• Molecules and Cells
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• v.39 no.1
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• pp.20-25
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• 2016

Photosynthesis is a highly robust process allowing for rapid adjustment to changing environmental conditions. The efficient acclimation depends on balanced redox metabolism and control of reactive oxygen species release which triggers signaling cascades and potentially detrimental oxidation reactions. Thiol peroxidases of the peroxiredoxin and glutathione peroxidase type, and ascorbate peroxidases are the main peroxide detoxifying enzymes of the chloroplast. They use different electron donors and are linked to distinct redox networks. In addition, the peroxiredoxins serve functions in redox regulation and retrograde signaling. The complexity of plastid peroxidases is discussed in context of suborganellar localization, substrate preference, metabolic coupling, protein abundance, activity regulation, interactions, signaling functions, and the conditional requirement for high antioxidant capacity. Thus the review provides an opinion on the advantage of linking detoxification of peroxides to different enzymatic systems and implementing mechanisms for their inactivation to enforce signal propagation within and from the chloroplast.

• KSBB Journal
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• v.10 no.3
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• pp.335-342
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• 1995

Solid and liquid phase peroxidases were extracted from Chinese cabbage roots by using commercial juicer in order to use peroxidases from agricultural waste for industrial applications. Since peroxidases are distributed into 66% in liquid (juice) and 34% in solid phase (pulp), enzymes from both phases were applied to investigate the enzymatic removal of phenol from waste water. After contacting 150 ppm Phenol solution with liquid phase enzyme (1,800 unit/$\ell$) for 3 hours in a batch stirred reactor, 96% of phenol could be removed through polymerization and precipitation. Also, phenol could be removed from initial 120ppm to 5ppm by applying solid phase enzyme in an air lift reactor ($600 unit/\ell$). Almost equivalent efficiencies of phenol removal were observed between two systems, even though only one third of the enzymes in batch stirred reactor was applied in airlift reactor. The possible reason for this phenomenon is because peroxidases exist as immobilized forms in solid phase.

• BMB Reports
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• v.42 no.9
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• pp.561-567
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• 2009

Although many plant-derived phenolic compounds display antioxidant effects in biological systems, their mechanism of action remains controversial. In this study, the mechanism by which p-coumaric acid (p-CA) performs its antioxidant action was investigated in bovine aortic endothelial cells under oxidative stress due to high levels of glucose (HG) and arachidonic acid (AA), a free fatty acid. p-CA prevented lipid peroxidation and cell death due to HG+AA without affecting the production of reactive oxygen species. The antioxidant effect of p-CA was not decreased by buthionine-(S,R)-sulfoximine, an inhibitor of cellular GSH synthesis. In contrast, pretreatment with p-CA caused the induction of peroxidases that decomposed t-butyl hydroperoxide in a p-CA-dependent manner. Furthermore, the antioxidant effect of p-CA was significantly mitigated by methimazole, which was shown to inhibit the catalytic activity of 'p-CA peroxidases' in vitro. Therefore, it is suggested that the induction of these previously unidentified 'p-CA peroxidases' is responsible for the antioxidant effect of p-CA.

• BMB Reports
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• v.44 no.8
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• pp.497-505
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• 2011

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.

• Molecules and Cells
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• v.39 no.1
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• pp.65-71
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• 2016

A challenge in the redox field is the elucidation of the molecular mechanisms, by which $H_2O_2$ mediates signal transduction in cells. This is relevant since redox pathways are disturbed in some pathologies. The transcription factor OxyR is the $H_2O_2$ sensor in bacteria, whereas Cys-based peroxidases are involved in the perception of this oxidant in eukaryotic cells. Three possible mechanisms may be involved in $H_2O_2$ signaling that are not mutually exclusive. In the simplest pathway, $H_2O_2$ signals through direct oxidation of the signaling protein, such as a phosphatase or a transcription factor. Although signaling proteins are frequently observed in the oxidized state in biological systems, in most cases their direct oxidation by $H_2O_2$ is too slow ($10^1M^{-1}s^{-1}$ range) to outcompete Cys-based peroxidases and glutathione. In some particular cellular compartments (such as vicinity of NADPH oxidases), it is possible that a signaling protein faces extremely high $H_2O_2$ concentrations, making the direct oxidation feasible. Alternatively, high $H_2O_2$ levels can hyperoxidize peroxiredoxins leading to local building up of $H_2O_2$ that then could oxidize a signaling protein (floodgate hypothesis). In a second model, $H_2O_2$ oxidizes Cys-based peroxidases that then through thiol-disulfide reshuffling would transmit the oxidized equivalents to the signaling protein. The third model of signaling is centered on the reducing substrate of Cys-based peroxidases that in most cases is thioredoxin. Is this model, peroxiredoxins would signal by modulating the thioredoxin redox status. More kinetic data is required to allow the identification of the complex network of thiol switches.

• Mycobiology
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• v.32 no.1
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• pp.47-53
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• 2004

Pseudomonas fluorescens 1-94 induced systemic resistance in chickpea against Fusarium wilt of chickpea caused by Fusarium oxysporum f. sp. ciceri by the synthesis and accumulation of phenolic compounds, phenylalanine ammonia lyase(PAL) and pathogenesis related(PR) proteins(chitinase, $\beta$-1,3-glucanase and peroxidase). Time-course accumulation of these enzymes in chickpea plants inoculated with P. fluorescens was significantly(LSD, P=0.05) higher than control. Maximum activities of PR-proteins were recorded at 3 days after inoculation in all induced plants; thereafter, the activity decreased progressively. Five PR peroxidases detected in induced chickpea plants. Molecular mass of these purified peroxidases was 20, 29, 43, 66 and 97 kDa. Purified peroxidases showed antifungal activity against plant pathogenic fungi.

• Proceedings of the Zoological Society Korea Conference
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• 1995.10b
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• pp.276.2-276
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• 1995

No Abstract, See Full Text

• Journal of Microbiology and Biotechnology
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• v.33 no.3
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• pp.299-309
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• 2023

Glutathione peroxidases (Gpx) are a group of antioxidant enzymes that protect cells or tissues against damage from reactive oxygen species (ROS). The Gpx proteins identified in mammals exhibit high catalytic activity toward glutathione (GSH). In contrast, a variety of non-mammalian Gpx proteins from diverse organisms, including fungi, plants, insects, and rodent parasites, show specificity for thioredoxin (TRX) rather than GSH and are designated as TRX-dependent peroxiredoxins. However, the study of the properties of Gpx in the environmental microbiome or isolated bacteria is limited. In this study, we analyzed the Gpx sequences, identified the characteristics of sequences and structures, and found that the environmental microbiome Gpx proteins should be classified as TRX-dependent, Gpx-like peroxiredoxins. This classification is based on the following three items of evidence: i) the conservation of the peroxidatic Cys residue; ii) the existence and conservation of the resolving Cys residue that forms the disulfide bond with the peroxidatic cysteine; and iii) the absence of dimeric and tetrameric interface domains. The conservation/divergence pattern of all known bacterial Gpx-like proteins in public databases shows that they share common characteristics with that from the environmental microbiome and are also TRX-dependent. Moreover, phylogenetic analysis shows that the bacterial Gpx-like proteins exhibit a star-like radiating phylogenetic structure forming a highly diverse genetic pool of TRX-dependent, Gpx-like peroxidases.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.93-95
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• 2003

Selenium is an ultra trace essential element for the normal functioning body because of forming the active center of redox enzymes such as four kinds of glutathione peroxidases (GPx), thioredoxin reductase (TR) and 5'-iodothyronine deiodinase. However, the adequate range between deficient and excessive levels is very narrow. (omitted)

• BMB Reports
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• v.29 no.1
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• pp.52-57
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• 1996

A specific DNA fragment from Korean radish (Raphanus sativus L.) was amplified by performing PCR with oligonucleotide primers which correspond to the highly conserved regions of plant peroxidases. The size of the PCR product was ca. 400 bp, as expected from the known plant peroxidase genes. Comparison of the nucleotide and deduced amino acid sequences of the PCR product to those of other plant peroxidase-encoding genes revealed that the amplified fragment corresponded to the highly conserved region I and III of plant peroxidases. By screening a genomic library of Korean radish using the amplified fragment as a probe, two positive clones, named prxK1 and prxK2, were isolated. Restriction mapping studies indicated that the 5.2 kb Sail fragment of the prxK1 clone and the 4.0 kb EcoRI fragment of the prxK2 clone encode separate isoperoxidase genes. Analyses of the promoter region of the prxK1 clone shows that putative CAAT box, CMT box, and TGA1b binding sequence (5' TGACGT) are present 718 bp upstream from the start codon.