• International Journal of Industrial Entomology and Biomaterials
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• v.12 no.1
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• pp.21-28
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• 2006

Peroxidase activity was measured in brown leaf spot pathogen (Myrothecium roridum) inoculated potted mulberry (Morus alba) during pre-symptomatic to various symptom development stages and compared with corresponding healthy leaf tissues. The enzyme showed a pH optimum of 7.0 and the activity was linearly increased up to 15 min of incubation. The peroxidase had a broad substrate specificity and the rates of oxidation were in the rank of pyrogallol> guaiacol> ascorbate at pH 7.0. Catechol at 10 mM inhibited 89% of guaiacol-peroxidase and 76% pyrogallol-peroxidase activities, indicated higher non-specific peroxidation in pyrogallol dependent assay system in mulberry than guaiacol. The optimum requirement for the guaiacol dependent assay was 0.2 ml (${\approx}40-60{\mu}g$ equivalent of protein) of crude enzyme source. Excepting the 8th leaf from the apex, the peroxidase activity did not vary appreciably in different leaf positions. In pre-symptomatic phases, an initial (1 to 5 min) rise of peroxidase activity was noticed in inoculated leaves, and then maintained a plateau up to 300 min. In contrary, non-infected tissue showed a slightly increased trend of enzyme level up to 420 min. In infected tissue, a sharp transient increase (3.1 fold) of peroxidase activity appeared between 300 - 420 min post infections. Afterwards, significantly different but steady maintenance of enzyme levels were observed in two treatments. On the other hand, during symptom development, a sharp increase in peroxidase activity was noticed up to 4th grade of lesion appearance (25.1 % to 50% of leaf area infection), and then declined slightly. However, in non-infected but same age healthy leaves, such huge fluctuations of enzyme level did not apparent. A high positive correlation $(R^2=0.92)$ between peroxidase activity and leaf spot development grades was also marked. The result implies that pre-symptomatic burst (between 1 - 5 and 300 - 420 min) and subsequent increased trend of guaiacol peroxidase activity may require for the symptomatic manifestation of Myrothecium leaf spot in mulberry.

• Journal of Microbiology and Biotechnology
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• v.17 no.4
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• pp.600-603
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• 2007

The effect of a water-miscible ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate $([BMIM][BF_4])$, on the horseradish peroxidase (HRP)-catalyzed oxidation of 2-methoxyphenol (guaiacol) with hydrogen peroxide $(H_2O_2)$ was investigated. HRP maintains its high activity in the aqueous mixtures containing various concentrations of the ionic liquid and even in 90% (v/v) ionic liquid. In order to minimize the effect of solution viscosity on the kinetic constants of HRP catalysis, the enzymatic reactions in the subsequent kinetic study were performed in water-ionic liquid mixtures containing 25% (v/v) ionic liquid at maximum. As the concentration of $[BMIM][BF_4]$ increased for the oxidation of guaiacol by HRP, the $K_m$ value increased with a slight decrease in the $K_{cat}$ value: The $K_m$ value increased from 2.8 mM in 100% (v/v) water to 22.5mM in 25% (v/v) ionic liquid, indicating that ionic liquid significantly weakens the binding affinity of guaiacol to HRP.

• Proceedings of the Zoological Society Korea Conference
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• 1996.10a
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• pp.182.2-182
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• 1996

• Applied Biological Chemistry
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• v.30 no.3
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• pp.219-226
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• 1987

Peroxidase isozyme C was isolated from mung bean cotyledon and purified to homogeneity as ascertained by chromatography and polyacrylamide gel electrophoresis, and then crystallized. Purification procedures included ammonium sulfate precipitation and column chromatography on Sephadex G-75, DEAE-cellulose and DEAE-Sephadex A-50. Peroxidase isozyme C was purified about 63 fold with 5% recovery. Isozyme C showed optimal activity at pH 5.0 with o-dianisidine and at pH 6.0 with guaiacol as substrate, and the optimal temperature was $70^{\circ}C$. Molecular weight of 50,000 was estimated for the isozyme C by SDS-polyacrylamide gel electrophoresis. At $70^{\circ}C$, it took 30 min to inactivate the isozyme to 50%, and at $80^{\circ}C$, this isozyme was almost completely inactivated in 20 min. The Km value of isozyme C for o-dianisidine was 0.11mM and that for guaiacol was 60.98mM using hydrogen peroxide as cosubstrate, and the kinetic pattern showed a competitive cyanide inhibition with respect to substrate. The crystalline structure of isozyme C was rectangular in shape.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.6
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• pp.1143-1147
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• 1998

Enzymatic characterization of peroxidase(E.C. 1.11.1.7) from soybean sprouts was investigated. The optimum pH of the purified peroxidase was 7.0 and relatively stable at pH 6.0~7.0. And the optimum temperature was 50oC. The enzyme was most active with guaiacol as a substrate, followed by (＋)catechin, pyrogallol and p phenylenediamine. The Km values for guaiacol and H2O2 were 4.2mM and 2.5mM, respectively. L Ascorbic acid and 2 mercaptoethanol greatly inhibited the enzyme activity, while Cu2+, Co2+ and Ni2+ activated the enzyme.

• Horticultural Science & Technology
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• v.18 no.6
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• pp.783-786
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• 2000

This study was carried out to examine the effect of root-zone temperatures on seedling growth, mineral contents and antioxidative enzyme activities of grafted watermelon. The grafted watermelon seedlings were grown in greenhouse bed for 20 days at root-zone day temperatures of 10, 15, $25^{\circ}C$ while night temperature was maintained at $10^{\circ}C$. Growth such as shoot height, leaf length, leaf number, stem diameter, and fresh and dry weights increased as increasing root-zone temperatures, and leaf area with $25^{\circ}C$($52.79mm^2$) was two times that of control($21.50mm^2$). As increasing the root-zone temperatures, Mn, Ca, Fe contents increased, K, P, Mg were non significant, and Na decreased. The activities of ascorbate peroxidase(APX) and guaiacol peroxidase(GPX) known as antioxidative enzyme were higher at $10^{\circ}C$ than $25^{\circ}C$.

• Journal of Life Science
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• v.8 no.4
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• pp.416-420
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• 1998

Soybean sprouts peroxidase can be used for enzymatic determination of glucose. Peroxidase from soybean sprouts was purified by ammonium sulfate precipitation and DEAE Sephacel column chromatography. The glucose could be quantitatively assayed by using glucose oxidase and soybean sprouts peroxidase. The optimum pH and temperature for glucose assay were of pH 5.5 and $40^{\circ}C$, respectively. The relationship between absorbance and glucose concentration was linear. And also the relationship between absorbance and reaction time was linear. The reducing agents such as L-cysteine, dithiothreitol inhibited the glucose assay by glucose oxidase and soybean sprouts peroxidase.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.4
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• pp.416-423
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• 2013

Germination is controlled by internal factors of seeds and external factors such as water, temperature and light. We investigated the relationship between germination characteristics of four waxy rice cultivars and patterns of water uptake, antioxidant enzymes and free soluble sugars during early imbibition. Seed viabilities by tetrazolium test of four different rice cultivars were higher than 95% and germination rates of the hulled rice seeds were on 95% average. However, germination rate of intact rice among four cultivars showed a big difference depending on temperature. Water uptake of hulled and intact rice seeds during imbibition reached a stationary phase at around 30% moisture content. Although rates of water uptake were faster in hulled rice and high temperature than intact rice and low temperature condition, difference of those among cultivars was greater under low temperature than high temperature. The time required for rice seeds to uptake 30% water was negatively correlated with percentage of germination, germination energy, germination speed and mean germination time. Guaiacol peroxidase activity at 24h of imbibition was correlated with germination energy and germination speed but not percentage of germination. Catalase activity, soluble protein and maltose concentration at 24h of imbibition were not correlated with characteristics of germination. These results suggest that a time required for rice seeds to uptake 30% of water significantly correlated with germination and guaiacol peroxidase activity during early imbibition plays an important role in initiation of germination.

• YAKHAK HOEJI
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• v.43 no.3
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• pp.334-341
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• 1999

Thyroid peroxidase is a biochemical target protein for the antithyroid drugs. Ethanol extracts from one hundred and thirty seven natural products were screened for the inhibition of thyroid peroxidase activity. Thyroid peroxidase was purified from porcine thyroids, and the inhibition of peroxidase activity was evaluated using guaiacol oxidation (C-C coupling) assay. Twenty one natural products expressed a remarkable inhibition (>50%) of peroxidase activity at $330{\mu\textrm{g}}$ solid weight/m. The 50% inhibitory concentration ($IC_{50}$) of 70% ethanol extract from six potent natural products ranged from 3.1 to $31.2{\;}{\mu\textrm{g}}$ solid weight/m, in contrast to the range ($0.33~0.54{\;}{\mu\textrm{g}}/ml$) of $IC_{50}$ values fro catechin and epigallocatechin gallate as positive controls. Noteworthy, the extract of Camellia taliensis showed irreversible inhibition of the enzyme. It is suggested that extract from some natural products such as Camellia taliensis, Rheum undulatum or Euphorbia perinensis, exhibiting a potent inhibition of peroxidase activity, may be developed as sources of potent antithyroid agents.

• Applied Biological Chemistry
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• v.43 no.2
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• pp.100-105
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• 2000

Anionic peroxidases (POD) were isolated from Korean radish (Raphanus sativus L.) root by using fractionation with $(NH_4)_2SO_4$ and CM-cellulose ion exchange chromatography and used as the colorimetric enzyme for glucose determination. The chromogen used in this work was o-tolidine or 4-aminoantipyrine/diethylaniline (4AA/DEA) and the colored products were measured at 630 nm. Korean radish anionic POD showed much better colorimetric reaction of glucose determination with 4AA/DEA than with o-tolidine. The r values of calibration curve for glucose determination by o-tolidine and 4AA/DEA were 0.9983 and 0.9963, respectively. In order to compare the reactivity for substrate oxidation by Korean radish POD and horseradish POD, the Km values against o-dianisidine and guaiacol were measured. Korean radish POD had about 40 fold higher affinity for o-dianisidine and 2 fold higher affinity for guaiacol as revealed by Km values. These results showed that Korean radish POD could be developed as the colorimetric diagnosis reagent for glucose determination with high sensitivity.