Comparison of the effects of ozone on the modification of amino acid residues in glutamine synthetase and bovine serum albumin

Molecular Chaperones as Therapeutic Target: Hallmark of Neurodegenerative Disorders

Misfolded and aggregated proteins build up in neurodegenerative illnesses, which causes neuronal dysfunction and ultimately neuronal death. In the last few years, there has been a significant upsurge in the level of interest towards the function of molecular chaperones in the control of misfolding and aggregation. The crucial molecular chaperones implicated in neurodegenerative illnesses are covered in this review article, along with a variety of their different methods of action. By aiding in protein folding, avoiding misfolding, and enabling protein breakdown, molecular chaperones serve critical roles in preserving protein homeostasis. By aiding in protein folding, avoiding misfolding, and enabling protein breakdown, molecular chaperones have integral roles in preserving regulation of protein balance. It has been demonstrated that aging, a significant risk factor for neurological disorders, affects how molecular chaperones function. The aggregation of misfolded proteins and the development of neurodegeneration may be facilitated by the aging-related reduction in chaperone activity. Molecular chaperones have also been linked to the pathophysiology of several instances of neuron withering illnesses, enumerating as Parkinson's disease, Huntington's disease, and Alzheimer's disease. Molecular chaperones have become potential therapy targets concerning with the prevention and therapeutic approach for brain disorders due to their crucial function in protein homeostasis and their connection to neurodegenerative illnesses. Protein homeostasis can be restored, and illness progression can be slowed down by methods that increase chaperone function or modify their expression. This review emphasizes the importance of molecular chaperones in the context of neuron withering disorders and their potential as therapeutic targets for brain disorders.

Chloroplast ROS and stress signaling

Chloroplasts overproduce reactive oxygen species (ROS) under unfavorable environmental conditions, and these ROS are implicated in both signaling and oxidative damage. There is mounting evidence for their roles in translating environmental fluctuations into distinct physiological responses, but their targets, signaling cascades, and mutualism and antagonism with other stress signaling cascades and within ROS signaling remain poorly understood. Great efforts made in recent years have shed new light on chloroplast ROS-directed plant stress responses, from ROS perception to plant responses, in conditional mutants of Arabidopsis thaliana or under various stress conditions. Some articles have also reported the mechanisms underlying the complexity of ROS signaling pathways, with an emphasis on spatiotemporal regulation. ROS and oxidative modification of affected target proteins appear to induce retrograde signaling pathways to maintain chloroplast protein quality control and signaling at a whole-cell level using stress hormones. This review focuses on these seemingly interconnected chloroplast-to-nucleus retrograde signaling pathways initiated by ROS and ROS-modified target molecules. We also discuss future directions in chloroplast stress research to pave the way for discovering new signaling molecules and identifying intersectional signaling components that interact in multiple chloroplast signaling pathways.

Attenuation of arsenic induced high fat diet exacerbated oxidative stress mediated hepatic and cardiac injuries in male Wistar rats by piperine involved antioxidative mechanisms

The current study explored the efficacy of piperine in attenuating arsenic induced high fat diet aggravated oxidative stress mediated injury in hepatic and cardiac tissues of male Wistar rats. Oral administration of piperine significantly (p < 0.05) reduced the levels of organ specific and oxidative stress biomarkers in arsenic and high fat diet treated rat hepatic and cardiac tissues in a dose dependant manner with the dose of 60 mg/kg b.w. exhibiting maximum protection. Arsenic induced high fat diet aggravated oxidative stress mediated damages in liver and heart tissues led to decreased activities of antioxidant enzymes, ROS generation, diminished activities of Krebs' cycle and respiratory chain enzymes, collapsed mitochondrial membrane potential, mitochondrial DNA damage along with altered lipid metabolism and inflammatory cytokine levels. Histochemical and histopathological studies supported the above findings. Piperine efficiently counteracted the arsenic induced high fat diet aggravated oxidative stress mediated damages by modulating antioxidant defense mechanism along with free radical quenching ability. These findings indicate that piperine protected the arsenic induced high fat diet aggravated hepatic and cardiac injuries which underline the importance of piperine in providing a possible therapeutic regime for the amelioration of arsenic-induced high fat diet aggravated oxidative stress mediated organ damages.

Lung macrophages: current understanding of their roles in Ozone-induced lung diseases

Through the National Ambient Air Quality Standards (NAAQS), the Clean Air Act of the United States outlines acceptable levels of six different air pollutants considered harmful to humans and the environment. Included in this list is ozone (O₃), a highly reactive oxidant gas, respiratory health hazard, and common environmental air pollutant at ground level. The respiratory health effects due to O₃ exposure are often associated with molecular and cellular perturbations in the respiratory tract. Periodic review of NAAQS requires comprehensive scientific evaluation of the public health effects of these pollutants, which is formulated through integrated science assessment (ISA) of the most policy-relevant scientific literature. This review focuses on the protective and pathogenic effects of macrophages in the O₃-exposed respiratory tract, with emphasis on mouse model-based toxicological studies. Critical findings from 39 studies containing the words O₃, macrophage, mice, and lung within the full text were assessed. While some of these studies highlight the presence of disease-relevant pathogenic macrophages in the airspaces, others emphasize a protective role for macrophages in O₃-induced lung diseases. Moreover, a comprehensive list of currently known macrophage-specific roles in O₃-induced lung diseases is included in this review and the significant knowledge gaps that still exist in the field are outlined. In conclusion, there is a vital need in this field for additional policy-relevant scientific information, including mechanistic studies to further define the role of macrophages in response to O₃.

Copper, dityrosine cross-links and amyloid-β aggregation

Copper is involved in Alzheimer's disease (AD) where it appears to affect the aggregation of amyloid-β (Aβ) and to catalyze the production of reactive oxygen species (ROS). Oxidative stress apparently produces Aβ dimers that are covalently linked through two tyrosine residues. Such dityrosine cross-links are considered as potential markers of the disease and seem to be implicated in the pathological disorder. In the present study, pure o,o'-dityrosine (diY) was prepared enzymatically (with horseradish peroxidase; HRP), which was subsequently used to construct calibration lines aimed at quantifying nanomolar amounts of diY in reaction mixtures by fluorescence spectroscopy. Hence, diY concentrations down to 67 nM could be determined, which allowed to find that ca. 3% of dityrosine-bridged dimers of Aβ(1-40) were produced after 3 days at 37 °C in the presence of copper and dihydrogen peroxide. These cross-linked dimers in the presence of copper(II) ions completely inhibit the typical aggregation of Aβ, since β sheets could not be detected applying the usual Thioflavin T (ThT) method. Furthermore, the use of a potent Cu(II) chelator, such as the ATCUN tripeptide, L-histidyl-L-alanyl-L-histidine (HAH), efficiently prevented the copper-mediated generation of ROS and the associated dityrosine-bridged Aβ dimers, suggesting that such metal chelators may find future applications in the field of anti-AD drug design.

Chemical Basis of Reactive Oxygen Species Reactivity and Involvement in Neurodegenerative Diseases

Increasing numbers of individuals suffer from neurodegenerative diseases, which are characterized by progressive loss of neurons. Oxidative stress, in particular, the overproduction of Reactive Oxygen Species (ROS), play an important role in the development of these diseases, as evidenced by the detection of products of lipid, protein and DNA oxidation in vivo. Even if they participate in cell signaling and metabolism regulation, ROS are also formidable weapons against most of the biological materials because of their intrinsic nature. By nature too, neurons are particularly sensitive to oxidation because of their high polyunsaturated fatty acid content, weak antioxidant defense and high oxygen consumption. Thus, the overproduction of ROS in neurons appears as particularly deleterious and the mechanisms involved in oxidative degradation of biomolecules are numerous and complexes. This review highlights the production and regulation of ROS, their chemical properties, both from kinetic and thermodynamic points of view, the links between them, and their implication in neurodegenerative diseases.

Nontarget Biomolecules Alter Macromolecular Changes Induced by Bactericidal Low-Temperature Plasma

Low-temperature plasmas (LTPs) have a proven bactericidal activity governed by the generated reactive oxygen and nitrogen species (RONS) that target microbial cell components. However, RONS also interact with biomolecules in the environment. Here we assess the impact of these interactions upon exposure of liquid suspensions with variable organic content to an atmospheric-pressure dielectric barrier discharge plasma jet. Salmonella enterica serovar Typhimurium viability in the suspension was reduced in the absence [e.g., phosphate buffered saline (PBS)], but not in the presence of (high) organic content [Dulbecco's Modified Eagle's Medium (DMEM), DMEM supplemented with foetal calf serum, and Lysogeny Broth]. The reduced viability of LTP-treated bacteria in PBS correlated to a loss of membrane integrity, whereas double-strand DNA breaks could not be detected in treated single cells. The lack of bactericidal activity in solutions with high organic content correlated with a relative decrease of ^•OH and O₃/O₂(a¹\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}${\Delta }\text{g}$ \end{document})/O, and an increase of H₂O₂ and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\mathrm{NO}_{2}^{-}$ \end{document} in the plasma-treated solutions. These results indicate that the redox reactions of LTP-generated RONS with nontarget biomolecules resulted in a RONS composition with reduced bactericidal activity. Therefore, the chemical composition of the bacterial environment should be considered in the development of LTP for antimicrobial treatment, and may affect other biomedical applications as well.

Improvement of proteolytic and oxidative stability of Chondroitinase ABC I by cosolvents

Recently, utilization of the enzyme Chondroitinase ABC I (cABC I) has received considerable attention in treatment of spinal cord injury. cABC I removes chondroitin sulfate proteoglycans which are inhibitory to axon growth and enhances nerve regeneration. Therefore, determination of cABC I resistance to proteolysis and oxidation provides valuable information for optimizing its clinical application. In this work, proteolytic stability of cABC I to trypsin and chymotrypsin as well as its oxidative resistance to H2O2 was measured. Moreover, the effect of cosolvents glycerol, sorbitol and trehalose on cABC I proteolytic and oxidative stability was determined. The results indicated that cABC I is highly susceptible to proteolysis and oxidation. Comparison of proteolytic patterns demonstrated a high degree of similarity which confirmed the exposure of specific regions of cABC I to proteolysis. However, proteolytic degradation was significantly reduced in the presence of cosolvents. In addition, cosolvents decreased the rate of both cABC I proteolytic and oxidative inactivation. Notably, the degree of stabilization provided by these cosolvents varied greatly. These findings indicated the high potential of cosolvents in protein stabilization to proteolysis and oxidative inactivation.

Fibrin self-assembly is adapted to oxidation

Fibrinogen is extremely susceptible to attack by reactive oxygen species (ROS). Having been suffered an oxidative modification, the fibrinogen molecules, now with altered spatial structure and function of fibrin network, affect hemostasis differently. However, the potential effects of the oxidative stress on the early stages of the fibrin self-assembly process remain unexplored. To clarify the damaging influence of ROS on the knob 'A': hole 'a' and the D:D interactions, the both are operating on the early stages of the fibrin polymerization, we have used a novel approach based on exploration of FXIIIa-mediated self-assembly of the cross-linked fibrin oligomers dissolved in the moderately concentrated urea solutions. The oligomers were composed of monomeric desA fibrin molecules created by cleaving the fibrinopeptides A off the fibrinogen molecules with a thrombin-like enzyme, reptilase. According to the UV-absorbance and fluorescence measurements data, the employed low ozone/fibrinogen ratios have induced only a slight fibrinogen oxidative modification that was accompanied by modest chemical transformations of the aromatic amino acid residues of the protein. Else, a slight consumption of the accessible tyrosine residues has been observed due to intermolecular dityrosine cross-links formation. The set of experimental data gathered with the aid of electrophoresis, elastic light scattering and analytical centrifugation has clearly witnessed that the oxidation can serve as an effective promoter for the observed enhanced self-assembly of the covalently cross-linked oligomers. At urea concentration of 1.20M, the pristine and oxidized fibrin oligomers were found to comprise a heterogeneous set of the double-stranded protofibrils that are cross-linked only by γ-γ dimers and the fibers consisting on average of four strands that are additionally linked by α polymers. The amounts of the oxidized protofibrils and the fibers accumulated in the system were higher than those of the non-oxidized counterparts. Moreover, the γ and α polypeptide chains of the oxidized molecules were more readily crosslinked by the FXIIIa. Upon increasing the urea solution concentration to 4.20M, the cross-linked double-stranded desA fibrin protofibrils have dissociated into the single-stranded fibrin oligomers, whereas the fibers dissociated into both the double-stranded desA fibrin oligomers, the structural integrity of the latter being maintained by means of the intermolecular α polymers, and the single-stranded fibrin oligomers cross-linked only by γ-γ dimers. The data we have obtained in this study indicate that the FXIIIa-mediated process of assembling the cross-linked protofibrils and the fibers constructed from the oxidized monomeric fibrin molecules was facilitated due to the strengthening of D:D interactions. The findings infer that the enhanced longitudinal D:D interactions become more essential in the assembly of soluble protofibrils when the interactions knobs 'A': holes 'a' are injured by oxidation. The new experimental findings presented here could be of help for elucidating the essential adaptive molecular mechanisms capable of mitigating the detrimental action of ROS in the oxidatively damaged fibrin self-assemblage processes.

Identification of Highly Pathogenic Microorganisms by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry: Results of an Interlaboratory Ring Trial

In the case of a release of highly pathogenic bacteria (HPB), there is an urgent need for rapid, accurate, and reliable diagnostics. MALDI-TOF mass spectrometry is a rapid, accurate, and relatively inexpensive technique that is becoming increasingly important in microbiological diagnostics to complement classical microbiology, PCR, and genotyping of HPB. In the present study, the results of a joint exercise with 11 partner institutions from nine European countries are presented. In this exercise, 10 distinct microbial samples, among them five HPB, Bacillus anthracis, Brucella canis, Burkholderia mallei, Burkholderia pseudomallei, and Yersinia pestis, were characterized under blinded conditions. Microbial strains were inactivated by high-dose gamma irradiation before shipment. Preparatory investigations ensured that this type of inactivation induced only subtle spectral changes with negligible influence on the quality of the diagnosis. Furthermore, pilot tests on nonpathogenic strains were systematically conducted to ensure the suitability of sample preparation and to optimize and standardize the workflow for microbial identification. The analysis of the microbial mass spectra was carried out by the individual laboratories on the basis of spectral libraries available on site. All mass spectra were also tested against an in-house HPB library at the Robert Koch Institute (RKI). The averaged identification accuracy was 77% in the first case and improved to >93% when the spectral diagnoses were obtained on the basis of the RKI library. The compilation of complete and comprehensive databases with spectra from a broad strain collection is therefore considered of paramount importance for accurate microbial identification.

Sweet grass protection against oxidative stress formation in the rat brain

The aims of this study were to investigate the influences of sweet grass on chronic ethanol-induced oxidative stress in the rat brain. Chronic ethanol intoxication decreased activities and antioxidant levels resulting in enhanced lipid peroxidation. Administration of sweet grass solution to ethanol-intoxicated rats partially normalized the activity activities of Cu,Zn-superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, as well as levels of reduced glutathione and vitamins C, E, and A. Sweet grass also protected unsaturated fatty acids (arachidonic and docosahexaenoic) from oxidations and decreased levels of lipid peroxidation products: 4-hydroxynonenal, isoprostanes, and neuroprostanes. The present in vivo study confirms previous in vitro data demonstrating the bioactivity of sweet grass and suggests a possible role for sweet grass in human health protection from deleterious consequences associated with oxidative stress formation.

Ozone-induced oxidative modification of fibrinogen molecules

Ozone-induced oxidation of fibrinogen has been investigated. The conversion of oxidized fibrinogen to fibrin catalyzed either by thrombin or by a reptilase-like enzyme, ancistron, in both cases is accompanied by production of gels characterized by a higher weight/length ratio of fibrils in comparison with the native fibrin gels. IR spectra of the D and E fragments isolated from unoxidized and oxidized fibrinogen suggest a noticeable transformation of functional groups by oxidation. A decrease in content of N-H groups in the peptide backbone and in the number of C-H bonds in aromatic structures, as well as a decrease in the intensity of the C-H valence vibrations in aliphatic fragments CH2 and CH3 were found. The appearance in the differential spectra of the D fragments of rather intense peaks in the interval of 1200-800 cm(-1) clearly indicates the interaction of ozone with amino acid residues of methionine, tryptophan, histidine, and phenylalanine. Comparison of the differential spectra for the D and E fragments suggests that fibrinogen fragment D is more sensitive to the oxidant action than fragment E. Using EPR spectroscopy, differences are found in the spectra of spin labels bound with degradation products of oxidized and unoxidized fibrinogen, the D and E fragments, caused by structural and dynamical modifications of the protein molecules in the areas of localization of the spin labels. The relationship between the molecular mechanism of oxidation of fibrinogen and its three-dimensional structure is discussed.

Ozone-induced oxidative modification of fibrinogen: role of the D regions

Native fibrinogen is a key blood plasma protein whose main function is to maintain hemostasis by virtue of producing cross-linked fibrin clots under the influence of thrombin and fibrin-stabilizing factor (FXIIIa). The aim of this study was to investigate mechanisms of impairment of both the molecular structure and the spatial organization of fibrinogen under ozone-induced oxidation. FTIR analysis showed that ozone treatment of the whole fibrinogen molecule results in the growth of hydroxyl, carbonyl, and carboxyl group content. A similar analysis of fibrinogen D and E fragments isolated from the oxidized protein also revealed transformation of distinct important functional groups. In particular, a remarkable decay of N-H groups within the peptide backbone was observed along with a lowering of the content of C-H groups belonging to either the aromatic moieties or the aliphatic chain CH2 and CH3 units. The model experiments performed showed that the rather unexpected decay of the aliphatic CH units might be caused by the action of hydroxyl radicals, these being produced in the water solution from ozone. The observed dissimilarities in the shapes of amide I bands of the fibrinogen D and E fragments before and after ozone treatment are interpreted in terms of feasible local conformational changes affecting the secondary structure of the protein. Taken as a whole, the FTIR data suggests that the terminal D fragments of fibrinogen are markedly more susceptible to the ozone-induced oxidation than the central E fragment. The data on elastic and dynamic light scattering provide evidence that, in the presence of FXIIIa, both the unoxidized and the oxidized fibrinogen molecules bind to one another in an "end-to-end" fashion to form the flexible covalently cross-linked fibrinogen homopolymers. The γ and α polypeptide chains of the oxidized fibrinogen proved to be involved in the enzymatic cross-linking more readily than those of unaffected fibrinogen. The experimental data on fibrinogen oxidation acquired in the present study, combined with our earlier findings, make it reasonable to suppose that the spatial structure of fibrinogen could be evolutionarily adapted to some reactive oxygen species actions detrimental to the protein function.

Conformational study reveals amino acid residues essential for hemagglutinating and anti-proliferative activities of Clematis montana lectin

Clematis montana lectin (CML), a novel mannose-binding lectin purified from C. montana Buch.-Ham stem (Ranunculaceae), has been proved to have hemagglutinating activity in rabbit erythrocytes and apoptosis-inducing activity in tumor cells. However, the biochemical properties of CML have not revealed and its structural information still needs to be elucidated. In this study, it was found that CML possessed quite good thermostability and alkaline resistance, and its hemagglutinating activity was bivalent metal cation dependent. In addition, hemagglutination test and fluorescence spectroscopy proved that GuHCl, urea, and sodium dodecyl sulfate could change the conformation of CML and further caused the loss of hemagglutination activity. Moreover, the changes of fluorescence spectrum indicated that the tryptophan (Trp) microenvironment conversion might be related to the conformation and bioactivities of CML. In addition, it was also found that Trp residues, arginine (Arg) residues, and sulfhydryl were important for the hemagglutinating activity of CML, but only Trp was proved to be crucial for the CML conformation. Furthermore, the Trp, Arg, and sulfhydryl-modified CML exhibited 97.17%, 76.99%, and 49.64% loss of its anti-proliferative activity, respectively, which was consistent with the alterations of its hemagglutinating activity. Given these findings, Trp residues on the surface of CML are essential for the active center to form substrate-accessible conformation and suitable environment for carbohydrate binding.

Effects of heat treatment of soy protein isolate on the growth performance and immune function of broiler chickens

This study was conducted to evaluate the effects of oxidative modification of soy protein isolate (SPI) after exposure to heat on the growth performance and immune function of broilers. The SPI was heated in an oven at 100°C for 1, 4, and 8 h, respectively, and resultant oxidative status was evaluated. A total of 320 one-day-old Arbor Acres chickens were randomly divided into 4 treatment groups with 8 replicates of 10 birds, and fed diets supplemented with the native SPI or 1 of the 3 heat-treated SPI for 21 d. The results showed that heat exposure of SPI for 4 and 8 h caused an increase in protein carbonyl (P < 0.05), and a simultaneous decrease in sulfhydryl and free amine groups (P < 0.05) compared with native SPI. The BW of broilers fed diets supplemented with SPI heated for 8 h were significantly lower than that of broilers fed diets supplemented with native SPI (P < 0.05). Compared with native SPI, heat-treated SPI (heated for 8 h) diminished liver weight at 14 d (P = 0.01), spleen (P < 0.01) and bursa (P < 0.05) weights at 21 d; and the content of IgG in serum and duodenal mucosa of broilers (at 14 d) was decreased when diets supplemented with heat-treated SPI (heated for 8 h; P < 0.01). No significant differences were observed in the mucosa secretory IgA contents of broilers among the treatment groups (P > 0.05). Compared with native SPI, a significant increases were observed in the content of adrenocorticotropic hormone and cortisol in serum of broilers fed the heat-treated SPI (heated for 8 h) at 21 d (P < 0.05); and the myeloperoxidase activities in serum (at 14 d) and mucosa of broilers were increased when diets supplemented with heat-treated SPI (heated for 8 h; P < 0.05). The present study suggests that protein oxidation of SPI is induced by heating, and oxidized protein may negatively affect the immune function of broilers.

Changes in fluorescence spectra of bioaerosols exposed to ozone in a laboratory reaction chamber to simulate atmospheric aging

A laboratory system for exposing aerosol particles to ozone and rapidly measuring the subsequent changes in their single-particle fluorescence is reported. The system consists of a rotating drum chamber and a single-particle fluorescence spectrometer (SPFS) utilizing excitation at 263 nm. Measurements made with this system show preliminary results on the ultra-violet laser-induced-fluorescence (UV-LIF) spectra of single aerosolized particles of Yersinia rohdei, and of MS2 (bacteriophage) exposed to ozone. When bioparticles are exposed in the chamber the fluorescence emission peak around 330 nm: i) decreases in intensity relative to that of the 400-550 nm band; and ii) shifts slightly toward shorter-wavelengths (consistent with further drying of the particles). In these experiments, changes were observed at exposures below the US Environmental Protection Agency (EPA) limits for ozone.

Protein damage, repair and proteolysis

Proteins are continuously affected by various intrinsic and extrinsic factors. Damaged proteins influence several intracellular pathways and result in different disorders and diseases. Aggregation of damaged proteins depends on the balance between their generation and their reversal or elimination by protein repair systems and degradation, respectively. With regard to protein repair, only few repair mechanisms have been evidenced including the reduction of methionine sulfoxide residues by the methionine sulfoxide reductases, the conversion of isoaspartyl residues to L-aspartate by L-isoaspartate methyl transferase and deglycation by phosphorylation of protein-bound fructosamine by fructosamine-3-kinase. Protein degradation is orchestrated by two major proteolytic systems, namely the lysosome and the proteasome. Alteration of the function for both systems has been involved in all aspects of cellular metabolic networks linked to either normal or pathological processes. Given the importance of protein repair and degradation, great effort has recently been made regarding the modulation of these systems in various physiological conditions such as aging, as well as in diseases. Genetic modulation has produced promising results in the area of protein repair enzymes but there are not yet any identified potent inhibitors, and, to our knowledge, only one activating compound has been reported so far. In contrast, different drugs as well as natural compounds that interfere with proteolysis have been identified and/or developed resulting in homeostatic maintenance and/or the delay of disease progression.

In vitro exposure of proteins to ozone

An in vitro system has been developed to expose proteins to ozone. The system is designed to deliver consistent and accurate levels of ozone over a range of concentrations (between 0.1 and >/=10 ppm) with extended exposure times (24 h or longer) in a humidified environment (100%). In the experiment presented in this article, ozone concentrations between 0.1 and 2.0 ppm were used. Ozone was generated by an electrical discharge ozonizer to ensure stability; it was continually monitored by an ultraviolet ozone analyzer and was precisely controlled by mass flow controllers, which gave reproducible results between runs. Humidity was closely regulated in the system to allow small amounts of protein solutions (50 muL or less) to be exposed without significant changes (<0.2%) in sample volume. The degree of surfactant protein-A (SP-A) oxidation by ozone was measured between runs to demonstrate the reproducibility of the system. A detailed description of the system is given, and protein oxidation detection methods and their limitations are discussed. Using these methods, we were able to assess oxidation of SP-A that apparently occurred prior to its isolation from the lung by bronchoalveolar lavage. This in vitro system allowed us to expose small amounts of protein to ozone in a simple, highly controlled, and reproducible manner.

Quantitation of protein carbonylation by dot blot

Protein carbonylation is the most commonly used measure of oxidative modification of proteins. It is frequently measured spectrophotometrically or immunochemically by derivatizing proteins with the classical carbonyl reagent, 2,4-dinitrophenylhydrazine. We developed an immunochemical dot blot method for quantitation of protein carbonylation in homogenates or purified proteins. Dimethyl sulfoxide was employed as the solvent because it very efficiently extracts proteins from tissues and keeps them soluble. It also readily dissolves 2,4-dinitrophenylhydrazine and wets polyvinylidene difluoride (PVDF) membranes. The detection limit is 0.19 ± 0.04 pmol of carbonyl, and 60 ng of protein is sufficient to measure protein carbonyl content. This level of sensitivity allowed measurement of protein carbonylation in individual Drosophila.

The amylin peptide implicated in type 2 diabetes stimulates copper-mediated carbonyl group and ascorbate radical formation

Human amylin (hA), which is toxic to islet β-cells, can self-generate H(2)O(2), and this process is greatly enhanced in the presence of Cu(II) ions. Here we show that carbonyl groups, a marker of oxidative modification, were formed in hA incubated in the presence of Cu(II) ions or Cu(II) ions plus H(2)O(2), but not in the presence of H(2)O(2) alone. Furthermore, under similar conditions (i.e., in the presence of both Cu(II) ions and H(2)O(2)), hA also stimulated ascorbate radical formation. The same observations concerning carbonyl group formation were made when the histidine residue (at position 18) in hA was replaced by alanine, indicating that this residue does not play a key role. In complete contrast to hA, rodent amylin, which is nontoxic, does not generate H(2)O(2), and binds Cu(II) ions only weakly, showed none of these properties. We conclude that the hA-Cu(II)/Cu(I) complex is redox active, with electron donation from the peptide reducing the oxidation state of the copper ions. The complex is capable of forming H(2)O(2) from O(2) and can also generate (•)OH via Fenton chemistry. These redox properties of hA can explain its ability to stimulate copper-mediated carbonyl group and ascorbate radical formation. The formation of reactive oxygen species from hA in this way could hold the key to a better understanding of the damaging consequences of amyloid formation within the pancreatic islets of patients with type 2 diabetes mellitus.

Quality of bread made from ozonated wheat (Triticum aestivum L.) flour

BACKGROUND

Ozone gas could be used as a fumigant during grain and flour storage. Experiments were conducted to determine the effects of exposure to ozone and the effects of blending ozone-treated flour with control flour on flour functionality and bread-making quality.

RESULTS

Ozone treatment oxidized lipids, increased brightness and reduced the yellow hue of flour, and increased peak viscosity and setback viscosity of flour. Bread made from flour treated with ozone at 1500 mg kg(-1) for 4.5 min and bread made from flour blended with 100 g kg(-1) ozonated flour had good crust color and a whiter crumb and had more crumb cells, which resulted in a greater specific volume of the bread when compared with control flour. Flour functionality declined as ozone exposure increased beyond 9 min and as the concentration of ozonated flour increased beyond 200 g kg(-1) .

CONCLUSION

Bread made from flour exposed to ozone for 4.5 min or flour that contained 100 g kg(-1) fully ozonated flour had greater specific loaf volume and whiter crumb compared to bread made with control flour. Exposure of flour to ozone for longer times (9-45 min) and higher blends (200-1000 g kg(-1) ) deteriorated quality of bread.

Oxidative protein labeling in mass-spectrometry-based proteomics

Oxidation of proteins and peptides is a common phenomenon, and can be employed as a labeling technique for mass-spectrometry-based proteomics. Nonspecific oxidative labeling methods can modify almost any amino acid residue in a protein or only surface-exposed regions. Specific agents may label reactive functional groups in amino acids, primarily cysteine, methionine, tyrosine, and tryptophan. Nonspecific radical intermediates (reactive oxygen, nitrogen, or halogen species) can be produced by chemical, photochemical, electrochemical, or enzymatic methods. More targeted oxidation can be achieved by chemical reagents but also by direct electrochemical oxidation, which opens the way to instrumental labeling methods. Oxidative labeling of amino acids in the context of liquid chromatography(LC)-mass spectrometry (MS) based proteomics allows for differential LC separation, improved MS ionization, and label-specific fragmentation and detection. Oxidation of proteins can create new reactive groups which are useful for secondary, more conventional derivatization reactions with, e.g., fluorescent labels. This review summarizes reactions of oxidizing agents with peptides and proteins, the corresponding methodologies and instrumentation, and the major, innovative applications of oxidative protein labeling described in selected literature from the last decade.

Fragmentation mechanisms of oxidized peptides elucidated by SID, RRKM modeling, and molecular dynamics

The gas-phase fragmentation reactions of singly charged angiotensin II (AngII, DR(+)VYIHPF) and the ozonolysis products AngII+O (DR(+)VY*IHPF), AngII+3O (DR(+)VYIH*PF), and AngII+4O (DR(+)VY*IH*PF) were studied using SID FT-ICR mass spectrometry, RRKM modeling, and molecular dynamics. Oxidation of Tyr (AngII+O) leads to a low-energy charge-remote selective fragmentation channel resulting in the b(4)+O fragment ion. Modification of His (AngII+3O and AngII+4O) leads to a series of new selective dissociation channels. For AngII+3O and AngII+4O, the formation of [MH+3O](+)-45 and [MH+3O](+)-71 are driven by charge-remote processes while it is suggested that b(5) and [MH+3O](+)-88 fragments are a result of charge-directed reactions. Energy-resolved SID experiments and RRKM modeling provide threshold energies and activation entropies for the lowest energy fragmentation channel for each of the parent ions. Fragmentation of the ozonolysis products was found to be controlled by entropic effects. Mechanisms are proposed for each of the new dissociation pathways based on the energies and entropies of activation and parent ion conformations sampled using molecular dynamics.

Blood as a reactive species generator and redox status regulator during exercise

The exact origin of reactive species and oxidative damage detected in blood is largely unknown. Blood interacts with all organs and tissues and, consequently, with many possible sources of reactive species. In addition, a multitude of oxidizable substrates are already in blood. A muscle-centric approach is frequently adopted to explain reactive species generation, which obscures the possibility that sources of reactive species and oxidative damage other than skeletal muscle may be also at work during exercise. Plasma and blood cells can autonomously produce significant amounts of reactive species at rest and during exercise. The major reactive species generators located in blood during exercise may be erythrocytes (mainly due to their quantity) and leukocytes (mainly due to their drastic activation during exercise). Therefore, it is plausible to assume that oxidative stress/damage measured frequently in blood after exercise or any other experimental intervention derives, at least in part, from the blood.

Protein oxidation and aging

Organisms are constantly exposed to various forms of reactive oxygen species (ROS) that lead to oxidation of proteins, nucleic acids, and lipids. Protein oxidation can involve cleavage of the polypeptide chain, modification of amino acid side chains, and conversion of the protein to derivatives that are highly sensitive to proteolytic degradation. Unlike other types of modification (except cysteine oxidation), oxidation of methionine residues to methionine sulfoxide is reversible; thus, cyclic oxidation and reduction of methionine residues leads to consumption of ROS and thereby increases the resistance of proteins to oxidation. The importance of protein oxidation in aging is supported by the observation that levels of oxidized proteins increase with animal age. The age-related accumulation of oxidized proteins may reflect age-related increases in rates of ROS generation, decreases in antioxidant activities, or losses in the capacity to degrade oxidized proteins.

L-Carnitine in the lipid and protein protection against ethanol-induced oxidative stress

Chronic ethanol intoxication induces oxidative stress participating in the development of many diseases. Nutrition and the interaction of food nutrients with ethanol metabolism may modulate alcohol toxicity. One such compound is l-carnitine (l-3-hydroxy-4-N,N,N-trimethylaminobutyrate), which also reveals antioxidant abilities. The present study has been designed to investigate the effect of l-carnitine as an antioxidant on the serum and liver of rats chronically intoxicated with ethanol. Rats received l-carnitine solution (1.5g/1L) for 5 weeks and/or were treated intragastrically with ethanol for 4 weeks. In the serum and liver, the level of nonenzymatic antioxidants and lipid and protein oxidation markers were determined. It was shown that alcohol caused the increase in the level of lipid peroxidation products-conjugated dienes (by about 70% and 60% in the liver and blood serum, respectively), malondialdehyde (MDA) (by about 60% and 30% in the liver and blood serum, respectively), 4-hydroxynonenal (4-HNE) (by about 35% and 25% in the liver and blood serum, respectively), and changes in the level of protein oxidative markers-increase in dityrosine and decrease in tryptophan (by about 40%) in the serum and liver of rats. Moreover, the decrease in vitamin E level (by about 30%) and the level of glutathione (GSH) (by about 20% in the liver and blood serum) was also observed. Administration of l-carnitine to rats intoxicated with ethanol significantly protects lipids and proteins against oxidative modifications in the serum and liver. The level of conjugated dienes, MDA, and 4-HNE was decreased by about 30%, 30%, and 20% in the liver, respectively, and by about 20%, 10%, and 10% in the blood serum in comparison to the ethanol group. Moreover, the level of tryptophan was increased and dityrosine decreased by about 10% and 20% in the liver, respectively, and by about 30% and 10% in the blood serum in comparison to the ethanol group. l-carnitine partially protects nonenzymatic antioxidants against oxidative stress. The level of vitamin E was increased by about 20% and the level of GSH was increased by about 25% in the liver and blood serum in comparison to the ethanol group. It is possible that beneficial effect of l-carnitine is connected with its abilities to scavenge free radicals and to chelate metal ions.

The impact of atmospheric composition on plants: a case study of ozone and poplar

Tropospheric ozone is the main atmospheric pollutant that causes damages to trees. The estimation of the threshold for ozone risk assessment depends on the evaluation of the means that this pollutant impacts the plant and, especially, the foliar organs. The available results show that, before any visible symptom appears, carbon assimilation and the underlying metabolic processes are decreased under chronic ozone exposure. By contrast, the catabolic pathways are enhanced, and contribute to the supply of sufficient reducing power necessary to feed the detoxification processes. Reactive oxygen species delivered during ozone exposure serve as toxic compounds and messengers for the signaling system. In this review, we show that the contribution of genomic tools (transcriptomics, proteomics, and metabolomics) for a better understanding of the mechanistic cellular responses to ozone largely relies on spectrometric measurements.

Acid-induced change in ozone-reactive site in indole ring of tryptophan

It is well established that ozone as well as oxygen activated by tryptophan 2,3-dioxygenase or indoleamine 2,3-dioxygenase cleave the 2,3-C=C bond of the indole ring of tryptophan to produce N-formylkynurenine. In the present study, however, we found that exposure of tryptophan to aqueous ozone at and below pH 4.5 generated a different compound. The compound was identified as kynurenine by high performance liquid chromatography and mass spectrometry. Exposure of N-formylkynurenine to acidic ozone did not generate a significant amount of kynurenine, indicating that the kynurenine was not produced via N-formylkynurenine. Acidic ozone thus appears to cleave the 1, 2-NAC bond in place of the 2,3-C=C bond of the indole ring, followed by liberation of the 2-C atom. The 1,2-NAC bond and 2,3-C=C bond are likely to undergo changes in their nature of bonding on acidification, enabling ozone to react with the former bond but not with the latter bond.