• Korean Journal of Food Science and Technology
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• v.19 no.6
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• pp.506-514
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• 1987

Peroxidase was purified to a homogeneous state from Castanea Semen by ammonium sulfate precipitation, DEAE-cellulose column chromatography, gel filtration on sephadex G-100 and HPLC, and the purification fold was 65.3. The molecular weight of the enzyme was estimated to be about 35,000 by HPLC. In properties of the enzyme which was purified up to sephadex G-100 column chromatography, the optimum pH and temperature were 5.0 and $50^{\circ}C$, respectively. By heating the enzyme at $80^{\circ}C$ for 1.73 min., the enzyme activity was decreased to 10%. The enzyme was active toward aromatic amines such as o-phenylenediamine and p-phenylendiamine. Kinetic studies indicated a Km of 2.6mM for o-phenylenediamine at an optimal hydrogen-peroxide concentration and a Km of 10mM for hydrogenperoxide at an optimal o-phenylenediamine concentration. Among the reagents tested, L-ascorbic acid and sodium L-ascorbate inhibited significantly the enzyme, while $Ca^{++}$ and $Ba^{++}$ activated the enzyme at the concentration of 1mM and 5mM.

• The Korean Journal of Ecology
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• v.25 no.6
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• pp.371-377
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• 2002

Leaves of two-week old seedlings of tomato (Lycopersicon esculentum) were treated with various concentrations (0, 0.2 and 0.4 $\mu$g/1) of 2,4,5-trichlorobiphenyl (PCB-29) and subsequent growth of seedlings, symptoms of oxidative stress and activities of antioxidant enzymes were investigated. Compared with the non-treated control, foliar application of PCB-29 decreased both biomass and superoxide ($O_2$) radical production but increased hydrogen peroxide production and lipid peroxidation such as malondialdehyde (MDA) formation with increased activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX). Further studies on the isozymes of SOD, peroxidase (POD) and APX showed that all three isozymes of SOD such as Mn-SOD, Fe-SOD and Cu/Zn-SOD, two among four isozymes of POD and all three isozymes of APX were selectively increased in response to PCB. Therefore, we suggest that a possible cause for the reduction of seedling growth by PCB exposure is the oxidative stress including over production of hydrogen peroxide and the selective expression of specific isozymes of some antioxidant enzymes.

• Journal of Plant Biotechnology
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• v.50
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• pp.76-81
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• 2023

As cultured plant cells can grow in high oxidative stress conditions, they form an excellent system to study antioxidant mechanisms and the mass production of antioxidants. Oxidative stress is a major cause of damage in plants exposed to various types of environmental stress, including heavy metals, such as cadmium (Cd). Heavy metal accumulation can interfere with many cell functions and plant growth. To evaluate the contribution of oxidative stress to Cd-induced toxicity, cultured sweetpotato (Ipomoea batatas) cells were treated with increasing concentrations of Cd (0, 10, 25, and 50 μM) and cultured further. Cell growth was significantly inhibited by 25 and 50 μM of Cd, and the total protein content increased with 50 μM of Cd. Additionally, the activity of peroxidase (POD) and ascorbate peroxidase (APX), antioxidant enzymes that remove hydrogen peroxide (a reactive oxygen species), increased in the cells after treatment with 50 μM of Cd. The expression analysis of POD, APX, and peroxiredoxin (PRX) isolated from sweetpotato cultured cells in a previous study revealed the differential expression of POD in response to Cd. In this study, the expression levels of several acidic POD (swpa2, swpa3, and swpa4) and basal POD (swpb1, swpb2, and swpb3) genes were increased in Cd-treated cultured cells. These results indicate that Cd-mediated oxidative stress is closely linked to improved POD-mediated antioxidant defense capacity in sweetpotato suspension-cultured cells.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.164-170
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• 1999

This experiment was carried out to elucidate change of antioxidant enzymes activities subjected to water stresses in soybean plant. In this study, we measured the activities of ascorbate peroxidase(APDX), monodehydroascorbate reductase(MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase(GR) subjected to drought or flooding stresses for 4days and following recovery for 3days. Leaves of two soybean lines subjected to drought or flooding showed premature senescence as evidenced by the decrease in water content and total soluble protein content but those of soybean leaves was increased when stresses were recovered for 3days. The activities of APDX and GR subjected to drought or flooding were the decrease but those of enzymes were recovered when water stress was recovered. The activities of MDHAR with drought or flooding were on the decrease, whereas those of DHAR were increased, respectively. Antioxidant contents decreased continually subjected to drought or flooding but it recovered after 3 days subjected to water stresses.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.235-235
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• 2017

Chromium (Cr) toxicity is hazardous to the seed germination, growth, and development of plants. ${\gamma}$-Aminobutyric acid (GABA) is a non-protein amino acid and is involved in stress tolerance in plants. To investigate the effects of GABA in alleviating Cr toxicity, we treated eight-d-old mustard (Brassica juncea L.) seedlings with Cr (0.15 mM and 0.3 mM $K_2CrO_4$, 5 days) alone and in combination with GABA ($125{\mu}M$) in a semi-hydroponic medium. The roots and shoots of the seedlings accumulated Cr in a dose-dependent manner, which led to an increase in oxidative damage [lipid peroxidation; hydrogen peroxide ($H_2O_2$) content; superoxide ($O{_2}^{{\cdot}-}$) generation; lipoxygenase (LOX) activity], MG content, and disrupted antioxidant defense and glyoxalase systems. Chromium stress also reduced growth, leaf relative water content (RWC), and chlorophyll (chl) content but increased phytochelatin (PC) and proline (Pro) content. Furthermore, supplementing the Cr-treated seedlings with GABA reduced Cr uptake and upregulated the non-enzymatic antioxidants (ascorbate, AsA; glutathione, GSH) and the activities of the enzymatic antioxidants including ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT), glyoxalase I (Gly I), and glyoxalase II (Gly II), and finally reduced oxidative damage. Adding GABA also increased leaf RWC and chl content, decreased Pro and PC content, and restored plant growth. These findings shed light on the effect of GABA in improving the physiological mechanisms of mustard seedlings in response to Cr stress.

• Journal of Korean Society of Forest Science
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• v.96 no.3
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• pp.369-375
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• 2007

We examined two Populus species (Populus euramericana and Populus alba ${\times}$ Populus glandulosa) trees grown under livestock waste leachate treatment in the field. We investigated their physiological properties (photosynthetic rate, chlorophyll contents, transpiration rate and intercellular $CO_2$ concentration) and antioxidant enzyme activities. Ascorbate peroxidase and glutathione reductase were analyzed. According to our measurements, P. euramericana at control site showed a lower total chlorophyll contents, photosynthetic rate, intercellular $CO_2$ concentration, transpiration and stomatal conductance than those of trees at treatment site. P. alba ${\times}$ P. glandulosa showed low stomatal conductance and low photosynthetic rate.

• Journal of Plant Biotechnology
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• v.31 no.2
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• pp.109-113
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• 2004

In order to develop transgenic potato plants with enhanced tolerance to multiple stress, we constructed the transformation vector expressing both superoxide dismutase and ascorbate peroxidase genes in chloroplasts under the control of a stress-inducible SWPA2 promoter. Transgenic potato plants (cv. Superior and Atlantic) were generated using an Agrobacterium-mediated transformation system. Transgenic potato plants were regenerated on MS medium containing 100mg/L kanamycin. Genomic Southern blot analysis confirmed the incorporation of foreign genes into the potato genome. When potato leaf discs were subjected to methyl viologen (MV) at 10 $\mu$M, transgenic plants showed higher tolerance than non-transgenic or vector-transformed plants. To further study we selected the transgenic plant lines with enhanced tolerance against MV. These plants will be used for further analysis of stress-tolerance to multiple environmental stresses.

• Horticultural Science & Technology
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• v.31 no.4
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• pp.490-495
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• 2013

Two chrysanthemum varieties, 'ARTI-purple' and 'ARTI-queen', were chronically irradiated with doses of 30, 50, 70, and 100 Gy for four weeks in gamma-phytotron, a long term irradiation facility. We investigated the growth, responses of antioxidant enzymes (ascorbate peroxidase, APX; catalase, CAT; peroxidase, POD; superoxidase dismutase, SOD) and malondialdehyde (MDA) contents under different doses of chronic-irradiation. The five plant growth measurements including plant height, number of leaves, internode length, stalk diameter and leaf thickness were investigated immediately after four week irradiation. The plant height (p<0.001), internode length (p<0.01), the number of leaves (p<0.001) and stalk diameter (p<0.05) were significantly decreased an increasing doses of gamma-ray. Among them, especially, the internode length was remarkably decreased showing the RD50 (Reduction Dose 50) at approximately 65 Gy. The antioxidant response after four weeks of recovery period, ascorbate peroxidase (APX) (p<0.01), superoxide dismutase (SOD) (p<0.01) and peroxidase (POD) (p<0.001) were significantly increased with an increasing dose of gamma-ray. And malondialdehyde (MDA) (p<0.01) contents showed the significant increase at the 70 and 100 Gy which means the oxidative stress was lasting for a considerable period. In this study, the 50 Gy irradiation as optimal dose showed higher growth than the $RD_{50}$, it also showed insignificant differences on the antioxidant responses and MDA contents. However, the 100 Gy dose showed lower growth than $RD_{50}$.

• Journal of Life Science
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• v.28 no.7
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• pp.772-777
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• 2018

To understand the adaptability of Leymus chinensis forage grass to environmental stresses, we analyzed the $H_2O_2$ scavenging activity based on several antioxidant enzymes and total phenolics content, including peroxidase (POD), ascorbate peroxidase (APX), and catalase (CAT), in shoots and roots subjected to salt and dehydration stresses during seedling growth. After NaCl or PEG treatment, plants showed reduced seedling growth under over 200 mM NaCl or 30% PEG treatment condition in shoots and roots compared with the control condition. In addition, plants showed high enzymatic activity of CAT in the shoots, whereas they exhibited high activity levels of APX and POD in the roots in both the NaCl and PEG treatment conditions. These results seem to indicate that Leymus chinensis seedlings responding to salt and dehydration stresses during initial growth is associated with enhanced activity of $H_2O_2$ scavenging antioxidant enzymes in the shoots or roots. The plants also showed high levels of total phenolics under NaCl treatment, with a high concentration in both the shoots and roots. Our results showed that the induced activity patterns of APX in the roots and CAT in the shoots indicate that low $H_2O_2$ levels were mainly maintained through tissue-specific redox homeostasis involving enzymes such as APX and CAT during salt and dehydration stresses. This study highlights the importance of antioxidant enzymes in the establishment of Leymus chinensis seedlings under high salinity conditions, such as typical desertification.

• Korean Journal of Weed Science
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• v.30 no.2
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• pp.111-121
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• 2010

Differential tolerance to protoporphyrinogen oxidase (Protox)-inhibiting herbicides, oxyfluorfen was observed between leaf ages in squash. Physiological responses to oxyfluorfen, including leaf injury, cellular leakage, accumulation of tetrapyrroles, and antioxidative enzymes activity, were investigated in leaf age classes of squash to identify mechanisms of oxyfluorfen tolerance. Leaf 1, 2, and 3 injuries for Joongangaehobak were >10,000, 1,286, and 1.6-fold higher than that of leaf 4, after treatment of oxyfluorfen. On the other hand, leaf 1, 2, and 3 injuries for Sintowjahobak were 725, 366, and >0.6-fold higher than that of leaf 4, after treatment of oxyfluorfen. However, in contrast to oxyfluorfen treatment results, leaf injury of squash leaf 4 treated with paraquat was much smaller than in leaves 1, 2 and 3. Electrolyte leakage from the tissues treated with oxyfluorfen was higher in the youngest leaf (Leaf 4) than in the older leaves 1, 2, and 3. Differential leaf response to oxyfluorfen of squash appears to be due in large part to differences in protoporphyrin IX (Proto IX), Mg-Proto IX, and Mg-Proto IX monomethyl ester accumulation in treated leaves. In contrast, leaf 4 had higher activities of superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, and glutathione reductase than leaf 1 after treatment with oxyfluorfen. However, the induction in antioxidant activity in leaf 4 was not enough to overcome the toxic effects of a Protox inhibitor, oxyfluorfen, so the leaf eventually died.