (4) 10 ppm TA, and (5) 5 ppm butylated hydroxyanisole (BHA) were added to boneless, skinless ground chicken breast meat, and used for both raw and cooked meat studies. For the raw meat study, the ground chicken breast meat was packaged in oxygen-permeable bags and stored at 4 °C for 7 days. For the cooked study, raw ground meat samples were vacuum-packaged in oxygen-impermeable vacuum bags, cooked in-bag to the internal temperature of 75 °C, re-packaged in oxygen-permeable bags, and then stored. Both raw and cooked meats were analyzed for lipid and protein oxidation, color, and volatiles (cooked meat only) at 0, 3, and 7 days of storage. Raw meats with 10 ppm of TA added had significantly (p ≤ 0.05) lower lipid and protein oxidation than o...

Lipid or protein are sensitive to peroxidation and inert gas limit or stop adulterations. Unsaturated lipids are peroxided by ground state dioxygen in presence of catalysts (iron, enzymes) or after thermal dissociation of C=C bond, and by excited state dioxygen without any assistance (photo-oxidation). Inerting fragile oils by bubbling with dinitrogen or carbon dioxide that are soluble gas in oil slows oxidation process during storage or frying. In a same way, limit the oxidation of the tryptophan residues of protein is possible by reducing oxygen content. Oxidation leads also to oxidation of thiol in disulfide, which induced protein cross-linked and decay of functional properties, but also to change of aroma in case of volatile thiols. Bubbling with N2 is preferable in aqueous solution because of buffering effect of CO2. Dioxygen enters in the phenol polymerization of fresh-cut fruits and vegetable but dioxygen cannot be completely eliminated in order to preserve the life of cells.

Gastrodin elata blume (Tianma in Chinese, Chunma in Korean) is a perennial parasitic herbaceous plant native to Korea, Japan and China (Chae et al., 2008). The plant has recently received very good attention, especially in Korea, due to its excellent health-promoting properties. This plant is reported to have excellent antioxidant, anticancer and anti-inflammatory properties. This paper briefly reviews some characteristics and functional properties of Chunma.

J. Neurochem. (2008) 104, 1478–1493.Possible roles of oxidative stress and protein oxidation on alcohol‐induced augmentation of cerebral neuropathy in gp120 administered alcohol preferring rats drinking either pure water (W rats) or a free‐choice ethanol and water (E rats) for 90 days. This study showed that peripherally administered gp120 accumulated into the brain, liver, and RBCs samples from water drinking – gp120 administered rats (Wg rats) and ethanol drinking – gp120 administered rats (Eg rats), although gp120 levels in samples from Eg rats were significantly greater than the levels in samples from Wg rats. The brain samples from ethanol drinking‐saline administered (EC) and Wg rats exhibited comparable levels of free radicals that were significantly lower than the levels in Eg rats. Peroxiredoxin‐I (PrxI) activity in the brain samples exhibited the following pattern: Wg ≫ ≫ WC ≫ EC &gt; Eg. Total protein‐carbonyl and carbonylated hippocampal cholinergic neurostimulating pept...

This study examines the putativegastroprotective effect of adenosine onindomethacininduced gastric lesions and the possiblemechanisms involved. After 24 hr of starvation, the ratswere treated either with indomethacin (Indo; 25 mg/kg,subcutaneously) alone or adenosine + Indo (Ado; 7.5mg/kg, subcutaneously, three times a day), or thevehicle (5% NaHCO3, subcutaneously). Thelength of hemorrhagic lesions in the stomachs was expressed as the lesionindex. The tissue-associated

The effect of chronic exposure to Escherichia coli on morphometrical parameters, different antioxidant defenses, lipid peroxidation and protein oxidation has been studied in digestive gland of the freshwater mussel Diplodon chilensis in the laboratory during 6 weeks. In, a parallel field study, we evaluated morphometrical and oxidative stress parameters in digestive glands of mussels collected from a sewage polluted area (SMA) and from a pristine area (control). Both sites were characterized by analyzing bacteriological and physic-chemical parameters. In the laboratory D. chilensis was able to filter bacteria at high concentrations with a clearing rate of 0.510 ± 0.036 L/h per gram of dry soft tissue mass. The digestive gland mass to shell length ratio (DGM/SL), reduced glutathione (GSH), lipid peroxidation, as concentration of thiobartituric acid reactive substances (TBARS), and glutathione-S-transferase (GST) activity of mussels fed with bacteria were significantly higher than those of control mussels after the fourth week. Fecal bacteria in lake water samples were undetectable in the control, and higher than 24,000 MPN (most probable number)/100 mL in SMA. DGM/SL was higher in SMA. No differences between sites were observed in total lipid and protein content, neither in superoxide dismutase activity. GSH content was higher in SMA, with no difference in the oxidized form. GST activity and MDA were significantly higher in SMA but protein oxidation was not affected.

Because of the large diversity in processed meat products and the potential involvement of oxidation processes in the association between red and processed meat consumption and chronic diseases, the concentration of oxidation products after gastrointestinal digestion of commercial luncheon meat products was investigated. A broad spectrum of meat products (n = 24), displaying large variation in macro-and micronutrient composition and processing procedures, was digested in vitro by simulating digestion fluids of the human gastrointestinal tract. Lipid and protein oxidation was assessed in the meat products before digestion and in the corresponding digests by measurement of free malondialdehyde, 4-hydroxy-2-nonenal, hexanal and protein carbonyl compounds. Compared to an unprocessed cooked pork mince, that was included as a reference in the digestion experiment, levels of lipid oxidation products were low in the digests of most meat products. Only the digests of Parma ham had slightly higher or comparable levels as the reference pork. In contrast, protein carbonyl compounds were comparable or up to 6 times higher in the processed meat products compared to the reference pork. Particularly raw-cooked and precooked-cooked meat products and corresponding digests had higher protein carbonyl levels, but also lower protein contents and higher fat to protein ratios. In conclusion, most luncheon meat products and corresponding digests contained lower amounts of free lipid oxidation products, but more protein carbonyl compounds compared to the reference pork.

Introduction: Hyperlipidaemia is a major risk factor for cardiovascular diseases and may be associated with metabolic syndrome. Olive oil contains monounsaturated fatty acids (MUFA) and various phytochemicals which have beneficial role in hyperlipidaemia.

Objective - The present study was conducted to explore the antihyperlipidaemic effect of olive oil.

Methods -We studied 60 hyperlipidaemic male subjects between 40 to 55 yrs of age who were divided into study (n=30) and control groups (n=30). The duration of this study was 6 weeks during which both the groups were allowed to take routine diet and study group was given additional 30 ml of olive oil per day.

Result - After 6 weeks, study group showed a significant fall in triglycerides, LDL and total cholesterol while a significant rise in HDL was recorded.

Conclusion- Thus, use of olive oil improved the serum lipid profile.

Yeast cells lacking the mitochondrial NADH kinase encoded by POS5 display increased sensitivity to hydrogen peroxide, a slow-growth phenotype, reduced mitochondrial function and increased levels of mitochondrial protein oxidation and mtDNA mutations. Here we examined gene expression in pos5 cells, comparing these data to those from cells containing deletions of superoxide dismutaseencoding genes SOD1 or SOD2. Surprisingly, stress response genes were down-regulated in pos5, sod1 and sod2 cells, implying that cells infer stress levels from mitochondrial activity rather than sensing reactive oxygen species directly. Additionally, pos5, but not sod1 or sod2, cells displayed an anaerobic expression profile, indicating a defect in oxygen sensing that is specific to pos5, and is not a general stress response. Finally, the pos5 expression profile is quite similar to the hap1 expression profile previously reported, which may indicate a shared mechanism.

Yeast cells lacking the mitochondrial NADH kinase encoded by POS5 display increased sensitivity to hydrogen peroxide, a slow-growth phenotype, reduced mitochondrial function and increased levels of mitochondrial protein oxidation and mtDNA mutations. Here we examined gene expression in pos5 cells, comparing these data to those from cells containing deletions of superoxide dismutaseencoding genes SOD1 or SOD2. Surprisingly, stress response genes were down-regulated in pos5, sod1 and sod2 cells, implying that cells infer stress levels from mitochondrial activity rather than sensing reactive oxygen species directly. Additionally, pos5, but not sod1 or sod2, cells displayed an anaerobic expression profile, indicating a defect in oxygen sensing that is specific to pos5, and is not a general stress response. Finally, the pos5 expression profile is quite similar to the hap1 expression profile previously reported, which may indicate a shared mechanism.

Interferon-γ (IFN-γ) is a key cytokine in the adaptive immune response that is primarily secreted from CD4+ T helper cells to induce Cytotoxic T lymphocyte (CTL) cell response against HCV infection. IFN-γ activates macrophages in the liver resulting in inhibition of viral replication and increased NO production. HCV-infected macrophages are major producers of NO in the liver. It is not completely understood how HCV proteins affect iNOS expression and what the role of IFN-γ is in HCV protein expression in HCV-infected macrophages. Objective: Evaluate hepatitis C virus proteins' regulation of IFN-γ-activated macrophage cell line. Methods: RAW-264.7 cells were seeded in 6 well-plates and transfected with HCV protein expressing plasmids using lipofectamine. After treating with IFN-γ, we determined the iNOS and HCV core, NS5A and E1 protein expression with immunoblotting. Results: Consistent with other studies, HCV core and NS5A proteins induced iNOS expression in macrophages. Moreover, HCV E1 protein-enhanced iNOS expression is highest in the presence and absence of IFN-γ activation. Conclusion: These results indicate that hepatitis C virus core, NS5A, E1 protein regulates iNOS protein expression in IFN-γ-activated and resting macrophage cell lines. These findings point to a future research direction for understanding the pathogenesis of HCV-related liver inflammation.

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are produced, in part, from NADPH oxidase in response to host invasion and tissue injury. Defects in NADPH oxidase impair host defense; however, the role of ROS and RNS in the response to tissue injury is not known. We addressed this issue by subjecting leukocyte oxidase (Nox2)-deficient (Nox2 -/- ) mice to arterial injury. Femoral artery injury was associated with increased Nox2 expression, ROS/RNS production, and oxidative protein and lipid modification in wild-type mice. In Nox2 -/- mice, RNS-mediated protein oxidation, as monitored by protein nitrotyrosine content, was significantly diminished. This was accompanied by reduced neointimal proliferation, as monitored by intimal thickness and intimal/medial ratio, in Nox2 -/- compared to wild-type mice. In addition, Nox2 deficiency led to reduced cellular proliferation and leukocyte accumulation. These data indicate that Nox2-mediated oxidant production has a requisit...

Mitochondrial NO production was assayed in rats submitted to hypobaric hypoxia and in normoxic controls (53.8 and 101.3 kPa air pressure, respectively). Heart mitochondria from young normoxic animals produced 0.62 and 0.37 nmol NO/min.mg protein in metabolic states 4 and 3, respectively. This production accounts for a release to the cytosol of 29 nmol NO/min.g heart and for 55 % of the NO generation. The mitochondrial nitric oxide synthase (mtNOS) activity measured in submitochondrial membranes at pH 7.4 was 0.69 nmol NO/min. mg protein. Rats exposed to hypobaric hypoxia for 2 to 18 mo showed 20-60 % increased left ventricle mtNOS activity as compared with their normoxic siblings. Left ventricle NADH-cytochrome oxidase and cytochrome oxidase activities decreased by 36 % and 12 % from 2 to 18 mo of age, but were not affected by hypoxia. Mitochondrial NOS up-regulation in hypoxia was associated with a retardation of the decline in the mechanical activity of papillary muscle upon aging...

The aim of this work was to study the influence of different pastures (Intensive ryegrass, Botanically diverse and Leguminosa rich pastures) on the antioxidant status and oxidative stability of meat from lambs that had been exclusively grazing for three months. Lipid, colour and protein oxidation, a-tocopherol content and activity of antioxidant enzymes (superoxide dismutase (SOD), catalase (Cat) and glutathione peroxidase (GSH-Px)) were measured in Longisimus thoracis et lumborum muscle samples taken 1 day after slaughter. Pasture type significantly affected protein oxidation and the activity of GSH-Px, but no significant differences were found for the a-tocopherol content, colour and lipid oxidation, and the activities of SOD and Cat. Grazing a Botanically diverse pasture induced significantly higher protein oxidation in meat, as measured by the free thiol and carbonyl contents, compared to a Leguminosa rich or Intensive ryegrass pasture (P < 0.05). The GSH-Px activity was significantly higher in meat from lambs on the Leguminosa rich pasture compared to the other pasture groups (P < 0.01).

Objective: To assess if oxidative injury in intrauterine growth retarded and healthy newborns is affected by the mode of delivery and whether Apgar score as a marker of neonatal survival is dependent on lipid and protein oxidative injury assessed by measuring malondialdehyde and protein carbonylation. Methods: 30 IUGR newborns, 15 born by normal vaginal delivery and 15 born by elective caesarean section, and 40 healthy control infants, 30 born by normal vaginal delivery and 10 born by elective caesarean section, were studied at birth. Cord blood was collected for determination of malondialdehyde and protein carbonylation. Results: IUGR newborns had significantly elevated MDA and protein carbonylation than the control group. Apgar scores, both at 1 and 5 min, were significantly lower in the IUGR group. These were assessed by independent sample t test. Using one-way ANOVA we found that MDA and protein carbonyls levels were not statistically different in healthy control group and in IUGR subgroup born by caesarean section however they were significantly different in other groups. Linear regression analysis revealed that Apgar scores both at 1 min and 5 min were dependent on MDA in IUGR newborns. Apgar score was however not dependent on protein carbonylation in the same group. Conclusion: Apgar score in IUGR newborns is dependent on the extent of oxidative injury and elective caesarean section minimises the same.

Aging is characterized by a gradual functional decrease of all systems including the kidneys. Growing evidence links altered lipid protein redox-homeostasis with renal dysfunction. The effect of sexual dimorphism on the lipid protein redox-homeostasis mechanisms in the aging kidney is obscure. In the current study, we aimed to investigate redox homeostasis as it related to sexual dimorphism on protein oxidation and lipid peroxidation parameters, as protein carbonyl (PCO), total thiol (T-SH), advanced oxidation protein products (AOPP), malondialdehyde, glutathione (GSH), and superoxide dismutase (SOD) activity, as potential aging biomarkers, which may contribute to an analysis of the free radical theory of aging. Materials and methods: The study was carried out with 16 naturally aged rats (24 months old; eight males and eight females) and their corresponding young rat groups as controls (6 months old; eight males and eight females). All of the aforementioned parameters (PCO, T-SH, AOPP, MDA, GSH, SOD) were measured manually instead of automated devices or ELISA kits. Results: PCO, AOPP, and malondialdehyde levels in aged rats were significantly higher in the older rat group than in the younger rat group, whereas SOD activities were significantly lower in old rats. T-SH levels were not significantly different in male groups; however, T-SH levels were lower in the aged female group than in the young female control group. In addition, GSH levels were significantly different between the aged rat group and the corresponding young control group for both genders. Conclusion: With respect to PCO and AOPP, impaired redox homeostasis is substantially more prominent in males than females. The decrease of G-SH levels in male groups could be attributed to stabilizing the redox status of protein thiol groups by the depletion of the GSH groups. Considering the results, the renal tissue proteins and lipids in different genders may have different susceptibilities to oxidative damage.

Free radical-mediated oxidation of proteins results in the formation of carbonyl groups in quantities that reflect the intensity of the oxidative stress. We have developed an immunochemical technique for the quantification of carbonyl groups in protein samples prepared from small tissue samples and cell cultures. Protein samples were slot-blotted onto a polyvinylidene difluoride membrane, which was sequentially treated with 2,4-dinitrophenylhydrazine (DNPH), a primary antibody specific for the 2,4-dinitrophenol group, and a peroxidase-labeled second antibody. After the blots were developed with a chemiluminescent substrate and exposed to X-ray film, the level of immunostaining was quantitated by densitometry. Using oxidized bovine serum albumin as a standard and loading 5 g of protein per slot, the minimum detectable carbonyl content was approximately 60 pmol carbonyl/mg protein. When necessary, nonspecific staining by noncarbonyl constituents in complex sample matrices was accounted for by using sodium borohydride-treated blanks. Results by the new method were highly correlated (r ‫؍‬ 0.932, P < 0.0001) with those of the standard DNPH-based spectrophotometric technique. The coefficient of variation at a carbonyl level of 1.5 nmol/mg protein was 9.7%. The utility of this new method was demonstrated by measuring protein oxidation in cultured human colon cells (SW620) that were briefly exposed to H 2 O 2 .

Elimination of celiac-toxic prolamin peptides and proteins is essential for Triticeae products to be gluten-free. Instead of enzymatic hydrolysis, in this study we investigated metal-catalyzed oxidation of two model peptides, QQPFP, and PQPQLPY, together with a hordein isolate from barley (Hordeum vulgare L.). We established a multiple reaction monitoring (MRM) LC-MS method to detect and quantify proline oxidation fragments. In addition to fragmentation, aggregation and side chain modifications were identified, including free thiol loss, carbonyl formation, and dityrosine formation. The immunoreactivity of the oxidized hordein isolate was considerably decreased in all metal-catalyzed oxidation systems. Cleavage of peptides or protein fragments at the numerous proline residues partially accounts for the decrease. Metal-catalyzed oxidation can thus be used in the modification and elimination of celiac-toxic peptides and proteins.

Repression of activation of c‐Jun N‐terminal kinase (JNK) participates in the anti‐apoptotic effect of nuclear factor‐κB (NF‐κB) in TNFα‐treated Ewing sarcoma cells. As oxidative stress is one of the most prominent activators of JNK, we investigated the relationship between TNFα‐induced NF‐κB activation and the control of oxidative stress. Inhibition of NF‐κB activation resulted in an increase in TNFα‐induced ROS production, lipid peroxidation and protein oxidation. Those ROS and lipid peroxides were both involved in TNFα‐induced apoptosis, whereas only ROS elevation triggered sustained JNK activation. TNFα increased the level of two antioxidant enzymes, thioredoxin and manganese superoxide dismutase by an NF‐κB‐dependent mechanism. Inhibition of expression or activity of these enzymes sensitized cells to TNFα‐induced apoptosis, indicating their functional role in protection from cell death. Thus, agents that inhibit activities of these enzymes may prove helpful in the treatment of ...

Mediated-acid intramolecular cyclisation of 4-N-p-methylphenylamino-4-pyridyl-l-butenes 4-6 was used to obtain new C-2 pyridyl substituted 4,6-dimethyl-l,2,3,4-tetrahydroquinoiines 7-9, which were oxidised then to their aromatic analogues 10-12 in good yields.

The Chlamydia trachomatis divalent cation-dependent regulator (DcrA), encoded by open reading frame CT296, is a distant relative of the ferric uptake regulator (Fur) family of iron-responsive regulators. Chlamydial DcrA specifically binds to a consensus Escherichia coli Fur box and is able to complement an E. coli Fur mutant. In this report, the E. coli Fur titration assay (FURTA) was used to locate chlamydial genomic sequences that are recognized by E. coli Fur. The predictive regulatory regions of 28 C. trachomatis open reading frames contained sequences functionally recognized by E. coli Fur; targets include components of the type III secretion pathway, elements involved in envelope and cell wall biogenesis, predicted transport proteins, oxidative defense enzymes, and components of metabolic pathways. Selected FURTA-positive sequences were subsequently examined for recognition by C. trachomatis DcrA using an electrophoretic mobility shift assay. The resultant data show that C. tr...

Reduced glutathione or simply glutathione (g-glutamylcysteinylglycine; GSH) is found in the cytosol of most cells of the body. GSH in the epithelial lining fluid (ELF) of the lower respiratory tract is thought to be the first line of defense against oxidative stress. Inhalation (nebulized or aerosolized) is the only known method that increases GSH&apos;s levels in the ELF. A review of the literature was conducted to examine the clinical effectiveness of inhaled GSH as a treatment for various pulmonary diseases and respiratory-related conditions. This report also discusses clinical and theoretical indications for GSH inhalation, potential concerns with this treatment, its presumed mechanisms of action, optimal doses to be administered and other important details. Reasons for inhaled GSH&apos;s effectiveness include its role as a potent antioxidant, and possibly improved oxygenation and host defenses. Theoretical uses of this treatment include Farmer&apos;s lung, pre-and postexercise,...

Introduction: Plasma oxidized human serum albumin (OxHSA) is evidence of an active antioxidant mechanism as measured by oxidized species of HSA. CXCL-10 is a pro-inflammatory chemokine associated with ischemic conditions. Accordingly, we examined the relationship of admission OxHSA and CXCL-10 with discharge mRS in acute ischemic stroke (AIS). Methods: Plasma samples and clinical data were collected prospectively at a Comprehensive Stroke Center. Admission biomarkers of oxidative stress, CXCL-10 and %OxHSA, were measured. We examined if CXCL-10 or %OxHSA correlated with age, admission NIHSS score, and discharge mRS score using Spearman's Rank correlation. Logistic regression was performed to identify independent predictors of a favorable discharge mRS (≤2). Results: In 106 consecutive AIS patients, the median age was 73 (IQR 61-84), 47% were male, and the median admission NIHSS score was 11 (IQR 5-19). %OxHSA and CXCL-10 were significantly correlated (r = 0.23, p = 0.02). Both biomarkers were significantly correlated with age: %OxHSA (r = 0.44, p < 0.001) and CXCL-10 (r = 0.32, p = 0.001). Neither biomarker was correlated with admission NIHSS. There was a borderline significant correlation with discharge mRS and %OxHSA (r = −0.17, p = 0.08), where higher %OxHSA correlated with lower discharge mRS scores. For every 1% increase in %OxHSA, the odds of a favorable discharge mRS increased 11%. The odds of a favorable discharge mRS decreased 18% for every 1-point increase in the initial NIHSS. Conclusions: OxHSA, the result of an oxidative environment and evidence of the strong antioxidant buffering capacity of HSA, correlated with CXCL-10 and discharge mRS, implying that strong antioxidant activity of albumin may confer better outcomes.

Oxidative stress and the production of intracellular reactive oxygen species (ROS) have been implicated in the pathogenesis of a variety of diseases. In excess, ROS and their byproducts that are capable of causing oxidative damage may be cytotoxic to cells. However, it is now well established that moderate amounts of ROS play a role in signal transduction processes such as cell growth and posttranslational modification of proteins. Oxidants, antioxidants, and other determinants of the intracellular reduction-oxidation (redox) state play an important role in the regulation of gene expression. Recent insights into the etiology and pathogenesis of atherosclerosis suggest that this disease may be viewed as an inflammatory disease linked to an abnormality in oxidation-mediated signals in the vasculature. In this review, we summarize the evidence supporting the notion that oxidative stress and the production of ROS function as physiological regulators of vascular gene expression mediated via specific redox-sensitive signal transduction pathways and transcriptional regulatory networks. Elucidating, at the molecular level, the regulatory processes involved in redox-sensitive vascular gene expression represents a foundation not only for understanding the pathogenesis of atherosclerosis and other inflammatory diseases but also for the development of novel therapeutic treatment strategies.

Oxidatively modified forms of proteins accumulate during aging. Oxidized protein conformers might act as intermediates in the formation of amyloids in age-related disorders. However, it is not known whether this amyloidogenic conversion requires an extensive protein oxidative damage or it can be promoted just by a discrete, localized post-translational modification of certain residues. Here, we demonstrate that the irreversible oxidation of a single free Cys suffices to severely perturb the folding energy landscape of a stable globular protein, compromise its kinetic stability, and lead to the formation of amyloids under physiological conditions. Experiments and simulations converge to indicate that this specific oxidation-promoted protein aggregation requires only local unfolding. Indeed, a large scale analysis indicates that many cellular proteins are at risk of undergoing this kind of deleterious transition; explaining how oxidative stress can impact cell proteostasis and subsequ...

In traditional medicine, Eucalyptus globulus (eucalyptus) was used for the treatment of diabetes mellitus. Hyperglycemia in diabetes has been associated with increased formation of reactive oxygen species (ROS) and oxidative damage to tissue compounds. The aim of this study was to evaluate the effects of eucalyptus in the diet (20 g/Kg) and drinking water (2.5 g/L) on lipid peroxidation, protein oxidation and antioxidant power in plasma and liver homogenate, as well as glycated-Hb (HbA 1C) of blood in streptozotocin-induced diabetic rats for a period of 4 weeks. Diabetes induced in rats by a single intraperitoneal injection of streptozotocin (STZ, 65 mg/Kg). At the end of the treatment period, the level of plasma glucose, plasma and liver malondialdehyde (MDA, the main product of lipid peroxidation), protein carbonyl (PC, one of the protein oxidation products) and HbA 1C increased and ferric reducing antioxidant power (FRAP) decreased in diabetic rats compared to normal rats. Eucalyptus administration for 4 weeks caused a significant decrease in the plasma glucose levels, plasma and liver MDA, PC and HbA 1C , also a concomitant increase in the levels of FRAP in diabetic treated rats. In conclusion, the present study showed that eucalyptus posses antioxidant activities. Eucalyptus probably restores antioxidant power, due to the improved hyperglycemia in streptozotocin-induced diabetic rats.

Oxidation of methionine residues is involved in several biochemical processes and in degradation of therapeutic proteins. The relationship between conformational stability and methionine oxidation in recombinant human interleukin-1 receptor antagonist (rhIL-1ra) was investigated to document how thermodynamics of unfolding affect methionine oxidation in proteins. Conformational stability of rhIL-1ra was monitored by equilibrium urea denaturation, and thermodynamic parameters of unfolding (∆G H2O , m, and C m) were estimated at different temperatures. Methionine oxidation induced by hydrogen peroxide at varying temperatures was monitored during "coincubation" of rhIL-1ra with peptides mimicking specific regions of the reactive methionine residues in the protein. The coincubation study allowed estimation of oxidation rates in protein and peptide at each temperature from which normalized oxidation rate constants and activation energies were calculated. The rate constants for buried Met-11 in the protein were lower than for methionine in the peptide with an associated increase in activation energy. The rate constants and activation energy of solvent exposed methionines in protein and peptide were similar. The results showed that conformational stability, monitored using the C m value, has an effect on oxidation rates of buried methionines. The rate constant of buried Met-11 correlated well with the C m value but not ∆G H2O. No correlation was observed for the oxidation rates of solvent-exposed methionines with any thermodynamic parameters of unfolding. The findings presented have implications in protein engineering, in design of accelerated stability studies for protein formulation development, and in understanding disease conditions involving protein oxidation.

Mild cognitive impairment (MCI) is generally referred to the transitional zone between normal cognitive function and early dementia or clinically probable Alzheimer's disease (AD). Oxidative stress plays a significant role in AD and is increased in the superior/ middle temporal gyri of MCI subjects. Because AD involves hippocampal-resident memory dysfunction, we determined protein oxidation and identified the oxidized proteins in the hippocampi of MCI subjects. We found that protein oxidation is significantly increased in the hippocampi of MCI subjects when compared to age-and sex-matched controls. By using redox proteomics, we determined the oxidatively modified proteins in MCI hippocampus to be A-enolase (ENO1), glutamine synthetase (GLUL), pyruvate kinase M2 (PKM2) and peptidyl-prolyl cis/trans isomerase 1 (PIN1). The interacteome of these proteins revealed that these proteins functionally interact with SRC, hypoxia-inducible factor 1, plasminogen (PLG), MYC, tissue plasminogen activator (PLAT) and BCL2L1. Moreover, the interacteome indicates the functional involvement of energy metabolism, synaptic plasticity and mitogenesis/proliferation. Therefore, oxidative inactivation of ENO1, GLUL and PIN1 may alter these cellular processes and lead to the development of AD from MCI. We conclude that protein oxidation plays a significant role in the development of AD from MCI and that the oxidative inactivation of ENO1, GLUL, PKM2 and PIN1 is involved in the progression of AD from MCI. The current study provides a framework for future studies on the development of AD from MCI relevant to oxidative stress.

Protein oxidation has been shown to lead to loss of protein function, increased protein aggregation, decreased protein turnover, decreased membrane fluidity, altered cellular redox poteintial, loss of Ca 2+ homeostaisis, and cell death. There is increasing evidence that protein oxidation is involved in the pathogenesis of Alzheimer's disease and amyloid beta-peptide (1-42) has been implicated as a mediator of oxidative stress in AD. However, the specific implications of the oxidation induced by A␤(1-42) on the neurodegeneration evident in AD are unknown. In this study, we used proteomic techniques to identify specific targets of oxidation in transgenic Caenorhabditis elegans (C. elegans) expressing human A␤(1-42). We identified 16 oxidized proteins involved in energy metabolism, proteasome function, and scavenging of oxidants that are more oxidized compared to control lines. These results are discussed with reference to Alzheimer's disease.

Oxidized low density lipoprotein (OxLDL) possesses several proatherogenic characteristics, among which a marked cytotoxicity. In vitro, cytotoxicity of OxLDL to endothelial cells is associated with an increase in the expression of the inducible form of heat shock protein 70 (hsp70), generally regarded as a cytoprotective protein. Oxidized derivatives of cholesterol which form upon LDL oxidation are cytotoxic. Moreover, most of the OxLDL cytotoxicity is due to its lipid moiety, in particular to oxysterols. In this report we demonstrate that although oxysterols identified in OxLDL are cytotoxic, they cannot trigger the increase in hsp70 expression observed with intact oxidized lipoproteins. We speculate therefore that oxysterols may represent the most toxic form of oxidized lipids in LDL because they cannot activate a rescue mechanism (i.e. the hsp response) and may contribute significantly to cell death within atherosclerotic plaques.

High intensity ultrasound (HIUS) can promote Maillard reaction (MR). Macromolecular crowding conditions accelerate reactions and stabilize protein structure. The aim of this study was to investigate if combined application of ultrasound and macromolecular crowding can improve efficiency of MR. The presence of crowding agent (polyethylenglycole) significantly increased ultrasound-induced whey protein (WP) glycation by arabinose. An increase in glycation efficiency results only in slight change of WP structure. Macromolecular crowding intensifies oxidative modifications of WP, as well as formation of amyloid-like structures by enhancement of MR. Solubility at different pH, thermal stability and antioxidative capacity of glycated WP were increased, especially in the presence of crowding agent, compared to sonicated nonglycated proteins. The application of HIUS under crowding conditions can be a new approach for enhancement of reactions in general, enabling short processing time and mild conditions, while preserving protein structure and minimizing protein aggregation.

The intracellular mechanisms involved in the early phase of dendritic cell (DC) activation upon contact with chemical sensitizers are not well known. The strong skin sensitizer 2,4‐dinitrofluorobenzene (DNFB) was shown to induce the activation of mitogen‐activated protein kinases (MAPK) in DC. In the present study, we investigated a putative role for oxidative stress in DNFB‐induced MAPK activation and upregulation of the costimulatory molecule CD40. In a DC line generated from fetal mouse skin, DNFB induced a significant increase in protein oxidation, measured by the formation of carbonyl groups, while it had almost no effect on lipid peroxidation. The antioxidants glutathione and vitamin E, which inhibit protein and lipid oxidation, respectively, were used to assess the role of oxidative stress in DNFB‐induced MAPK activation. Glutathione, but not vitamin E, inhibited DNFB‐induced p38 MAPK and ERK1/2 phosphorylation, whereas none of the antioxidants interfered significantly with t...

Root-zone salinity stress and high solar irradiance concomitantly occurs in the Mediterranean basin, where Olea europaea is the dominating fruit-tree crop-species. Although the effect of each individual stressor on plant performance has been widely investigated, much less is known on the interaction effects of salinity stress and solar irradiance on the physiology and biochemistry of olive plants. Here we analyzed how changes in root-zone NaCl concentration and sunlight radiation affect relevant physiological and biochemical features in olive cv. Cipressino. Two-year-old plants were supplied with 0 or 125 mM NaCl and exposed to 15% (shade) or 100% sunlight (sun) over a 5-week period, starting from July 10th, 2005. Measurements were conducted of (i) gas exchange and plant growth, (ii) the concentrations of cations and chloride, (iii) the concentrations of soluble carbohydrates, violaxanthin-cycle pigments and polyphenols, and (iv) the protein oxidation and the lipid peroxidation in the leaves. Salt-induced reductions in gas exchange performance and plant growth were greater at the sun than at the shade site, mostly due to light-induced changes in leaf water relations and vapour pressure deficit (vpd), rather than in the concentration of potentially toxic ions. Light-induced increases in leaf Na + and Cl − concentrations were countered by parallel enhancements in the concentrations of K + and Ca 2+. Sun leaves had sharply greater concentrations of mannitol and xanthophylls, irrespective of root-zone salinity. The amount of "newly assimilate carbon" allocated to polyphenols, especially to flavonoids, increased in response to salinity stress and high sunlight. Remarkably, the protein oxidation was greater in shade than in sun leaves of well-watered plants, and increased more at the shade than at the sun site because of high salinity. We suggest that heat-stress (on average maximum T exceeded 33 • C for 50% of the experimental period), which acted in concert with salinity stress and sunlight irradiance in determining plant responses in our experiment, was responsible for leaf oxidative damage in plants growing under contrasting solar radiation. Indeed, sun leaves of salt-stressed plants were equipped with an extraordinary-rich arsenal of antioxidant compounds, distributed in different cell compartments, i.e., mannitol, zeaxanthin and flavonoids, which likely countered effectively the oxidative damage driven by heat-stress, a clear example of cross-tolerance.

Chemical transformations of the aminobutenes (1,2) were studied. Their allyl cationic intramolecular cyclisation led to the preparation of new tetrahydro-2-benzazepines containing a pyridine ring (3,4). The acylation and oxidation reactions of these aminobutenes gave several amides (5,6,8) and nitrone (7a), which was converted into the 6-phenyl-2-(3-pyridyl)-7-oxa-l-azabicyclo[2.2.1]heptane (9a).

Changes in the conformation of apoliprotein B-100 in the early stages of copper-mediated low density lipoprotein oxidation have been monitored by infrared spectroscopy. During the lag phase no variation in structure is observed, indicating that copper binding to the protein does not significantly affect its structure. In the propagation phase, while hydroperoxides are formed but the protein is not modified, no changes in secondary structure are observed, but the thermal profile of the band corresponding to ␣-helix is displaced in frequency, indicating changes in tertiary structure associated with this conformation but not with ␤-sheet components. When aldehyde formation starts, a decrease of ϳ 3% in the area of bands corresponding to ␣-helix and ␤-sheet is produced, concomitantly with an increase in ␤-turns and unordered structure. The two bands corresponding to ␤-turns vary as well under these conditions, indicating changes in these structures. Also at this stage the thermal profile shows variations in frequency for the bands corresponding to both ␣-helix and ␤-sheet. The results are consistent with the hypothesis that as soon as the polyunsaturated fatty acids from the particle core are modified, this change is reflected at the surface, in the ␣-helical components contacting the monolayer.

Nasal contribution to exhaled nitric oxide at rest and during breathholding in humans. Am J Respir Crit Care Med 153: 829-836, 1996. 4) Dear JW, Scadding GK, Foreman JC: Reduction by NG-nitro-L-arginine methyl ester (L-NAME) of antigen-induced nasal airway plasma extravasation in

Oxidation in food is a process that concerns both lipids and proteins by the effect of reactive oxygen species (ROS) (Bernardini et al., 2011). Oxidative modifications can cause numerous functional consequences and lead to changes in food texture, water holding capacity (WHC), digestibility and juiciness in fish meat (Baron, Kjaersgard, Jessen, & Jacobsen, 2007). Also, Sarma, Reddy, and Srikar (2000) found a negative correlation between lipid oxidation parameters and functional properties of the protein in Indian oil sardine, indicating their interdependence. However, still little is known about the kinetics of protein oxidation, the interaction of protein and lipid oxidation and the subsequent impact on muscle food quality (Baron et al., 2007; Kjaersgard & Jessen, 2004). For many years, the focus of food was on lipid oxidation, not only because of its effect on taste and shelf life, but also because the lipid oxidation products can more easily be measured (hydroperoxides, hexanal and MDA) than protein oxidation product and therefore have been detected and correlated to off-flavour in food. Especially in fish, which is rich in n-3 polyunsaturated fatty acids (PUFA), there is a high risk of quality loss due to oxidation (Jeremiah, 2001; Medina, Gallardo, & Aubourg, 2009). Besides lipid oxidation, the oxidation of proteins can also cause quality changes in the fish fillet. In general, the same factors causing lipid oxidation will also cause protein