• Korean Journal of Food Science and Technology
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• v.30 no.2
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• pp.278-282
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• 1998

Peeled garlic, soybean sprouts, cut onion and cut green pepper were treated by dipping in solutions of different antibrowning agents, and then stored at $10^{\circ}C$. Surface color and polyphenol oxidase activity of produce were measured through the storage. Tested antibrowning agents include ascorbic acid, citric acid and allyl isothiocyanate. The commodities showed different responses to the antibrowning agent solutions; 1% citric acid for peeled garlic, 1% ascorbic acid for soybean sprouts, 2% citric acid for cut onion, and 1% ascorbic acid for cut green pepper showed better retardation in browning than the other treatments for respective product. For peeled garlic, surface browning was concomitant with increase in polyphenol oxidase activity during storage. On the other hand, there was no positive correlation between surface browning and polyphenol oxidase activity for the other stored products.

• The Korean Journal of Mycology
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• v.14 no.1
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• pp.43-47
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• 1986

Among the representative phenolic compounds in relation to lignin derivatives and protein synthesis inhibitors, the most effective inducer for the extracellular polyphenol oxidase (PO) of Lentinus edodes JA01 was gallic acid and ferulic acid for Pleurotus ostreatus. Optimum concentration of these inducers was 2.0 mM and 1.0 mM, respectively. Addition of gallic acid after two days culture had the best effect on production of PO enzyme of L. edodes JA01 and for P. ostreatus, and addition of ferulic acid after three days culture had the best effect. Also, in case of L. edodes JA01, polyphenol oxidase activity was parallel to growth curve, whereas the maximum enzyme activity of P. ostreatus was shown at exponential growth phase and declined thereafter.

• Applied Biological Chemistry
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• v.31 no.4
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• pp.331-338
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• 1988

Acetone powder was prepared from raw arrowroots and the polyphenol oxidases of crude enzyme prepared from acetone powder were identified 5 isoenzymes by staining with catechol containing 0.05% phenylene diamine. The crude enzyme was passed through the columns of ion exchangers and gel permeation to fractionate the polyphenol oxidases. The main fraction of polyphenol oxidase appeared to be purified by 94-fold, with the activity yield of 45.4%, and its molecular weight was determined as 38,500 by poly acrylamide gel electrophoresis. The optimal pH and temperature for the enzyme activity were pH 7.5 and $50^{\circ}C$, respectively. The purified enzyme showed a high affinity for catechol and pyrogallol. The Michaelis constant for catechol was calculated to be 16.67mM according to the Lineweaver-Burk method. The enzyme activity was strongly inhibited by L-ascorbic acid, sodium bisulfite, EDTA and KCN, and totally inhibited, by $Fe^{3+}$ at a concentration of 1mM. However the enzyme was activated by $Zn^{2+}$ approximately 1.7 times at the same concentration.

• Korean journal of food and cookery science
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• v.10 no.4
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• pp.339-345
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• 1994

Polyphenol oxidase in Yam was partially purified through ammonium sulfate fractionation, DEAE-cellulose column chromatography. The specific activity of purified PPO was 138.22 unit/mg protein. The optimum pH and temperature of purified PPO were respectively 7.0 and 30$^{\circ}C$. The heat treatment at 80$^{\circ}C$ for 6 min, decreased PPO activity to 50%. The enzyme showed high substrate specificity toward catechol. The Km value for catechol was 5 mM. In the Ames test using S. typhimurium TA98 and TA100 catechol-YEBRP, pyrogallol-YEBRP, chlorogenic-YEBRP showed strong antimutagenicity on sodium azide and MECF excepting hydroquinone-YEBRP showed killing effect on both strains.

• Journal of Ginseng Research
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• v.37 no.1
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• pp.117-123
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• 2013

Polyphenol oxidase (PPO) was purified from fresh ginseng roots using acetone precipitation, carboxymethyl (CM)-Sepharose chromatography, and phenyl-Sepharose chromatography. Two isoenzymes (PPO 1 and PPO 2) were separated using an ion-exchange column with CM-Sepharose. PPO 1 was purified up to 13.2-fold with a 22.6% yield. PPO 2 bound to CM-Sepharose, eluted with NaCl, and was purified up to 22.5-fold with a 17.4% yield. PPO 2 was further chromatographed on phenyl-Sepharose. The molecular weight of the purified PPO 2 from fresh ginseng was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was about 40 kDa. The optimum temperature and pH were $20^{\circ}C$ and 7.0, respectively, using catechol as a substrate. Pyrogallol showed the highest substrate specificity. The effect of a PPO inhibitor showed that its activity increased slightly in the presence of a low concentration of citric acid. High concentrations of acidic compounds and sulfite agents significantly inhibited purified ginseng PPO 2.

• YAKHAK HOEJI
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• v.40 no.1
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• pp.65-71
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• 1996

Characterization of Polyphenol oxidase (PPO) in Perillae Folium, particullarly inhibitor studies were investigated. This enzyme was stable at pH 5.0 and the residual activity of PPO at ${\geq}$ ph 5.5 was estimated to be very low. PPO activity was decreased slightly by adding amino acid with catechol as a substrate, particullary PPO activity was inhibited markedly by cystein, histidine, lysine and arginine. In the absorption spectra of the product formed when catechol was oxidized by PPO, with a ${\lambda}_{max}$ at 410nm, the peak shifted toward ${\lambda}_{max}$ 520nm by addition of L-proline. At relatively low concentrations($10^{-3}M$), sulfite and dithiothreithol completely inhibited PPO activity. Inhibition of PPO activity by amino acids and inhibitors increased or decreased depending on the pH used to measure it.

• YAKHAK HOEJI
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• v.45 no.4
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• pp.387-396
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• 2001

The effects of ascorbic acid, thiols such as cysteine, n-acetyl-ι-cyteine, glutathione, thiourea, 2-mercaptoethanol and dithiotreithol and organic acids such as magic acid, citric acid, glycolic acid, taurine and kojic acid on polyphenol oxidate (PPO) activity were studied in order to establish if it reacts with oxidized product and/or directly inhibits the enzyme. To investigate the mechanism, the quantification of t-butylcatechol and 4-methylcatechol (phenolic compounds) as substates, their oxidized product and sulphydryl colorless additional compounds were determined by high performance liquid chromatograph (HPLC) method. Chromatographic results indicate that ascorbic acid, organic acids and lower level of cysteine reduced oxidized product of substrates back to their respective positions uf ο-diphenols. On the other hand, other thiols and high level of cysteine reacted with oxidative product of ο-diphenols and then produced sulphydryl colorless compounds. Cysteine apperars to have two types of mechanism of actions in the formation of oxidative products of substrates depending on its concentration; ascorbic acid-type and other thiols-types. The effect of ascorbic acid with thiols on polyphenol oxidase was determined by same method. Chromatographic results indicate that ascorbic acid was more reactive with oxidized product of substrates than thiols.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.7
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• pp.955-959
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• 2006

Effects of chlorine dioxide ($ClO_2$) on weight loss, polyphenol oxidase activity, and microbial change of fresh mushrooms (Agricus bisporus Sing) were investigated. Mushrooms were treated with 5, 10, and 50 ppm of $ClO_2$ solution. Mushrooms were stored at room temperature and $4^{\circ}C$. Weight loss for $ClO_2$ treated mushrooms was smaller than that of the control group. Polyphenol oxidase activity of the $ClO_2-treated$ samples stored at room temperature increased until day 2 of storage and then decreased, and the activity of the samples stored bacteria, yeast and mold counts than the control during storage. Aerobic bacterial counts for 50 ppm of $ClO_2$ treatment at $4^{\circ}C$ increased from $1.62{\times}10^2\;CFU/g\;to\;1.66{\times}10^7\;CFU/g$ at day 10 of storage, while control groups were from $1.00{\times}10^3\;CFU/g\;to\;3.72{\times}10^8\;CFU/g$. These results indicate that $ClO_2$ treatment could be useful in improving the quality and microbial safety of mushrooms.

• Korean Journal of Pharmacognosy
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• v.15 no.2
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• pp.78-84
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• 1984

Polyphenol oxidase was purified from acetone powder extract of the root of Ixeris sonchifolia. The enzyme obtained by ammonium sulfate fractionation and sephadex G-200 gelfiltration gave 51-fold purification over the crude extract. The purified enzyme showed activity toward chlorogenic acid, caffeic acid and pyrocatechol. The kinetics of thermal inactivation of the enzyme followed first-order reaction. Potassium cyanide and cysteine were potent inhibitors.

• Korean Journal of Pharmacognosy
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• v.22 no.2
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• pp.101-111
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• 1991

Polyphenol oxidase(PPO) was purified from an extract of Puerariae Radix by ammonium sulfate fractionation followed by Sephadex G-150 column chromatography, which resulted in a 56-fold increase in specific activity. The enzyme was optimum of pH 6.5. The optimum temperature of enzymic reaction was about $40^{\circ}$. The enzyme was thermostable with a half-life equal to 32 min at $70^{\circ}$. Km values of the PPO for catechol and pyrogallol from Lineweaver Burk plots were $1.3{\times}10^{-2}M$, $1.16{\times}10^{-2}M$, respectively. The substrate specificity of the Puerariae Radix PPO showed high affinity toward pyrogallol. Reducing reagents such as cysteine, potassium metabisulfite, ascorbic acid, 2-mercaptoethanol completely inhibited the PPO activity at $10^{-2}M$ level. Linewear-Burk analysis of inhibition data revealed that the inhibition by cysteine, 2-mercaptoethanol, 4-nitrocatechol, potassium cyanide was competitive with Ki values of $4.3{\times10^{-2}M,\;0.73{\times}10^{-6}M,\;6.9{\times}10^{-6}M,\;6.4{\times}10^{-7}M$, respectively. The browning reaction by PPO was observed to decrease temporarily with the addition of sodium diethyl dithiocarbamate, a well known copper chelating agent. Among the divalent cations, $Cu^{2+}$ ion was strong activator on PPO and $Mn^{2+},\;Co^{2+}$ ions was effect on PPO activity. $Zn^{2+},\;Mg^{2+}$ ions was inhibitor on PPO.