Role Of Peroxidase Research Articles

The Roles of Peroxidase and Phospholipase A2Activities of Peroxiredoxin 6 in Protecting Pulmonary Microvascular Endothelial Cells Against Peroxidative Stress

Peroxiredoxin 6 (Prdx6), a bifunctional enzyme with glutathione peroxidase and phospholipase A(2) (PLA(2)) activities, has been demonstrated as playing a critical role in antioxidant defense of the lung. Our aim was to evaluate the relative role of each activity in Prdx6-mediated protection of mouse pulmonary microvascular endothelial cells (PMVECs) against the peroxidative stress of treatment with tert-butyl hydroperoxide (tBOOH). PMVEC from Prdx6 null mice showed increased lethality on tBOOH exposure (50-200 μM) compared with wild-type (WT) controls. Treatment with 1-hexadecyl-3-trifluoroethylglycero-sn-2-phosphomethanol (MJ33), a Prdx6 PLA(2) activity inhibitor, increased the sensitivity of WT cells to peroxidative stress, but did not further sensitize Prdx6 null cells. Lethality in Prdx6 null PMVEC was "rescued" by transfection with a construct leading to the expression of WT rat Prdx6. Expression of mutant Prdx6 with either peroxidase activity or PLA(2) activity alone each partially rescued the survival of Prdx6 null cells, while constructs with both active sites mutated failed to rescue. Co-transfection with two different constructs, each expressing one activity, rescued cells as well as the WT construct. Contrary to the general assumption that the peroxidase activity is the main mechanism for Prdx6 antioxidant function, these results indicate that the PLA(2) activity also plays a substantial role in protecting cells against oxidant stress caused by an exogenous hydroperoxide.

The role of peroxidases in the pathogenesis of atherosclerosis

Reactive oxygen species (ROS), which include superoxide anions and peroxides, induce oxidative stress, contributing to the initiation and progression of cardiovascular diseases involving atherosclerosis. The endogenous and exogenous factors hypercholesterolemia, hyperglycemia, hypertension, and shear stress induce various enzyme systems such as nicotinamide adenine dinucleotide (phosphate) oxidase, xanthine oxidase, and lipoxygenase in vascular and immune cells, which generate ROS. Besides inducing oxidative stress, ROS mediate signaling pathways involved in monocyte adhesion and infiltration, platelet activation, and smooth muscle cell migration. A number of antioxidant enzymes (e.g., superoxide dismutases, catalase, glutathione peroxidases, and peroxiredoxins) regulate ROS in vascular and immune cells. Atherosclerosis results from a local imbalance between ROS production and these antioxidant enzymes. In this review, we will discuss 1) oxidative stress and atherosclerosis, 2) ROS-dependent atherogenic signaling in endothelial cells, macrophages, and vascular smooth muscle cells, 3) roles of peroxidases in atherosclerosis, and 4) antioxidant drugs and therapeutic perspectives.

Role of peroxidases in the compensation of cytosolic ascorbate peroxidase knockdown in rice plants under abiotic stress

Current studies, particularly in Arabidopsis, have demonstrated that mutants deficient in cytosolic ascorbate peroxidases (APXs) are susceptible to the oxidative damage induced by abiotic stress. In contrast, we demonstrate here that rice mutants double silenced for cytosolic APXs (APx1/2s) up-regulated other peroxidases, making the mutants able to cope with abiotic stress, such as salt, heat, high light and methyl viologen, similar to non-transformed (NT) plants. The APx1/2s mutants exhibited an altered redox homeostasis, as indicated by increased levels of H₂O₂ and ascorbate and glutathione redox states. Both mutant and NT plants exhibited similar photosynthesis (CO₂) assimilation and photochemical efficiency) under both normal and stress conditions. Overall, the antioxidative compensatory mechanism displayed by the mutants was associated with increased expression of OsGpx genes, which resulted in higher glutathione peroxidase (GPX) activity in the cytosolic and chloroplastic fractions. The transcript levels of OsCatA and OsCatB and the activities of catalase (CAT) and guaiacol peroxidase (GPOD; type III peroxidases) were also up-regulated. None of the six studied isoforms of OsApx were up-regulated under normal growth conditions. Therefore, the deficiency in cytosolic APXs was effectively compensated for by up-regulation of other peroxidases. We propose that signalling mechanisms triggered in rice mutants could be distinct from those proposed for Arabidopsis.

In VitroStudies of DNA Damage Caused by Tricyclic Antidepressants: A Role of Peroxidase in the Side Effects of the Drugs

Studies show that tricyclic antidepressants prescribed for migraines, anxiety, and child enuresis have numerous adverse effects in living cells. One of the undesired outcomes observed under treatment with these drugs is DNA damage. However, the mechanisms underlying damage have yet to be elucidated. We performed in vitro studies of the DNA damage caused by four tricyclic antidepressants: imipramine, amitriptyline, opipramol, and protriptyline. We focused particularly on the DNA damage aided by peroxidases. As a model of a peroxidase, we used horseradish peroxidase (HRP). At pH 7, reactions of HRP with excess hydrogen peroxide and imipramine yielded an intense purple color and a broad absorption spectrum with the maximum intensity at 522 nm. Reactions performed between DNA and imipramine in the presence of H(2)O(2) and HRP resulted in the disappearance of the DNA band. In the case of the other three drugs, this effect was not observed. Extraction of the DNA from the reaction mixture indicated that DNA is degraded in the reaction between imipramine and H(2)O(2) catalyzed by HRP. The final product of imipramine oxidation was identified as iminodibenzyl. We hypothesize that the damage to DNA was caused by an imipramine reactive intermediate.

Peroxidase Activity In the Sulfate-Reducing Bacterium Desulfotomaculum acetoxidans DSM 771

Earlier research demonstrated the secretion of benzoate, which must be oxygenated to its 4-hydroxy derivative in order to be included in further sulfate uptake processes. The present study on Desulfotomaculum acetoxidans DSM 771 was designed to determine the activity and catalytic specificity of the enzyme (most probably peroxidase) catalyzing the hydroxylation of secreted benzoate. Peroxidase activity measured with ABTS (2,2'-azino-bis (3-ethylbenzathiazoline-6-sulfonic acid) during cultivation indicated the greatest activity on the third and thirteen days (3.4 and 2.3 nkat per ml sample respectively). The highest (0.7979) correlation coefficient was calculated between peroxidase activity and hydrogen peroxide levels. The cell walls from 3- and 13-day cultures were subjected to an isolation procedure, PIPES (piperazine-N,N'-bis (2-ethane-sulfonic acid) extract followed by preparative electrophoresis. The extracts of a approximately 30 kDa band on the gel were analyzed by Western blotting and the membrane was stained with TMB (3,3',5,5'-tetramethylbenzidine-specific for the presence of peroxidase). This same protein was incubated for 6 h with benzoate, H2O2, Na2SO4. The product formed a complex with Fe3+, whose maximum absorption spectra (501.7 nm) corresponded with a ferric complex of synthetic 4-hydroxy-3-sulfo-benzoate. The H2S level during the cultivation was higher in culture grown with 15.5 mM 4-hydroxy-3-sulfo-benzoate than in culture with lactate supplemented with 15.5 mM sulfate. The role of peroxidase in oxygen utilization and sulfate uptake is discussed.

A New Staining Method for the Distribution of Peroxidase with Luminol and Its Application for the Germination of Brown Rice in the Presence of Hydrogen Peroxide

We developed a new staining method for the distribution of peroxidase (POD), which is a coloration caused by the reaction between luminol and hydrogen peroxide in the presence of POD. Using this method, the hydrogen peroxide revelation promoted the extension of bud and the induction of peroxidase on the germination of brown rice. From the above result, this method has been determined to be a useful technique for studing its role for POD in plants.

Peroxidase mediated decolorization and remediation of wastewater containing industrial dyes: a review

In this article an effort has been made to review literature based on the role of peroxidases in the treatment and decolorization of a wide spectrum aromatic dyes from polluted water. Peroxidases can catalyze degradation/transformation of aromatic dyes either by precipitation or by opening the aromatic ring structure. Peroxidases from plant sources; horseradish, turnip, tomato, soybean, bitter gourd, white radish and Saccharum uvarum and microbial sources; lignin peroxidases, manganese peroxidases, vanadium haloperoxidases, versatile peroxidases, dye decolorizing peroxidases have been employed for the remediation of commercial dyes. Soluble and immobilized peroxidases have been successfully exploited in batch as well as in continuous processes for the treatment of synthetic dyes with complex aromatic molecular structures present in industrial effluents at large scale. However, recalcitrant dyes were also decolorized by the action of peroxidases in the presence of redox mediators.

The first genome-level transcriptome of the wood-degrading fungus Phanerochaete chrysosporium grown on red oak

As part of an effort to determine all the gene products involved in wood degradation, we have performed massively parallel pyrosequencing on an expression library from the white rot fungus Phanerochaete chrysosporium grown in shallow stationary cultures with red oak as the carbon source. Approximately 48,000 high quality sequence tags (246 bp average length) were generated. 53% of the sequence tags aligned to 4,262 P. chrysosporium gene models, and an additional 18.5% of the tags reliably aligned to the P. chrysosporium genome providing evidence for 961 putative novel fragmented gene models. Due to their role in lignocellulose degradation, the secreted proteins were focused upon. Our results show that the four enzymes required for cellulose degradation: endocellulase, exocellulase CBHI, exocellulase CBHII, and beta-glucosidase are all produced. For hemicellulose degradation, not all known enzymes were produced, but endoxylanases, acetyl xylan esterases and mannosidases were detected. For lignin degradation, the role of peroxidases has been questioned; however, our results show that lignin peroxidase is highly expressed along with the H(2)O(2) generating enzyme, alcohol oxidase. The transcriptome snapshot reveals that H(2)O(2) generation and utilization are central in wood degradation. Our results also reveal new transcripts that encode extracellular proteins with no known function.

Changes in peroxidase activity in sunflower during infection by necrotrophic pathogen Alternaria helianthi

Detailed analysis of threshold levels of resistance in sunflower genotypes to Alternaria helianthi and its relation to peroxidase activity was carried out. Fourteen sunflower genotypes were categorized into resistant, moderately resistant, susceptible and highly susceptible groups based on field reaction on disease rating scale of 0 – 9. Sunflower genotypes MSH-59 and PF-56 were resistant with disease reaction scale of 3, PC-63, PC-64, RHA6D-1 and G-47 were moderately resistant with disease reaction scale of 5, CMS-859, PC-52, AC-48, R-265, CMS-338 and MR-1 were susceptible with a disease reaction scale of 7, Morden and CMS-62 belonged to a highly susceptible category with a disease reaction scale of 8. Time-course study of peroxidase (PO) activity was analysed in resistant (MSH-59) and susceptible (Morden) sunflower genotypes using spectrophotometry. High PO activity was recorded at 2 and 12 h post-inoculation with A. helianthi. At 2 h post-inoculation, resistant genotypes recorded 12.8 units while the susceptible genotype had 2.4 units of PO activity. At 12 h PO activity increased to 39.2 and 4.2 units in resistant and highly susceptible genotypes respectively. Treatment with antioxidant inhibitors sodium azide and sodium metabisulphite at various molar concentrations reduced the pathogen-induced as well as constitutive levels of PO activity. Pre-treatment of resistant sunflower genotypes with inhibitor followed by pathogen inoculation increased the disease reaction when compared to control. Higher PO activities were recorded in sunflower genotypes with high threshold levels of resistance and lesser in susceptible genotype. The study therefore gives strong evidence for the role of PO as an important enzyme of the central defense system against necrotrophic pathogen A. helianthi and could be used as a reliable biomarker for assessing resistance.

The role of peroxidases weakly bound to the cell walls in potato resistance to ring rot infection

The role of peroxidases weakly bound to the cell walls in potato resistance to ring rot infection

Possible peroxidase functions in the interaction between the parasitic plant, Orobanche aegyptiaca, and its host, Arabidopsis thaliana

The mechanism by which the flowering holoparasitic plant, Orobanche aegyptiaca, infects its host without evoking a defence mechanism is still poorly understood. In this work, we studied several mechanisms used by phytopathogenic fungi. We focussed on the possible role of peroxidases during O. aegyptiaca penetration into the roots of Arabidopsis thaliana. A convenient experimental system for studying the interaction under sterile conditions was developed. The formation of extracellular reactive oxygen species (ROS) was detected at the interaction site before, during, and after the parasite penetrated into the host. These extracellular ROS probably originated from the parasite. However, no intracellular ROS could be detected at the site of the interaction. Peroxidase activity was observed mainly at the apex of the root of the parasite and in the adventitious roots of the tubercle. Benzhydroxamic acid, a peroxidase inhibitor, was used to probe the possible role of peroxidase in the infection process. Peroxidase activity was observed in the root apex and adventitious roots of O. aegyptiaca, but no evidence was found for its participation in the actual infection process. Peroxidase activity was also found in the later stages of the interaction between the host and the parasite. We propose that peroxidases could have a role in generating extracellular ROS for loosening the cell wall of the host in order to facilitate penetration. Alternatively, the ROS could act in facilitating the root elongation of the parasite.

Senescence in rose (Rosa hybrida L.): role of the endogenous anti-oxidant system

SummaryThe role of oxidative stress during petal senescence in rose was investigated. Two cut-rose (Rosa hybrida L.) cultivars, ‘Grand Gala’ and ‘First Red’ were obtained from a commercial grower. Petals were harvested from seven different whorls, outermost-to-innermost in flowers of both cultivars. H2O2 production was determined throughout flower bud senescence, and the H2O2-scavenging enzyme system was studied. The activities of catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APOD) increased up to Stage-5 of flower bud development (petals completely unfolded) and declined thereafter. The highest level of glutathione reductase (GR) activity was observed at Stage-4 (sepals completely opened, petal starting to unfold), followed by a significant decrease at later stages, coincident with higher levels of ethylene production. This limits the role of APOD from Stage-4 onward and is responsible for the failure of free radical scavenging in rose petals. In this context, the role of POD becomes important in protecting the flower from free radicals. Thus, an increase in endogenous H2O2 levels and a decrease in anti-oxidant enzyme activities may be partly responsible for initiating senescence in rose petals.

The role of peroxidase on the antioxidant potential of fresh-cut ‘Piel de Sapo’ melon packaged under different modified atmospheres

The effects of different initial in-package O 2 and CO 2 concentrations (2.5 kPa O 2 + 7 kPa CO 2, 10 kPa O 2 + 7 kPa CO 2, 21 kPa O 2, 30 kPa O 2 and 70 kPa O 2) on peroxidase activity, vitamin C content, total phenolics and antioxidant capacity of fresh-cut ‘Piel de Sapo’ melon have been investigated for 14 days at 4 °C. The radical scavenging activity of fresh-cut melon strongly increased after 9 days storage related to a synthesis of phenolic compounds, especially under 2.5 kPa O 2 + 7 kPa CO 2 atmospheres. Low O 2 levels best maintained vitamin C and phenolic content during the storage. However, stressful too-low O 2 and high CO 2 levels induced an important increase of peroxidase activity under 2.5 kPa O 2 + 7 kPa CO 2 atmosphere, which was directly related to changes of vitamin C throughout storage. Therefore, 70 kPa O 2 atmospheres are proposed to prevent anaerobic conditions during storage of fresh-cut melon and thus, reduce wounding stress and deteriorative changes related to high peroxidase activity in tissue.

Role of peroxidases, thiols and Bak/Bax in tumor cell susceptibility to Cu[DEDTC] 2

Copper and two molecules of diethyl dithiocarbamate [DEDTC] form the Cu[DEDTC] 2 complex, which shows cytotoxicity against melanoma and carcinoma cells, making it a potentially useful anti-cancer agent. The differential response to Cu[DEDTC] 2 in susceptible human SKBR3 carcinoma and C8161 melanoma cell variants of moderate and high resistance to this organometallic complex was evaluated in this study. Both cell lines underwent apoptosis-associated PARP cleavage, changes in expression of nuclear NFkB p65, p21WAF1 and cyclin A, with loss of clonogenicity in response to this agent. However, a threefold greater concentration [IC 50 0.6 μM DEDTC: 0.3 μM Cu] was required to kill moderately resistant C8161 melanoma compared to highly susceptible SKBR3 cells. Decreased susceptibility to Cu[DEDTC] 2 in C8161 melanoma correlated with greater levels of glutathione peroxidase and catalase, and a fourfold lower requirement for N-acetyl cysteine (1 mM) to overcome toxicity. Whereas melanoma cells selected for resistance to [0.8 μM DEDTC: 0.4 μM Cu] showed persistent catalase and GPx activity, melanoma cells with moderate susceptibility showed decreased catalase and Gpx when responding to treatment. Cytotoxic response in moderately susceptible C8161 melanoma cells involved an early accumulation of pro-apoptotic Bax in the G2 cell cycle phase, followed by an increased ratio of pro-apoptotic Bak to anti-apoptotic Mcl-1 in mitochondria. Our data suggests that Cu[DEDTC] 2 toxicity is mediated through an increase in pro-apoptotic Bak/Bax via disruption of the peroxide and thiol metabolism.

The relationship between respiration rate and peroxidase activities in maize root mitochondria

In the present study we provide the evidence of different respiration rates and peroxidase activities in maize (Zea mays L.) mitochondria isolated from germinated seeds and roots of 2-week-old seedlings. The negative relationships between mitochondrial respiration rate measured with NADH as substrate and activities of peroxidases that oxidized NADH in both oxidative and peroxidative cycles were found. The possible role of peroxidase in the regulation of reactive oxygen species metabolism in expense of NADH oxidation was hypothesized.

A peroxidase gene expressed during early developmental stages of the parasitic plant Orobanche ramosa

Broomrapes (Orobanche spp.) are holoparasitic weeds that cause devastating losses in many economically important crops. The molecular mechanisms that control the early stages of host infection in Orobanche are poorly understood. In the present study, the role of peroxidase has been examined during pre-infection growth and development of O. ramosa, using an in vitro model system. Peroxidase activity was histochemically localized at the tips of actively growing radicles and nascent attachment organs. Addition of exogenous catalase resulted in a significant reduction in the apical growth rate of the radicle. The prx1 gene encoding a putative class III peroxidase was cloned from a cDNA library of O. ramosa and was found to be expressed specifically during the early stages of the parasitic life cycle. The exogenous addition of sucrose resulted in significantly reduced prx1 transcript levels and in a dramatic change in radicle development from polarized apical growth to isotropic growth and the formation of tubercle-like structures. The results indicate an important role of peroxidases during the early parasitic stages of Orobanche.

Oxidative coupling of a feruloyl-arabinoxylan trisaccharide (FAXX) in the walls of living maize cells requires endogenous hydrogen peroxide and is controlled by a low-Mr apoplastic inhibitor

Feruloyl-polysaccharides can be oxidatively coupled in isolated cell walls by peroxidase plus exogenous H(2)O(2) in vitro, but the extent to which similar reactions may occur in the apoplast in vivo was unclear. Numerous cellular factors potentially control feruloyl coupling in vivo, and their net controlling influence is not readily studied in vitro. Therefore, we have monitored apoplastic feruloyl coupling in cultured maize cells in vivo using a radiolabelled model substrate, 5-O-feruloyl-alpha-L: -arabinofuranosyl-(1-->3)-beta-D: -xylopyranosyl-(1-->4)-D: -xylose (FAXX). FAXX was expected to permeate the wall and to undergo reactions analogous to those normally exhibited by apoplastic feruloyl-polysaccharides in vivo. Little difference was found between the fates of [feruloyl-(14)C]FAXX and [pentosyl-(3)H]FAXX, indicating negligible apoplastic hydrolase or transferase activities. Very little radioactivity entered the protoplasm. Maize cells that had recently been washed in fresh medium were able to bind most of the FAXX (90%) in their cell walls, regardless of the age of the culture. During wall-binding, the [(14)C]feruloyl groups were converted to [(14)C]dehydrodiferulates and larger coupling products, as revealed by TLC after alkaline hydrolysis. As expected for an oxidative reaction, wall-binding was delayed by added anti-oxidants (ascorbate, ferulate, sinapate, chlorogenate or rutin). It was also completely inhibited by iodide, an H(2)O(2)-scavenger, indicating a role for peroxidase rather than oxidase. The observations indicate that oxidative coupling of feruloyl groups occurred within the cell wall, dependent on endogenous apoplastic H(2)O(2) and wall-localised peroxidase, in vivo. Cells that had not recently been washed in fresh medium were much less able to bind FAXX, indicating the presence in the apoplast of an endogenous inhibitor of oxidative coupling. This inhibitor was of low M(r), was destroyed by heating, and remained in the aqueous phase (pH approximately 3.5) when shaken with ethyl acetate. Its effectiveness was not altered by ascorbate oxidase. It is thus a small, heat-labile, hydrophilic inhibitor (not ascorbate) which we suggest plays a natural role in the control of wall cross-linking, and thus potentially in the control of cell growth.

Hydrogen peroxide localization and antioxidant status in the recovery of apricot plants from European Stone Fruit Yellows

Hydrogen peroxide (H2O2) localization and roles of peroxidases, malondialdehyde and reduced glutathione were compared in leaves of apricot (Prunus armeniaca) plants: asymptomatic, European Stone Fruits Yellows (ESFY)-symptomatic and recovered. Nested PCR analysis revealed that ‘Candidatus Phytoplasma prunorum’, is present in asymptomatic, symptomatic and recovered apricot trees, confirming previous observations on this species, in which recovery does not seem to be related to the disappearance of phytoplasma from the plant. H2O2 was detected cytochemically by its reaction with cerium chloride, which produces electron-dense deposits of cerium perhydroxides. H2O2 was present in the plasmalemma of the phloem cells of recovered apricot plant leaves, but not in the asymptomatic or symptomatic material. Furthermore, by labelling apricot leaf tissues with diaminobenzidine DAB, no differences were found in the localization of peroxidases. Protein content in asymptomatic, symptomatic and recovered leaves was not significantly different from one another. In contrast, guaiacol peroxidase activity had the following trend: symptomatic > recovered > asymptomatic, whereas reduced glutathione content followed the opposite trend: asymptomatic > recovered > symptomatic. Moreover, no differences were observed in malondialdehyde concentrations between asymptomatic, symptomatic and recovered leaves. The overall results suggest that H2O2 and related metabolites and enzymes appear to be involved in lessening both pathogen virulence and disease symptom expression in ESFY-infected apricot plants.

Role of peroxidases in Parkinson disease: a hypothesis

Extensive research has been done to elucidate the underlying molecular events causing neurodegenerative diseases such as Parkinson disease, yet the cause and the individual steps in the progression of such diseases are still unknown. Here we advance the hypothesis that, rather than or in addition to inorganic radical molecules, heme-containing peroxidase enzymes may play a major role in the etiology of Parkinson disease. This hypothesis is based on the following considerations: (1) several heme-containing enzymes with peroxidase activity are present in the substantia nigra pars compacta; (2) these peroxidases have the ability to catalyze the oxidation of proteins and lipids; (3) certain heme peroxidases are known to destroy cells in vivo; (4) heme peroxidases have the stability and specificity that could account for the fact that specific molecules and cells are subject to damage in Parkinson disease, rather than a random destruction; (5) heme peroxidase activity could account for certain reactions in connection with parkinsonism that thus far have not been adequately explained; and (6) the participation of a heme peroxidase could explain some recent observations that are inconsistent with the oxyradical theory. The peroxidase-catalyzed oxidative pathway proposed here does not preclude the participation of apoptosis as an additional mechanism for cell destruction.

Role of peroxidase in anthocyanin degradation in litchi fruit pericarp

Postharvest browning of litchi fruit pericarp is a major problem, resulting in accelerated shelf life and reduced commercial value of the fruit. The browning was generally thought to be a rapid degradation of red pigments caused by polyphenol oxidase (PPO) and peroxidase (POD). This work is conducted to understand the role of POD in anthocyanin degradation in litchi pericarp, which is less understood than PPO. POD activity in the pericarp increased consistently with skin browning index during storage of litchi fruit, but was negatively associated with anthocyanin concentration. Although POD cannot directly oxidize litchi anthocyanin in the presence of H2O2 in vitro, the anthocyanin content decreased rapidly after the addition of guaiacol solution, which indicated that the anthocyanin degradation by POD exhibited a coupled oxidation mechanism. Furthermore, anthocyanidin, produced by hydrolysis of the purified anthocyanin, could act as a substrate of POD. Thus, enzymatic browning of litchi fruit pericarp caused by POD may involve an anthocyanase–anthocyanin–phenolic–H2O2 reaction.