Metal-catalyzed oxidation of proteins. Physiological consequences

Aminoadipic acid aggravates atherosclerotic vascular inflammation through ROS/TXNIP/NLRP3 pathway, a harmful microbial metabolite reduced by paeonol

AIM

Our previous study has found a differential microbial metabolite in atherosclerosis (AS) mice, aminoadipic acid (AAA), which was considered as a potential harmful metabolite. However, whether it can promote AS vascular inflammation and its mechanisms remain unclear. Paeonol (Pae) plays an anti-AS role by regulating the metabolic profile, but whether Pae exerts its antiatherogenic effect by reducing serum AAA levels is unknown.

RESULTS

The clinical trial results showed that the AS patients' serum AAA levels were higher than those healthy people'. Besides, AAA supplementation could increase aortic plaque size, serum inflammatory cytokines levels and liver malondialdehyde, superoxide dismutase levels in AS mice. Moreover, after AAA stimulation, the ROS levels and ASC, TXNIP, NLRP3 and caspase-1 proteins levels were increased in HUVECs, which could be reversed by antioxidant NAC and NLRP3 inhibitor. Pae significantly reduced the plaque size in the aorta, improved blood lipid levels and decreased serum inflammation factor levels in AS mice. Simultaneously, Pae could reduce the serum AAA levels of AS mice through the gut microbiota transmission. Finally, Pae inhibited NLRP3 inflammasome activation in aortas of AS mice. Broad-spectrum antibiotics could weaken the inhibitory effect of Pae on NLRP3 inflammasome.

CONCLUSION

Our study clarified that AAA could promote AS vascular inflammation via activating the ROS/TXNIP/NLRP3 pathway. Pae could inhibit AS development by reducing serum AAA levels in a microbiota-dependent manner. Taken together, we proposed that AAA could be served as a potential biomarker for AS clinical diagnosis and provided a new treatment strategy for AS.

Relationship between parental exposure to radiofrequency electromagnetic fields and primarily hematopoietic neoplasms (lymphoma, leukemia) and tumors in the central nervous system in children: a systematic review

Low-frequency electromagnetic fields have grown exponentially in recent years due to technological development and modernization. The World Health Organization (WHO)/International Agency for Research on Cancer (IARC) has classified radiofrequency electromagnetic fields (RF-EMFs) as possibly carcinogenic to humans (Group 2B), and recent studies have investigated the association between exposure to electromagnetic fields in parents and possible health effects in children, especially the development of tumours of the central nervous system (CNS). The objective of this systematic review was to collate all evidence on the relationship between parental occupational exposure to electromagnetic fields and the development of CNS cancer in children and to evaluate this association. This review was prepared according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed, Embase, and Web of Science were searched from January 1990 to April 2021. The search was conducted using the following search string: "occupational" AND "child" AND "electromagnetic" AND "cancer". Seventeen articles met our inclusion criteria: 13 case-control studies, two cohort studies, and 2 meta-analyses. Most of the studies showed several methodological weaknesses that limited their results. Due to a lack of consistency regarding the outcome as well as the heterogeneity in the reviewed studies, the body of evidence for the effects of parental exposure to electromagnetic fields is not clear. Methodological heterogeneity in the way that studies were conducted could be responsible for the lack of consistency in the findings. Overall, the body of evidence allows no conclusion on the relationship between parental exposure to electromagnetic fields and the occurrence of CNS tumours in children.

Oxidative stress induced conformational changes of human serum albumin

Oxidative stress, generated by reactive oxygen species (ROS), is responsible for the loss of structure and functionality of proteins and is associated with several aging-related diseases. Here, we report an in vitro study to gauge the effect of ROS on the structural rearrangement of human serum albumin (HSA), a plasma protein, through metal-catalyzed oxidation (MCO) at physiological temperature through various biophysical techniques like UV-vis absorption, circular dichroism (CD), differential scanning calorimetry (DSC), MALDI-TOF, FTIR, and Raman spectroscopy. The UV-vis spectra of oxidized HSA show an early blueshift, signifying the unfolding of the protein because of ROS followed by the broadening of the absorption peak at a longer time. The DSC data corroborate the observation, revealing an exothermic transition for the oxidized sample at a longer time, suggesting in situ aggregation. The CD and FTIR spectra indicate the associated secondary structural changes occurring with time, depicting the variation of the helical content of HSA. The amide-III analysis of Raman data also complements the structural changes, and MALDI-TOF data show the mass distribution with time. Overall, this work might help determine the effect of oxidation on the biological activity of serum albumin as it can impact the physiological properties of HSA.

Arabidopsis response to copper is mediated by density and root exudates: Evidence that plant density and toxic soils can shape plant communities

PREMISE

Plants grown at high densities show increased tolerance to heavy metals for reasons that are not clear. A potential explanation is the release of citrate by plant roots, which binds metals and prevents uptake. Thus, pooled exudates at high plant densities might increase tolerance. We tested this exclusion facilitation hypothesis using mutants of Arabidopsis thaliana defective in citrate exudation.

METHODS

Wild type Arabidopsis and two allelic mutants for the Ferric Reductase Defective 3 (FRD3) gene were grown at four densities and watered with copper sulfate at four concentrations. Plants were harvested before bolting and dried. Shoot biomass was measured, and shoot material and soil were digested in nitric acid. Copper contents were determined by atomic absorption.

RESULTS

In the highest-copper treatment, density-dependent reduction in toxicity was observed in the wild type but not in FRD3 mutants. For both mutants, copper concentrations per gram biomass were up to seven times higher than for wild type plants, depending on density and copper treatment. In all genotypes, total copper accumulation was greater at higher plant densities. Plant size variation increased with density and copper treatment because of heterogeneous distribution of copper throughout the soil.

CONCLUSIONS

These results support the hypothesis that citrate exudation is responsible for density-dependent reductions in toxicity of metals. Density-dependent copper uptake and growth in contaminated soils underscores the importance of density in ecotoxicological testing. In soils with a heterogeneous distribution of contaminants, competition for nontoxic soil regions may drive size hierarchies and determine competitive outcomes.

Structural rearrangement of elastin under oxidative stress

Reactive oxygen species (ROS) are key elements in several physiological processes. A high level of ROS leads to oxidative stress that damages biomolecules and is linked to many diseases like type-2 diabetes, cancer, inflammation, and many more. Here, our in-vitro study aimed to gauge the effect of ROS on the structural rearrangement of elastin through metal-catalyzed oxidation (MCO) at physiological temperature through laser light scattering, UV-vis, FTIR, and FESEM imaging. Light scattering data show a decrease in the hydrodynamic radius of elastin upon oxidation for the first hour. The rate of size reduction of ROS-treated elastin and the rate for self-assembly of bare elastin in the first two hours is found to be almost the same. However, the rate of association of ROS-treated is one order slower than the bare elastin after one hour. UV-vis absorption shows a blue shift accompanied by increased absorption, followed by a redshift and broadening of peak. FTIR data reveal changes in the secondary structures for both bare and oxidized elastin with time. While bare elastin coacervation increases unordered structure, the corresponding case of oxidized elastin saw a rise in β-sheet. FESEM images show the morphological changes occurring with time. Thus, we conclude that oxidative stress leads to structural rearrangement of the protein through interaction with the polar and hydrophobic domains, followed by aggregation. This study might be helpful for therapeutics focusing on preventing elastin degradation against aging.

Gene knockout of glutathione reductase results in increased sensitivity to heavy metals in Acidithiobacillus caldus

Acidithiobacillus caldus plays an important role in bioleaching of low-grade metal ore. It can promote the release of heavy metals in mining-associated habitats and survive in high concentrations of heavy metals. Functions of glutathione reductase (GR) in cell defense against reactive oxygen species caused by heavy metals have been elucidated in some eukaryotic cells and bacteria; however, no information is available in A. caldus. In this research, the methods of bioinformatics, gene expression, GR activity assays were used to detect and characterize the glutathione reductase gene from the A. caldus MTH-04 strain. Then, A. caldus gr knockout mutant and gr overexpression strain were constructed, and the heavy metal tolerant properties and transcriptional levels of ROS related genes of them were compared to study the function of GR. The results showed that, a putative gr gene F0726_RS04210 was detected in the genome of A. caldus MTH-04. The purified recombinant protein of F0726_RS04210 showed remarkable GR activity at optimal pH 7.0 and 30°C using in vitro assay. The evolutionary relationship of GR from A. caldus MTH-04 was close to that from Escherichia coli K12. Gene knockout or overexpression of gr in A. caldus did not affect the growth rate on S0 medium, suggesting that GR did not play a key role in the activation of sulfur. Deletion of gr resulted in increased sensitivity to heavy metals (Cu2+ and Zn2+) in A. caldus, and the gr overexpression strain showed enhanced tolerance to heavy metals. Furthermore, transcription analysis also revealed strong correlations between GR and the antioxidant pathway. The above results suggest that GR can play an important role in heavy metal tolerance in A. caldus.

Evaluation of UV-B protective properties of leaves and seeds of Achyranthes aspera in Asian catfish Clarias batrachus (Linn.)

The ultraviolet-B (UV-B) radiation is harmful to the aquatic organisms. The UV-B protective properties of leaves and seeds of herb Achyranthes aspera were evaluated in Clarias batrachus. Fish were fed with four diets-EFL1, EFL2 containing 0.25 and 0.5% leaves, EFS containing 0.5% seeds and control, CF. After 83 days of feeding, fish were exposed to UV-B (157 µW/cm²) for 7 days at the rate of 15 min/day. One batch of fish in each treatment was kept unexposed. Significantly higher final weight was found in EFS followed by EFL2 and EFL1 treatments. It was higher in unexposed fish compared to the exposed ones. Among exposed fish, significantly higher lysozyme was found in EFS and myeloperoxidase in EFS and EFL2 compared to others. Nitric oxide synthase and superoxide dismutase levels were significantly higher in liver and head kidney of EFS diet fed fish compared to others. Thiobarbituric acid reactive substances (TBARS) and carbonyl protein levels were minimum in EFS followed by EFL2. The independent sample t-test showed that nitric oxide synthase was significantly higher and myeloperoxidase and TBARS levels were significantly lower in unexposed group compared to the exposed fish in respective treatment. There were up-regulations of TNF-α, iNOS, NF-kB, BAX, Cytochrome c, SOD-c, Caspase 3, Caspase 9, BCL2 in liver and head kidney of leaves and seeds incorporated diets fed fish compared to control. Supplementation of A. aspera seeds and leaves at 0.5% level in diets gave UV-B protection to the fish.

Physicochemical and biological impact of metal-catalyzed oxidation of IgG1 monoclonal antibodies and antibody-drug conjugates via reactive oxygen species

Biotherapeutics are exposed to common transition metal ions such as Cu(II) and Fe(II) during manufacturing processes and storage. IgG1 biotherapeutics are vulnerable to reactive oxygen species (ROS) generated via the metal-catalyzed oxidation reactions. Exposure to these metal ions can lead to potential changes to structure and function, ultimately influencing efficacy, potency, and potential immunogenicity of the molecules. Here, we stress four biotherapeutics of the IgG1 subclass (trastuzumab, trastuzumab emtansine, anti-NaPi2b, and anti-NaPi2b-vc-MMAE) with two common pharmaceutically relevant metal-induced oxidizing systems, Cu(II)/ ascorbic acid and Fe(II)/ H₂O₂, and evaluated oxidation, size distribution, carbonylation, Fc effector functions, antibody-dependent cellular cytotoxicity (ADCC) activity, cell anti-proliferation and autophaghic flux. Our study demonstrates that the extent of oxidation was metal ion-dependent and site-specific, leading to decreased FcγRIIIa and FcRn receptor binding and subsequently potentially reduced bioactivity, though antigen binding was not affected to a great extent. In general, the monoclonal antibody (mAb) and corresponding antibody-drug conjugate (ADC) showed similar impacts to product quality when exposed to the same metal ion, either Cu(II) or Fe(II). Our study clearly demonstrates that transition metal ion binding to therapeutic IgG1 mAbs and ADCs is not random and that oxidation products show unique structural and functional ramifications. A critical outcome from this study is our highlighting of key process parameters, route of degradation, especially oxidation (metal catalyzed or via ROS), on the CH1 and Fc region of full-length mAbs and ADCs.

Abbreviations: DNPH 2,4-dinitrophenylhydrazine; ADC Antibody drug conjugate; ADCC Antibody-dependent cellular cytotoxicity; CDR Complementary determining region; DTT Dithiothreitol; HMWF high molecular weight form; LC-MS Liquid chromatography–mass spectrometry; LMWF low molecular weight forms; MOA Mechanism of action; MCO Metal-catalyzed oxidation; MetO Methionine sulfoxide; mAbs Monoclonal antibodies; MyBPC Myosin binding protein C; ROS Reactive oxygen species; SEC Size exclusion chromatography

Protein Oxidation in Muscle Foods: A Comprehensive Review

Muscle foods and their products are a fundamental part of the human diet. The high protein content found in muscle foods, as well as the high content of essential amino acids, provides an appropriate composition to complete the nutritional requirements of humans. However, due to their special composition, they are susceptible to oxidative degradation. In this sense, proteins are highly susceptible to oxidative reactions. However, in contrast to lipid oxidation, which has been studied in depth for decades, protein oxidation of muscle foods has been investigated much less. Moreover, these reactions have an important influence on the quality of muscle foods, from physico-chemical, techno-functional, and nutritional perspectives. In this regard, the loss of essential nutrients, the impairment of texture, water-holding capacity, color and flavor, and the formation of toxic substances are some of the direct consequences of protein oxidation. The loss of quality for muscle foods results in consumer rejection and substantial levels of economic losses, and thus the control of oxidative processes is of vital importance for the food industry. Nonetheless, the complexity of the reactions involved in protein oxidation and the many different factors that influence these reactions make the mechanisms of protein oxidation difficult to fully understand. Therefore, the present manuscript reviews the fundamental mechanisms of protein oxidation, the most important oxidative reactions, the main factors that influence protein oxidation, and the currently available analytical methods to quantify compounds derived from protein oxidation reactions. Finally, the main effects of protein oxidation on the quality of muscle foods, both from physico-chemical and nutritional points of view, are also discussed.

Copper oxide (CuO) and manganese oxide (MnO) nanoparticles induced biomass accumulation, antioxidants biosynthesis and abiotic elicitation of bioactive compounds in callus cultures of Ocimum basilicum (Thai basil)

Nano-elicitation is one among the prioritised strategies considered globally for sustainable and uniform production of industrially important medicinal compounds. Ocimum basilicum (Thai basil), a renowned medicinal species is a reservoir of commercially vital metabolites and proved for its health assuring effects in cancer, diabetes, microbial and cardiovascular diseases. However, its consumption and industrial demand raised intent to divert towards better alternates for ensuring sustainable production of medicinal compounds. Herein, we investigated the comparative potential of metal oxide [copper oxide (CuO) and manganese oxide (MnO)] nanoparticles to elicit the biosynthesis of bioactive metabolites and antioxidative capacity of O.basilicum callus cultures. Results showed that callus grown on MS media supplemented with 10 mg/L CuO-NPs resulted in the highest biomass accumulation (FW: 172.8 g/L, DW: 16.7 g/L), phenolic contents (TPC: 27.5 mg/g DW), and flavonoid contents (TFC: 9.1 mg/g DW) along with antioxidant activities (DPPH: 94%, ABTS: 881 μM TEAC, FRAP: 386 μM TEAC) compared with MnO-NPs and control. Likewise, the Superoxide dismutase (SOD: 1.28 nM/min/mg FW) and Peroxidase (POD: 0.48 nM/min/mg FW) activities were also recorded maximum in CuO-NPs elicited cultures than MnO-NPs and control. Moreover, the HPLC results showed that rosmarinic acid (11.4 mg/g DW), chicoric acid (16.6 mg/g DW), eugenol (0.21 mg/g DW) was found optimum in cultures at 10 mg/L CuO-NPs. Overall, it can be concluded that CuO nanoparticles can be effectively used as a elicitor for biosynthesis of metabolites in callus cultures of O. basilicum (Thai basil). The study is indeed a contribution to the field that will help decoding the mechanism of action of CuO NPs. However, further molecular investigations are needed to fully develop understanding about the metabolic potential of O. bascillicum and scalling up this protocol for bulkup production of bioactive compounds.

Altering Amino Acid Profile in Catharanthus Roseus (L.) G. Don Using Potassium and Ascorbic Acid Treatments

Background:

Catharanthus roseus (L.) G. Don is the main source of alkaloids anticancer drugs. Alkaloids are derived from amino acids and can lead to changes in these valuable compounds.

Objective:

This experiment evaluated the variation of amino acids under potassium and ascorbic acid treatments.

Methods:

Different concentrations (1.5, 3.16, 15 and 30 mM) and forms (K2SO4 and KNO3) of potassium (K+) were added to plants via Hoagland’s nutrient solution. Ascorbic acid (AsA) (750 mg L-1) was sprayed on the leaves surfaces on days 68 and 78. Amino acids were extracted from 90-day-old plant leaves, and different amino acids were determined by High-Performance Liquid Chromatography with fluorescence detection.

Results:

Amino acids increased in K+ deficiency (1.5 mM), but changes in negatively charged amino acids were lower. In contrast, N-rich amino acids showed the biggest change. In excessive K+, branched-chain and aromatic amino acids decreased, while the least amount of the other amino acids was observed in the plants treated with optimum K+.

Conclusion:

The exterior of AsA and excessive K+ cause branched-chain and aromatic amino acids, aspartic acid and glutamic acid to decrease.

An in vitro assay of the effect of lysine oxidation end-product, α-aminoadipic acid, on the redox status and gene expression in probiotic Lactobacillus reuteri PL503

This study was designed to gain information about the underlying mechanisms of the effects of a food-occurring free oxidized amino acid, α-aminoadipic acid (AAA), on the probiotic Lactobacillus reuteri PL503. This bacterium was incubated in colonic-simulated conditions (37 °C for 24 h in microaerophilic conditions) and exposed to three food-compatible AAA concentrations, namely, 1 mM, 5 mM, and 10 mM. A control group with no AAA exposure was also considered. Each of the four experimental conditions was replicated three times and samplings were collected at 12, 16, 20, and 24 h. The downregulation of the uspA gene by AAA (0.5-fold decrease as compared to control) suggests that AAA is identified as a potential chemical threat. The dhaT gene, implicated in the antioxidant defense, was found to be upregulated in bacteria treated with 1 and 5 mM AAA (up to twofold increase, as compared to control), which suggest the ability of the oxidized amino acid to impair the redox status of the bacterium. In fact, AAA caused an increased production of reactive oxygen species (ROS) and the accretion of post-translational changes (protein carbonylation) in L. reuteri (up to 13 nmol allysine/mg protein vs 1.8 nmol allysine/mg protein in control). These results suggest that probiotic bacteria identify oxidized amino acids as harmful species and activate mechanisms that may protect themselves and the host against their noxious effects.

Self-Immolative Dye-Doped Polymeric Probe for Precisely Imaging Hydroxyl Radicals by Avoiding Leakage

For sensing low abundance of biomarkers, utilizing nanocarriers to load dyes is an efficient method to amplify the detected signal. However, the non-specific leak of the internal dyes in this approach is accompanied by false positive signals, resulting in inaccurate signal acquirement. To address this issue, in this work, we reported a novel signal amplification strategy with dye as a scaffold to construct a self-immolative dye-doped polymeric probe (SDPP). In our proposed approach, the dyes were covalently integrated into the main chain of a polymer, which can avoid the non-specific leak of the dye when used in a rigorous biological environment, thus evading the false positive signal. As a prototype of this concept, a SDPP, which responds to hydroxyl radicals (^•OH), was rationally fabricated. Upon being activated by ^•OH, SDPP will liberate the dye through a self-immolative reaction to bind with protein for amplifying the fluorescence signal. Compared with a dye-loaded nanoprobe, SDPP can precisely track intracellular basal ^•OH levels and visualize the ^•OH associated with myocarditis in vivo. More importantly, the attempt in this work not only provides an effective molecular tool to investigate the role of ^•OH in cardiopathy, but also puts forward a new direction to current signal-amplifying strategies for precisely and reliably acquiring the intracellular molecular information.

A Fungal Secretome Adapted for Stress Enabled a Radical Wood Decay Mechanism

Brown rot fungi release massive amounts of carbon from forest deadwood, particularly at high latitudes. These fungi degrade wood by generating small reactive oxygen species (ROS) to loosen lignocellulose, to then selectively remove carbohydrates. The ROS mechanism has long been considered the key adaptation defining brown rot wood decomposition, but recently, we found preliminary evidence that fungal glycoside hydrolases (GHs) implicated in early cell wall loosening might have been adapted to tolerate ROS stress and to synergize with ROS to loosen woody lignocellulose. In the current study, we found more specifically that side chain hemicellulases that help in the early deconstruction of the lignocellulosic complex are significantly more tolerant of ROS in the brown rot fungus Rhodonia placenta than in a white rot fungus (Trametes versicolor) and a soft rot fungus (Trichoderma reesei). Using proteomics to understand the extent of tolerance, we found that significant oxidation of secreted R. placenta proteins exposed to ROS was less than half of the oxidation observed for T. versicolor or T. reesei. The principal oxidative modifications observed in all cases were monooxidation and dioxidation/trioxidation (mainly in methionine and tryptophan residues), some of which were critical for enzyme activity. At the peptide level, we found that GHs in R. placenta were the least ROS affected among our tested fungi. These results confirm and describe underlying mechanisms of tolerance in early-secreted brown rot fungal hemicellulases. These enzymatic adaptations may have been as important as nonenzymatic ROS pathway adaptations in brown rot fungal evolution.

Ecotoxicological evaluation of water from the Sorocaba River using an integrated analysis of biochemical and morphological biomarkers in bullfrog tadpoles, Lithobates catesbeianus ()

Lithobates catesbeianus tadpoles were exposed for 96 h to water from two sites of the Sorocaba River (summer and winter), Ibiúna (PI) and Itupararanga reservoir (PIR) that contained metals. In the liver, in PI, the glutathione peroxidase (GPx) decreased, and the glutathione S-transferase (GST) and carbonyl proteins (PCO) increased. In PIR, the glutathione reduced (GSH) increased, while there was a decrease in catalase (CAT), GPx, GST, PCO, and superoxide dismutase (SOD). In winter, GPx and GST increased in both points. Regarding the kidneys, lipoperoxidation (LPO) levels and GST decreased, while GSH increased in the summer. In the winter, LPO increased in PI. In the muscle, in the summer, there was an increase in GSH and GST and change in PCO. In the winter, the levels of PCO increased and CAT decreased in PIR. The area and volume of the hepatocyte and nucleus area increased in the summer and decreased in the winter. Hepatic melanin decreased in the summer after exposure to PIR water. There were the systemic effects of Sorocaba River water exposure at different times of the year with alterations in biomarkers at different levels, in which kidney shows highest Integrated Response of Biomarkers (IBR) value followed by liver and muscle. Biochemical biomarkers were more sensitive than morphological ones. The more sensitive biochemical markers were MT, PCO, GST and LPO. These effects confirm the hypothesis of metabolic alteration in bullfrog tadpoles by the Sorocaba River water.

Medium nitrogen optimized Boehmeria nivea L. growth in copper contaminated soil

Copper (Cu) pollution in agricultural soils is considered as a serious health risk due to its accumulation in plants. Thus, there is an urgent need to optimize nutrient application for higher yield with lower Cu uptake to ensure food security. A pot experiment was conducted to investigate the effectiveness of nitrogen fertilizer (N) on Boehmeria nivea growth, gas exchange characteristics, antioxidant capacity and uptake of Cu in contaminated soil. Therefore, combinations of Cu levels (0, 100, 300 mg kg^-1) and N levels (0, 140, 280, 420 kg ha^-1) were applied. The results showed that N at 280 kg ha^-1 significantly (≤0.05) increased plant growth in terms of fresh biomass, plant height, stem diameter and number of leaves per plant up to100 mg kg^-1 Cu in soil for all harvests (H₁, H₂, H₃ and H₄). However, the interactive effect of Cu and N on Cu uptake by plant varied among N levels. Furthermore, N at 280 kg ha^-1 also improved the gas exchange characteristics viz., net photosynthesis (Pn), transpiration rate (Tr) and stomatal conductance (gs), while decreased oxidative stress in B. nivea up to 100 mg kg^-1 Cu in soil, relative to control. Thus N at 280 kg ha^-1 can be considered as an effective dose for high fresh biomass with lower Cu uptake by B. nivea grown as fodder in Cu contaminated soils (≤100 mg kg^-1). Overall, present research highlighted the necessity of balanced or optimum N application for sustainable B. nivea forage production in Cu contaminated agricultural lands.

Irrigation water of different sources affects fruit quality attributes and heavy metals contents of un-grafted and commercial mango cultivars

In peri-urban areas, waste water is used to irrigate orchards due to scarcity of fresh water which increases heavy metals contents in soils, leaves and fruits. Due to excessive waste water irrigations, heavy metals enter into the food chain, which eventually causes metabolic disorders in humans. The present study was envisaged to investigate the effects of canal, tubewell and sewage water on the quality of mango fruits and heavy metals accumulation in soils, leaves and fruits. Leaf and fruit samples from an un-grafted (Desi mango) and six commercial cultivars of mango (Anwar Rataul, Aman Dusehri, Sufaid Chaunsa, Samar Bahisht Chaunsa, Kala Chaunsa and Anwar Rataul Late) grafted on Desi mango were collected from different mango orchards located in peri-urban areas of Multan (Pakistan) and analyzed for some physico-chemical attributes and heavy metals contents. Soil samples were also taken from these orchards irrigated with different water sources to assess the soils' heavy metals status. A significant variation was observed among the mango cultivars for their physico-chemical attributes. Sewage water irrigation improved total soluble solids (TSS), titratable acidity, ascorbic acid content, total phenolics, total carotenoids, total flavonoids and antioxidant activity of mango fruits. However, it did not affect fruit weight and shelf life. Among the heavy metals, copper and nickel contents were found in greater amounts in soils, leaves and fruits of sewage water irrigated orchards than canal and tubewell water irrigated ones. However, zinc and cadmium were not detected in any soil, water, leaf or fruit sample. The interaction among the sources of irrigation and the mango cultivars was significant for copper accumulation in different soil layers, copper and nickel accumulation in leaves of different mango cultivars, and fruit weight, titratable acidity, ascorbic acid content, total flavonoids and shelf life of mango fruits.

Effects of oxidative modification of peroxyl radicals on the structure and foamability of chickpea protein isolates

A chickpea protein isolate (CPI) was oxidized using peroxyl radicals derived from 2,2'-azobis (2-amidopropane) dihydrochloride (AAPH), and the structural and foaming properties of the oxidized CPI were evaluated. The oxidation degree of protein was determined by measuring carbonyl content, dimer tyrosine content, free thiol content, and total thiol content. The structural changes of oxidized protein were evaluated by surface hydrophobicity, endogenous fluorescence intensity, Fourier transform infrared spectroscopy, SDS-PAGE, and amino acid content changes. Compared with the control group (0 mmol/L AAPH), moderate oxidation (0.04 mmol/L AAPH) led to the formation of a soluble protein with flexibility, which could improve the foaming properties of the protein (foaming capacity and stability increased by 25.50% and 6.38%, respectively). Over-oxidized (25 mmol/L AAPH) protein exhibited improved foaming capability, but its foam stability was reduced owing to the formation of insoluble aggregates. The results indicate that oxidation can change protein conformation, and the protein structure can affect the foamability of the CPI. PRACTICAL APPLICATION: CPI is a protein supplement food. Protein oxidation can occur during processing and storage, thereby affecting protein function. In this study, we evaluated how peroxy free radicals affect the structure, solubility and foaming properties of CPI, and clarified the mechanism between them. It has been found that peroxy free radicals can accelerate the oxidation of proteins and have a significant effect on foaming. Therefore, the degree of oxidation should be controlled to improve the quality of CPI.

A conserved, buried cysteine near the P-site is accessible to cysteine modifications and increases ROS stability in the P-type plasma membrane H+-ATPase

Sulfur-containing amino acid residues function in antioxidative responses, which can be induced by the reactive oxygen species generated by excessive copper and hydrogen peroxide. In all Na+/K+, Ca2+, and H+ pumping P-type ATPases, a cysteine residue is present two residues upstream of the essential aspartate residue, which is obligatorily phosphorylated in each catalytic cycle. Despite its conservation, the function of this cysteine residue was hitherto unknown. In this study, we analyzed the function of the corresponding cysteine residue (Cys-327) in the autoinhibited plasma membrane H+-ATPase isoform 2 (AHA2) from Arabidopsis thaliana by mutagenesis and heterologous expression in a yeast host. Enzyme kinetics of alanine, serine, and leucine substitutions were identical with those of the wild-type pump but the sensitivity of the mutant pumps was increased towards copper and hydrogen peroxide. Peptide identification and sequencing by mass spectrometry demonstrated that Cys-327 was prone to oxidation. These data suggest that Cys-327 functions as a protective residue in the plasma membrane H+-ATPase, and possibly in other P-type ATPases as well.

Oxidative, Reductive, and Nitrosative Stress Effects on Epigenetics and on Posttranslational Modification of Enzymes in Cardiometabolic Diseases

Oxidative (OS), reductive (RS), and nitrosative (NSS) stresses produce carbonylation, glycation, glutathionylation, sulfhydration, nitration, and nitrosylation reactions. OS, RS, and NSS are interrelated since RS results from an overactivation of antioxidant systems and NSS is the result of the overactivation of the oxidation of nitric oxide (NO). Here, we discuss the general characteristics of the three types of stress and the way by which the reactions they induce (a) damage the DNA structure causing strand breaks or inducing the formation of 8-oxo-d guanosine; (b) modify histones; (c) modify the activities of the enzymes that determine the establishment of epigenetic cues such as DNA methyl transferases, histone methyl transferases, acetyltransferases, and deacetylases; (d) alter DNA reparation enzymes by posttranslational mechanisms; and (e) regulate the activities of intracellular enzymes participating in metabolic reactions and in signaling pathways through posttranslational modifications. Furthermore, the three types of stress may establish new epigenetic marks through these reactions. The development of cardiometabolic disorders in adult life may be programed since early stages of development by epigenetic cues which may be established or modified by OS, RS, and NSS. Therefore, the three types of stress participate importantly in mediating the impact of the early life environment on later health and heritability. Here, we discuss their impact on cardiometabolic diseases. The epigenetic modifications induced by these stresses depend on union and release of chemical residues on a DNA sequence and/or on amino acid residues in proteins, and therefore, they are reversible and potentially treatable.

Attenuation of Oxidative Stress by Cannabinoids and Cannabis Extracts in Differentiated Neuronal Cells

In this proof-of-concept study, the antioxidant activity of phytocannabinoids, namely cannabidiol (CBD) and Δ9- tetrahydrocannabinol (THC), were investigated using an in vitro system of differentiated human neuronal SY-SH5Y cells. The oxidative stress was induced by hydrogen peroxide, as reactive oxygen species (ROS). Alzheimer's disease (AD)-like pathological conditions were mimicked in vitro by treating the differentiated neuronal cells with amyloid-β_1-42 (Aβ_1-42) in the presence of Cu(II). We showed that THC had a high potency to combat oxidative stress in both in vitro models, while CBD did not show a remarkable antioxidant activity. The cannabis extracts also exhibited a significant antioxidant activity, which depended on the ratio of the THC and CBD. However, our results did not suggest any antagonist effect of the CBD on the antioxidant activity of THC. The effect of cannabis extracts on the cell viability of differentiated human neuronal SY-SH5Y cells was also investigated, which emphasized the differences between the bioactivity of cannabis extracts due to their composition. Our preliminary results demonstrated that cannabis extracts and phytocannabinoids have a promising potential as antioxidants, which can be further investigated to develop novel pharmaceuticals targeting oxidative stress therapy.

Deficiency of Grx1 leads to high sensitivity of HeLaS3 cells to oxidative stress via excessive accumulation of intracellular oxidants including ROS

Oxidative stress is often initiated by excess reactive oxygen species (ROS) production, resulting in macromolecular damage, which is implicated in many disease states. Glutaredoxin 1 (Grx1) is an antioxidant enzyme that plays an important role in redox signaling and redox homeostasis. In the present study, we generated HeLaS3 cell lines deficient in Grx1 by the CRISPR/CAS9 system to clarify how Grx1 affects the physiological activities of HeLaS3 cells to respond to oxidative stress. First, the survival assay revealed that Grx1-deficient HeLaS3 cells were more sensitive to γ-ray irradiation, heat shock and H₂O₂ exposure than HeLaS3 wild-type cells. Next, the intracellular redox state was investigated using a fluorescent probe (2'-7'dichlorofluorescin diacetate), and the oxidized state of total proteins and a peroxidase Prx2 were measured by Western blot analysis. Exposure to γ-ray irradiation, heat shock and H₂O₂ significantly induced more accumulation of intracellular oxidants including ROS and higher levels of oxidized proteins in Grx1-deficient HeLaS3 cells. Furthermore, MitoSox Red staining demonstrated that Grx1 deficiency causes a higher level of oxidants production in mitochondria. Moreover, Grx1-deficient HeLaS3 cells had a higher cytochrome c level and higher apoptosis rate (Annexin-V/FITC and EthD-III staining assay) upon oxidative stress. These results suggested that Grx1 deficiency lead to mitochondrial redox homeostasis disruption and apoptotic cell death upon oxidative stress. In addition, the results of proliferation assay and MitoTracker staining assay (multinuclear cell formation rate) suggested that oxidative stress exposure inhibits cell proliferation maybe by affecting cytoplasmic division in Grx1-deficient HeLaS3 cells.

Importance of the Use of Oxidative Stress Biomarkers and Inflammatory Profile in Aqueous and Vitreous Humor in Diabetic Retinopathy

Diabetic retinopathy is one of the leading causes of visual impairment and morbidity worldwide, being the number one cause of blindness in people between 27 and 75 years old. It is estimated that ~191 million people will be diagnosed with this microvascular complication by 2030. Its pathogenesis is due to alterations in the retinal microvasculature as a result of a high concentration of glucose in the blood for a long time which generates numerous molecular changes like oxidative stress. Therefore, this narrative review aims to approach various biomarkers associated with the development of diabetic retinopathy. Focusing on the molecules showing promise as detection tools, among them we consider markers of oxidative stress (TAC, LPO, MDA, 4-HNE, SOD, GPx, and catalase), inflammation (IL-6, IL-1ß, IL-8, IL-10, IL-17A, TNF-α, and MMPs), apoptosis (NF-kB, cyt-c, and caspases), and recently those that have to do with epigenetic modifications, their measurement in different biological matrices obtained from the eye, including importance, obtaining process, handling, and storage of these matrices in order to have the ability to detect the disease in its early stages.

Carbonylation of proteins-an element of plant ageing

Carbonylation-ROS-dependent posttranslational modification of proteins-may be regarded as one of the important events in the process of ageing or senescence in plants. Ageing is the progressive process starting from seed development (plants) and birth (animals). The life-span of living organisms depends on many factors and stresses, which influence reactive oxygen species (ROS) level. The imbalance of their production and scavenging causes pathophysiological conditions that accelerate ageing. ROS modify nucleic acids, lipids, sugars and proteins. The level of carbonylated proteins can serve as an indicator of an oxidative cellular status. Several pathways of protein carbonylation, e.g. the conjugation with reactive carbonyl species, and/or a direct metal-catalysed oxidative attack on amino acids residues are known. Dysfunctional carbonylated proteins are more prone to degradation or form aggregates when the proteolytic machinery is inhibited, as observed in ageing. Protein carbonylation may contribute to formation of organelle-specific signal and to the control of protein quality. Carbonylated proteins are formed during the whole plant life; nevertheless, accelerated ageing stimulates the accumulation of carbonyl derivatives. In the medicine-related literature, concerned ageing and ROS-mediated protein modifications, this topic is extensively analysed, in comparison to the plant science. In plant science, ageing and senescence are considered to describe slightly different processes (physiological events). However, senescence (Latin: senēscere) means "to grow old". This review describes the correlation of protein carbonylation level to ageing or/and senescence in plants. Comparing data from the area of plant and animal research, it is assumed that some basic mechanism of time-dependent alterations in the cellular biochemical processes are common and the protein carbonylation is one of the important causes of ageing.

Effects of Biogenic Zinc Oxide Nanoparticles on Growth and Oxidative Stress Response in Flax Seedlings vs. In Vitro Cultures: A Comparative Analysis

Linum usitatissimum biosynthesizes lignans and neolignans that are diet and medicinally valuable metabolites. In recent years, zinc oxide nanoparticles (ZnONPs) have emerged as potential elicitors for the enhanced biosynthesis of commercial secondary metabolites. Herein, we investigated the influence of biogenic ZnONPs on both seedlings and stem-derived callus of L. usitatissimum. Seedlings of L. usitatissimum grown on Murashige and Skoog (MS) medium supplemented with ZnONPs (1-1000 mg/L) presented the highest antioxidant activity, total phenolic content, total flavonoid content, peroxidase and superoxide dismutase activities at 500 mg/L, while the maximum plantlet length was achieved with 10 mg/L. Likewise, the high-performance liquid chromatography (HPLC) analysis revealed the enhanced production of secoisolariciresinol diglucoside, lariciresinol diglucoside, dehydrodiconiferyl alcohol glucoside and guaiacylglycerol-β-coniferyl alcohol ether glucoside in the plantlets grown on the 500 mg/L ZnONPs. On the other hand, the stem explants were cultured on MS media comprising 1-naphthaleneacetic acid (1 mg/L) and ZnONPs (1-50 mg/L). The highest antioxidant and other activities with an enhanced rooting effect were noted in 25 mg/L ZnONP-treated callus. Similarly, the maximum metabolites were also accumulated in 25 mg/L ZnONP-treated callus. In both systems, the dose-dependent production of reactive oxygen species (ROS) was recorded, resulting in oxidative damage with a more pronounced toxic effect on in vitro cultures. Altogether, the results from this study constitute a first comprehensive view of the impact of ZnONPs on the oxidative stress and antioxidant responses in seedlings vs. in vitro cultures.

Common mechanisms activated in the tissues of aquatic and terrestrial animal models after TiO2 nanoparticles exposure

Titanium dioxide nanoparticles (TiO₂-NPs) are among the most popular manufactured and widely used nanoparticles. They are released into the environment, affecting terrestrial and aquatic ecosystems, with unexpected consequences to organisms and human health. The present study investigates the mediated toxicity imposed to the freshwater fish species, zebrafish (Danio rerio) and the prussian carp (Carassius gibelio), and to the terrestrial land snail Cornu aspersum, after their exposure to sublethal concentrations of TiO₂-NPs. Oxidative, proteolytic, genotoxic and apoptotic parameters in fish liver and gills, as well as on snail hemocytes were studied and the swimming performance was estimated in order to (a) estimate and suggest the most susceptible animal, and (b) propose a common battery of biomarkers as the most suitable indicator for biomonitoring studies against TiO₂-NPs. Our in vivo experiments demonstrated that NPs induced detrimental effects on animal physiology and swimming behavior, while no general pattern was observed in species and tissues responsiveness. Generally, TiO₂-NPs seemed to activate a group of molecules that are common for aquatic as well as terrestrial animals, implying the existence of a conserved mechanism. It seems that after exposure to TiO₂-NPs, a common mechanism is activated that involves the stimulation of immune system with the production of ROS, damage of lysosomal membrane, protein carbonylation, lipid peroxidation, DNA damage, following proteolysis by ubiquitin and finally apoptosis. Thus, the simultaneous use of the latter biomarkers could be suggested as a reliable multi parameter approach for biomonitoring of aquatic and terrestrial ecosystems against TiO₂-NPs.

Iron overload: Effects on cellular biochemistry

Iron is an essential element for human life. However, it is a pro-oxidant agent capable of reacting with hydrogen peroxide. An iron overload can cause cellular changes, such as damage to the plasma membrane leading to cell death. Effects of iron overload in cellular biochemical processes include modulating membrane enzymes, such as the Na, K-ATPase, impairing the ionic transport and inducing irreversible damage to cellular homeostasis. To avoid such damage, cells have an antioxidant system that acts in an integrated manner to prevent oxidative stress. In addition, the cells contain proteins responsible for iron transport and storage, preventing its reaction with other substances during absorption. Moreover, iron is associated with cellular events coordinated by iron-responsive proteins (IRPs) that regulate several cellular functions, including a process of cell death called ferroptosis. This review will address the biochemical aspects of iron overload at the cellular level and its effects on important cellular structures.

Antioxidant System and Biomolecules Alteration in Pisum sativum under Heavy Metal Stress and Possible Alleviation by 5-Aminolevulinic Acid

Environmental pollution is the most serious problem that affects crop productivity worldwide. Pisum sativum is a leguminous plant that is cultivated on a large scale in the Nile Delta of Egypt as a winter crop, and many of the cultivated fields irrigated with drainage water that contained many pollutants including heavy metals. The present research aimed to investigate the impact of Cd and Ni on the biochemical and physiological processes in P. sativum and evaluate the potential alleviation of their toxicity by 5-aminolevulinic acid (ALA). Seedlings of P. sativum were grown in Hoagland solution treated with CdCl2 or NiCl2 for 72 h in the growth chamber. Hydrogen peroxide, lipid peroxidation, protein carbonylation, reduced glutathione, oxidized glutathione, proline, phenolics, antioxidant enzymes, as well as Cd and Ni concentrations were measured at 0, 12, 24, 36, 48, 72 h. An experiment of alleviation was conducted where ALA was added to the growth solution at a concentration of 200 µM coupled with 100 µM of either CdCl2 or NiCl2. Hydrogen peroxide, lipid peroxidation, protein carbonylation, reduced glutathione, oxidized glutathione, proline, and phenolics were induced due to the toxicity of Cd and Ni. The activities of antioxidant enzymes [NADH-oxidase (EC: 1.6.3.1), ascorbate peroxidase (EC: 1.11.1.11), glutathione reductase (EC: 1.6.4.2), superoxide dismutase (EC: 1.15.1.1), and catalase (EC: 1.11.1.6)] were induced under the treatments of both metals. On the other hand, the soluble protein decreased gradually depending upon the time of exposure to the heavy metals. The concentration of Cd and Ni in the leaves treated plants increased in time of exposure dependent manner, while their contents remained within the acceptable limits. The addition of ALA decreased the oxidative stress in treated P. sativum plants. The results revealed the significance of using ALA in the cultivation of P. sativum might improve its tolerance against heavy metal stress.

Rapid global characterization of immunoglobulin G1 following oxidative stress

Although peroxide and leachable metal-induced chemical modifications are among the most important quality attributes in bioprocess development, there is no mainstream characterization method covering all common modifications theoretically possible on therapeutic proteins that also gives consistent results quickly. Here, we describe a method for rapid and consistent global characterization of leachable metals- or peroxide-stressed immunoglobulin (Ig) G1 monoclonal antibodies (mAbs). Using two independent protease digestions, data-independent acquisition and data-dependent acquisition liquid chromatography high-resolution mass spectrometry, we monitored 55 potential chemical modifications on trastuzumab, a humanized IgG1 mAb. Processing templates including all observed peptides were developed on Skyline to consistently monitor all modifications throughout the stress conditions for both enzymatic digestions. The Global Characterization Data Processing Site, a universal automated data processing application, was created to batch process data, plot modification trends for peptides, generate sortable and downloadable modification tables, and produce Jmol code for three-dimensional structural models of the analyzed protein. In total, 53 sites on the mAb were found to be modified. Oxidation rates generally increased with the peroxide concentration, while leachable metals alone resulted in lower rates of modifications but more oxidative degradants. Multiple chemical modifications were found on IgG1 surfaces known to interact with FcɣRIII, complement protein C1q, and FcRn, potentially affecting activity. The combination of Skyline templates and the Global Characterization Data Processing Site results in a universally applicable assay allowing users to batch process numerous modifications. Applying this new method to stability studies will promote a broader and deeper understanding of stress modifications on therapeutic proteins.

Oxidative Modification of Trichocyte Keratins

Oxidation of keratin results in a range of deleterious effects, including discolouration and compromised physical and mechanical properties. Keratin oxidative degradation is driven by molecular-level events, with accumulation of modifications at the protein primary level resulting directly in changes to secondary, tertiary and quaternary structure, as well as eventually changes in the observable physical and chemical properties. Advances in proteomic analysis techniques provide an increasingly clearer insight into the cascade of molecular modification underpinning keratin oxidation and how this translates through to higher order changes in properties. This chapter summarises the effects of oxidation on keratin-based materials, the types of molecular modification associated with this, and advances in techniques and approaches for characterising this modification.

Molecular Mechanism of Aniline Induced Spleen Toxicity and Neuron Toxicity in Experimental Rat Exposure: A Review

Aniline exposure leads to neuron and spleen toxicity specifically and makes diverse neurological effects and sar-coma that is defined by splenomegaly, hyperplasia, and fibrosis and tumors formation at the end. However, the molecular mechanism(s) of aniline-induced spleen toxicity is not understood well, previous studies have represented that aniline expo-sure results in iron overload and initiation of oxidative/nitrosative disorder stress and oxidative damage to proteins, lipids and DNA subsequently, in the spleen. Elevated expression of cyclins, cyclin-dependent kinases (CDKs) and phosphorylation of pRB protein along with increases in A, B and CDK1 as a cell cycle regulatory proteins cyclins, and reduce in CDK inhibitors (p21 and p27) could be critical in cell cycle regulation, which contributes to tumorigenic response after aniline exposure. Aniline-induced splenic toxicity is corre-lated to oxidative DNA damage and initiation of DNA glycosylases expression (OGG1, NEIL1/2, NTH1, APE1 and PNK) for removal of oxidative DNA lesions in rat. Oxidative stress causes transcriptional up-regulation of fibrogenic/inflammatory factors (cytokines, IL-1, IL-6 and TNF-α) via induction of nuclear factor-kappa B, AP-1 and redox-sensitive transcription factors, in aniline treated-rats. The upstream signalling events as phosphorylation of IκB kinases (IKKα and IKKβ) and mito-gen-activated protein kinases (MAPKs) could potentially be the causes of activation of NF-κB and AP-1. All of these events could initiate a fibrogenic and/or tumorigenic response in the spleen. The spleen toxicity of aniline is studied more and the different mechanisms are suggested. This review summarizes those events following aniline exposure that induce spleen tox-icity and neurotoxicity.

Disulfiram (Antabuse) Activates ROS-Dependent ER Stress and Apoptosis in Oral Cavity Squamous Cell Carcinoma

A paucity of advances in the development of novel therapeutic agents for squamous cell carcinomas of the head and neck, oral cavity (OSCC) and oropharynx, has stagnated disease free survival rates over the past two decades. Although immunotherapies targeted against checkpoint inhibitors such as PD-1 or CTLA-4 are just now entering the clinic for late stage disease with regularity the median improvement in overall survival is only about three months. There is an urgent unmet clinical need to identify new therapies that can be used alone or in combination with current approaches to increase survival by more than a few months. Activation of the apoptotic arm of the unfolded response (UPR) with small molecules and natural products has recently been demonstrated to be a productive approach in pre-clinical models of OSCC and several other cancers. The aim of current study was to perform a high throughput screen (HTS) with a diverse chemical library to identify compounds that could induce CHOP, a component of the apoptotic arm of the UPR. Disulfiram (DSF, also known as Antabuse) the well-known aversion therapy used to treat chronic alcoholism emerged as a hit that could generate reactive oxygen species, activate the UPR and apoptosis and reduce proliferation in OSCC cell cultures and xenografts. A panel of murine embryonic fibroblasts null for key UPR intermediates (e.g., Chop and Atf4) was resistant to DSF suggesting that an intact UPR is a key element of the mechanism regulating the antiproliferative effects of DSF.

Negative Impacts of Biochars on Urease Activity: High pH, Heavy Metals, Polycyclic Aromatic Hydrocarbons, or Free Radicals?

Although biochars show promise for soil remediation, their negative impacts have not been systematically assessed. This study investigated the effects of corn cob biochars on urease-mediated urea hydrolysis and attempted to determine the mechanisms underlying those effects. The results showed that biochars inhibited urease activity (indicated by the NH₄⁺ generation). Released heavy metals and polyaromatic hydrocarbons explained the 20% inhibition of urease activity in biochar supernatants (200 °C) but could not explain the 70% inhibition in particle systems (400 °C). The levels of protein carbonyl and nitrotyrosine, common oxidative damagers of urease, were high in particle systems but very low in biochar supernatants. The electron paramagnetic resonance signal intensity reached its highest level in the 400 °C biochar and decreased in the 500 °C biochar, possibly due to the decomposition of organic molecules. The observed inhibition of urease activity may be the result of oxidative reactions with free radicals on the biochar surface or oxidative reactions with reactive oxygen species promoted by free radicals. We suggest that these potential hazards be evaluated further to gauge the relevance of these findings to field conditions and to assist in the development of safe and sustainable application schemes for biochars.

Crystal structures of manganese-dependent transcriptional repressor MntR (Rv2788) from Mycobacterium tuberculosis in apo and manganese bound forms

The pathogenic Mycobacterium tuberculosis encodes two members of the DtxR family metalloregulators, IdeR and MntR. IdeR represses gene expression in response to ferrous iron, while MntR (Rv2788) functions as a manganese-dependent transcriptional repressor, which represses the expression of manganese transporter genes to maintain manganese homeostasis. Although the structural study towards IdeR is in-depth, there is no MntR structure available. Herein, we report both apo and manganese bound forms of MntR structures from M. tuberculosis. MntR has evolved into two metal ion binding sites like other DtxR proteins and for the first time, we captured the two sites fully occupied by its natural ions with one Mn²⁺ ion at the first site and two Mn²⁺ ions at the second binding site (binuclear manganese cluster). The conformation change of MntR resulting from manganese binding could prime the MntR for DNA binding, which is a conserved activation mechanism among DtxR family.

Oxidative damage and antioxidant defense are assay and tissue-dependent both in captive and wild-caught bank voles (Myodes glareolus) before and after reproduction

Reproduction is costly and life-history theory predicts that current parental investment will result in lower survival or decreased future reproduction. The physiological mechanisms mediating the link between reproduction and survival are still under debate and elevated oxidative damage during reproduction has been proposed as a plausible candidate. Previous studies of oxidative stress during reproduction in animals under natural conditions have been restricted to analyses of blood. Herein, we measured the level of oxidative damage to lipids (tiobarbituric-acid-reactive substances) and proteins (carbonyls) in the liver, kidneys, heart and skeletal muscles in free-living bank vole females from spring and autumn generations, before and after reproduction. Antioxidant defense in the liver and kidneys was also determined. We expected oxidative damage to tissues and hypothesized that the damage would be more uniform between tissues in wild animals compared to those breeding under laboratory conditions. Considering all combinations of markers/tissues/generations, oxidative damage in females did not differ before and after reproduction in 12 comparisons, was lower after reproduction in three comparisons, and was higher after breeding in one comparison. The total glutathione was significantly increased after reproduction only in the liver of the autumn generation and there was no change in catalase activity. Our results confirm-for the first time in the field-previous observations from laboratory studies that there is no simple link between oxidative stress and reproduction and that patterns depend on the tissue and marker being studied. Overall, however, our study does not support the hypothesis that the cost of reproduction in bank voles is mediated by oxidative stress in these tissues.

Early events in copper-ion catalyzed oxidation of α-synuclein

Previous studies on metal-ion catalyzed oxidation of α-synuclein oxidation have mostly used conditions that result in extensive modification precluding an understanding of the early events in this process. In this study, we have examined time-dependent oxidative events related to α-synuclein modification using six different molar ratios of Cu²⁺/H₂O₂/protein and Cu²⁺/H₂O₂/ascorbate/protein resulting in mild to moderate extents of oxidation. For a Cu²⁺/H₂O₂/protein molar ratio of 2.3:7.8:1 only low levels of carbonyls were detected (0.078 carbonyls per protein), whereas a molar ratio of 4.7:15.6:1 gave 0.22 carbonyls per α-synuclein within 15 min. With the latter conditions, rapid conversion of 3 out of 4 methionines (Met) to methionine sulfoxide, and 2 out of 4 tyrosines (Tyr) were converted to products including inter- and intra-molecular dityrosine cross-links and protein oligomers, as determined by SDS-PAGE and Western blot analysis. Limited histidine (His) modification was observed. The rapid formation of dityrosine cross-links was confirmed by fluorescence and mass-spectrometry. These data indicate that Met and Tyr oxidation are early events in Cu²⁺/H₂O₂-mediated damage, with carbonyl formation being a minor process. With the Cu²⁺/H₂O₂/ascorbate system, rapid protein carbonyl formation was detected with the first 5 min, but after this time point, little additional carbonyl formation was detected. With this system, lower levels of Met and Tyr oxidation were detected (2 Met and 1 Tyr modified with a Cu²⁺/H₂O₂/ascorbate/protein ratio of 2.3:7.8:7.8:1), but greater His oxidation. Only low levels of intra- dityrosine cross-links and no inter- dityrosine oligomers were detected under these conditions, suggesting that ascorbate limits Cu²⁺/H₂O₂-induced α-synuclein modification.

Iron overload impact on P-ATPases

Iron is a chemical element that is active in the fundamental physiological processes for human life, but its burden can be toxic to the body, mainly because of the stimulation of membrane lipid peroxidation. For this reason, the action of iron on many ATPases has been studied, especially on P-ATPases, such as the Na⁺,K⁺-ATPase and the Ca²⁺-ATPase. On the Fe²⁺-ATPase activity, the free iron acts as an activator, decreasing the intracellular Fe²⁺ and playing a protection role for the cell. On the Ca²⁺-ATPase activity, the iron overload decreases the enzyme activity, raising the cytoplasmic Ca²⁺ and decreasing the sarco/endoplasmic reticulum and the Golgi apparatus Ca²⁺ concentrations, which could promote an enzyme oxidation, nitration, and fragmentation. However, the iron overload effect on the Na⁺,K⁺-ATPase may change according to the tissue expressions. On the renal cells, as well as on the brain and the heart, iron promotes an enzyme inactivation, whereas its effect on the erythrocytes seems to be the opposite, directly stimulating the ATPase activity, or stimulating it by signaling pathways involving ROS and PKC. Modulations in the ATPase activity may impair the ionic transportation, which is essential for cell viability maintenance, inducing irreversible damage to the cell homeostasis. Here, we will discuss about the iron overload effect on the P-ATPases, such as the Na⁺,K⁺-ATPase, the Ca²⁺-ATPase, and the Fe²⁺-ATPase.

Modification in oxidative processes in muscle tissues exposed to laser- and light-emitting diode radiation

Exposure of living tissues to high-intensity red or near-infrared light can produce the oxidative stress effects both in the target zone and adjacent ones. The protein oxidative modification (POM) products can be used as reliable and early markers of oxidative stress. The contents of modified proteins in the investigated specimens can be evaluated by the 2,4-dinitrophenylhydrazine assay (the DNPH assay). Low-intensity red light is able to decrease the activity of oxidative processes and the DNPH assay data about the POM products in the biological tissues could show both an oxidative stress level and an efficiency of physical agent protection against the oxidative processes. Two control groups of white rats were irradiated by laser light, the first control group by red light and the second one by near-infrared radiation (NIR).Two experimental groups were consequently treated with laser and red low-level light-emitting diode radiation (LED). One of them was exposed to red laser light + LED and the other to NIR + LED. The fifth group was intact. Each group included ten animals. The effect of laser light was studied by methods of protein oxidative modifications. We measured levels of both induced and spontaneous POM products by the DNPH assay. The dramatic increase in levels of POM products in the control group samples when compared with the intact group data as well as the sharp decrease in the POM products in the experimental groups treated with LED low-level light were statistically significant (p ≤ 0.05). Exposure of skeletal muscles to high-intensity red and near-infrared laser light causes oxidative stress that continues not less than 3 days. The method of measurement of POM product contents by the DNPH assay is a reliable test of an oxidative process rate. Red low-intensity LED radiation can provide rehabilitation of skeletal muscle tissues treated with high-intensity laser light.

Effects of electromagnetic fields exposure on the antioxidant defense system

Technological devices have become essential components of daily life. However, their deleterious effects on the body, particularly on the nervous system, are well known. Electromagnetic fields (EMF) have various chemical effects, including causing deterioration in large molecules in cells and imbalance in ionic equilibrium. Despite being essential for life, oxygen molecules can lead to the generation of hazardous by-products, known as reactive oxygen species (ROS), during biological reactions. These reactive oxygen species can damage cellular components such as proteins, lipids and DNA. Antioxidant defense systems exist in order to keep free radical formation under control and to prevent their harmful effects on the biological system. Free radical formation can take place in various ways, including ultraviolet light, drugs, lipid oxidation, immunological reactions, radiation, stress, smoking, alcohol and biochemical redox reactions. Oxidative stress occurs if the antioxidant defense system is unable to prevent the harmful effects of free radicals. Several studies have reported that exposure to EMF results in oxidative stress in many tissues of the body. Exposure to EMF is known to increase free radical concentrations and traceability and can affect the radical couple recombination. The purpose of this review was to highlight the impact of oxidative stress on antioxidant systems. Abbreviations: EMF, electromagnetic fields; RF, radiofrequency; ROS, reactive oxygen species; GSH, glutathione; GPx, glutathione peroxidase; GR, glutathione reductase; GST, glutathione S-transferase; CAT, catalase; SOD, superoxide dismutase; HSP, heat shock protein; EMF/RFR, electromagnetic frequency and radiofrequency exposures; ELF-EMFs, exposure to extremely low frequency; MEL, melatonin; FA, folic acid; MDA, malondialdehyde.

Protein Posttranslational Modifications: Roles in Aging and Age-Related Disease

Aging is characterized by the progressive decline of biochemical and physiological function in an individual. Consequently, aging is a major risk factor for diseases like cancer, obesity, and type 2 diabetes. The cellular and molecular mechanisms of aging are not well understood, nor is the relationship between aging and the onset of diseases. One of the hallmarks of aging is a decrease in cellular proteome homeostasis, allowing abnormal proteins to accumulate. This phenomenon is observed in both eukaryotes and prokaryotes, suggesting that the underlying molecular processes are evolutionarily conserved. Similar protein aggregation occurs in the pathogenesis of diseases like Alzheimer's and Parkinson's. Further, protein posttranslational modifications (PTMs), either spontaneous or physiological/pathological, are emerging as important markers of aging and aging-related diseases, though clear causality has not yet been firmly established. This review presents an overview of the interplay of PTMs in aging-associated molecular processes in eukaryotic aging models. Understanding PTM roles in aging could facilitate targeted therapies or interventions for age-related diseases. In addition, the study of PTMs in prokaryotes is highlighted, revealing the potential of simple prokaryotic models to uncover complex aging-associated molecular processes in the emerging field of microbiogerontology.

Consuming a Ketogenic Diet while Receiving Radiation and Chemotherapy for Locally Advanced Lung Cancer and Pancreatic Cancer: The University of Iowa Experience of Two Phase 1 Clinical Trials

Ketogenic diets are low in carbohydrates and high in fat, which forces cells to rely more heavily upon mitochondrial oxidation of fatty acids for energy. Relative to normal cells, cancer cells are believed to exist under a condition of chronic mitochondrial oxidative stress that is compensated for by increases in glucose metabolism to generate reducing equivalents. In this study we tested the hypothesis that a ketogenic diet concurrent with radiation and chemotherapy would be clinically tolerable in locally advanced non-small cell lung cancer (NSCLC) and pancreatic cancer and could potentially exploit cancer cell oxidative metabolism to improve therapeutic outcomes. Mice bearing MIA PaCa-2 pancreatic cancer xenografts were fed either a ketogenic diet or standard rodent chow, treated with conventionally fractionated radiation (2 Gy/fraction), and tumor growth rates were assessed daily. Tumors were assessed for immunoreactive 4-hydroxy-2-nonenal-(4HNE)-modfied proteins as a marker of oxidative stress. Based on this and another previously published preclinical study, phase 1 clinical trials in locally advanced NSCLC and pancreatic cancer were initiated, combining standard radiation and chemotherapy with a ketogenic diet for six weeks (NSCLC) or five weeks (pancreatic cancer). The xenograft experiments demonstrated prolonged survival and increased 4HNE-modfied proteins in animals consuming a ketogenic diet combined with radiation compared to radiation alone. In the phase 1 clinical trial, over a period of three years, seven NSCLC patients enrolled in the study. Of these, four were unable to comply with the diet and withdrew, two completed the study and one was withdrawn due to a dose-limiting toxicity. Over the same time period, two pancreatic cancer patients enrolled in the trial. Of these, one completed the study and the other was withdrawn due to a dose-limiting toxicity. The preclinical experiments demonstrate that a ketogenic diet increases radiation sensitivity in a pancreatic cancer xenograft model. However, patients with locally advanced NSCLC and pancreatic cancer receiving concurrent radiotherapy and chemotherapy had suboptimal compliance to the oral ketogenic diet and thus, poor tolerance.