• Journal of the Korean Society of Food Science and Nutrition
• /
• v.20 no.3
• /
• pp.241-245
• /
• 1991

A polyphenol oxidase from the crude extract of Aster scaber was partially purified by (NH4)2 SO4 precipitation and subsequent Sephadex G-150 chromatography. The final preparation showed five peaks of enzyme activity. Optimum pH and temperature for the activity of polyphenol oxidase were 7.0 and $30^{\circ}C$, respectively. Enzyme activity was stable at $40^{\circ}C$ for 5min in pH 7.0 reaction mixture but ceased completely at $60^{\circ}C$ for 30min and $70^{\circ}C$ for 5min at pH 7.0. The olyphenol oxidase has good activity acid but was inactive on DL-depa. The apparent Km for catechol was about 17.6mM.

• BMB Reports
• /
• v.31 no.1
• /
• pp.70-76
• /
• 1998

The final step in ethylene biosynthesis is catalyzed by the enzyme 1-aminocyclopropane-1-carboxylate (ACC) oxidase. ACC oxidase was extracted from mung bean hypocotyls and its biochemical characteristics were determined. In vitro ACC oxidase activity required ascorbate and $Fe^{2+}$, and was enhanced by sodium bicarbonate. Maximum specific activity (approximately 20 nl ethylene $h^{-1}$ mg $protein^{-1}$) was obtained in an assay medium containing 100 mM MOPS (pH 7.5), $25\;{\mu}M$ $FeSO_4$, 6 mM sodium ascorbate, 1 mM ACC, 5 mM sodium bicarbonate and 10% glycerol. The apparent $K_m$ for ACC was $80{\pm}3\;{\mu}M$. Pretreating mung bean hypocotyls with ethylene increased in vitro ACC oxidase activity twofold. ACC oxidase activity was strongly inhibited by metal ions such as $Co^{2+}$, $Cu^{2+}$, $Zn^{2+}$, and $Mn^{2+}$, and by salicylic acid. Inactivation of ACC oxidase by salicylic acid could be overcome by increasing the $Fe^{2+}$ concentration of the assay medium. The possible mode of inhibition of ACC oxidase activity by salicylic acid is discussed.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.20 no.6
• /
• pp.527-537
• /
• 1991

To evaluate an effect of liver xanthine oxidase on the induction of liver damage, carbon tetrachloride (CCl4) was intraperitoneally injected twice at 0.1ml/100g body weight to the rate fed a low (LP)or high protein diet(HP) while the control group fed LP or HP received only olive oil. The changing rate of liver xanthine oxidas activity was compared with that of a free radical generating enzyme, liver aniline hydroxylase and a scavenging enzyme, glutathions S-transferase activity between the rate fed a LP and those fed HP, and the two groups treated with CCl4. Concomitantly, the degree of liver damage which could be considered as the paramete for CCl4 metabolism in case of CCl4-intoxicated animal was observed in the present experimental conditions and the effect of allopurinol, xanthine oxidase inhibitor, on the CCl4-toxicity of rate liver was alos demostrated. On the other hand, the comparative effect of actinomycin D on the liver and serum xanthine oxidase of CCl4-treated rats fed HP with that of those fed LP and the kinetics of purifed liver enzyme from the liver of CCl4-treated rats fed HP was also compared with that of those fed LP to clarify the differences of xanthine oxidase activity between two groups. The increasing rate of liver weigth/body wt, serum levels of ALT and the decreasing rate of hepatic ALT activity and protein contents to each control group were higher in CCl4-treated rats fed HP than those fed LP. Under the animal models as indentified by the present data herein, the liver xanthine oxidase activity was higher in CCl4-treated rats fed HP than those fed LP, and the control group fed HP also showed the much higher activity xanthine oxidase than that fed LP, whereas there were no differences in the activity of hepatic aniline hydroxylase and glutathions S-transferase between the two group treated with CCl4. Although the hepatic aniline hydroxylase activity was somewhat higher in the rats fed HP than those fed LP, the increasing rate of liver xanthine oxidase to the rats fed LP was higher in those fed HP than that of liver aniline hydroxylase. The degree of liver damage identified such as liver weight and serum ALT activity was less in the CCl4-treated rats pretreated with allopurinol. These results suggest that even a system at which xanthine oxidase acts as well as the drug metabolizing enzyme may influence the acelatin of CCl4 metabolism. In addition, the purified liver xanthine oxidase from CCl4-treated rats fed HP showed decreased Km value when compared to its control group. The Km value of liver xanthine oxidase of CCl4-treated rats fed LP showed a similar Km value with its control group. Furthermore, the decreasing rate of liver and serum xanthine oxidase acitivity in CCl4-treated rats pretreated with actinomycin D to the CCl4-treated rats was higher in rats fed HP than in those fed LP. These results suggest that the inductino of xanthine oxidase in CCl4-treated rats fed HP may be greater than in those fed LP.

• The Korean Journal of Food And Nutrition
• /
• v.14 no.2
• /
• pp.120-125
• /
• 2001

The inhibitory effects of xanthine oxidase by the methanol extract and the solvent fractions obtained from persimmon leaves were investigated. The inhibition ratio of xanthine oxidase was 78% by addition of 2.0mg/ml of the methanol extract. Among the solvent fractions, the ethylacetate fraction showed the strongest inhibitory effect against the xanthine oxidase, followed by the hexane fraction. The effect increased with addition of the ethylacetate fraction. At a concentration of 2.0mg/ml of the ethylacetate fraction, 65% of the enzyme activity decreased within 1.0 min of incubation with xanthine oxidase. But the activity of xanthine oxidise did not decrease significantly by the length of the incubation time.

• Toxicological Research
• /
• v.11 no.1
• /
• pp.43-49
• /
• 1995

The effects of metallothionein and cadmium ion on the hepatic aldehyde oxidase activity and brain lipid peroxidation were tested in vitro. The content of brain lipid peroxide at the condition of normal or $300{\mu}M$ Fe(II)-induced was remarkably reduced by the addition of metallothionein in the incubation mixture. The induced content of lipid peroxide by cadmium $(30{\mu}g/ml)$ ion was reduced by metallothionein $(100{\mu}g/ml)$. The activity of aldehyde oxidase was not affected by metallothionein, but cadmium ion $(8.38{\mu}g/ml)$ increased the activity of aldehyde oxidase about 80% compared to the control. The cadmium-induced activity of aldehyde oxidase was restored to the control level by metallothionein or penicillamine.

• Archives of Pharmacal Research
• /
• v.18 no.1
• /
• pp.56-59
• /
• 1995

The effect of ceruloplasmin or copper ion on hepatic xanthine oxidase activity and type conversion was investigated using rat liver in vitro. It was observed that ceruloplasmin increased xanthine oxidase type conversion depending on duration of its storage. Xanthine oxidase (type O) activity and type conversion in incubation mixture was increased by the addition of heated celuroplasmin in a temperature dependent manner. The type conversioin of xanthine oxidase induced by heated ceruloplasmin was retumed to normal by the tratment with DTT or penicillamine. The effect of copper ion on type conversion of xanthine oxidase was similar to that of heated ceruloplasmin.

• The Korean Journal of Physiology and Pharmacology
• /
• v.6 no.1
• /
• pp.15-19
• /
• 2002

The role of vascular NAD(P)H oxidase in subarachnoid hemorrhage (SAH)-induced vasospasm in the basilar artery was examined in a rat model. Arterial vasospasm characterized by increased wall thickness and decreased lumen size was observed at 5 to 7 days after $2^{nd}$ injection of blood into cisterna magna, and these changes were significantly ameliorated by pretreatment of diphenyleneiodonium $(DPI,\;25\;{\mu}l\;of\;100\;{\mu}M),$ an inhibitor of NAD(P)H oxidase. To determine the time course of changes in the vascular NAD(P)H oxidase activity, cerebral vasculature was isolated at different time intervals from 12 hrs to 14 days after injection of autologous blood. At 24 hrs after the second injection of blood, the NAD(P)H oxidase activity was markedly increased with an enhanced membrane translocation of p47phox, but by 48 hours both the enzyme activity and p47phox translocation regained normal values, and were remained unchanged up to 14 days after SAH. However, no significant changes in the expression of p22phox mRNA was observed throughout the experiments. These findings suggest that the activation of NAD(P)H oxidase by which assembly of the oxidase components enhanced and subsequent production of superoxide in the early stages of SAH might contribute to the delayed cerebral vasospasm in SAH rats.

• BMB Reports
• /
• v.29 no.2
• /
• pp.163-168
• /
• 1996

Glycosylated polyphenol oxidase was purified from potato tuber using ammonium sulfate fractionation, Sephadex G-100, and concanavalin A Sepharose column chromatography. Two or three types of polyphenol oxidase were separated on concanavalin A Sepharose. Type I and II polyphenol oxidases did not bind to concanavalin A Sepharose. Type I seemed to be an aggregated form of polyphenol oxidase. Type III polyphenol oxidase, which is presumed to be glycosylated because it was bound to concanavalin A Sepharose and eluted with $\alpha$-D-methyl glucopyranoside, was further purified by chromatography on Econo-Pac Q and Superose 12. Glycosylated polyphenol oxidase was purified 130-fold from the dissolved ammonium sulfate pellet resulting in about $6\;{\mu}g$ of the enzyme from 100 g of potato tuber periderm. The molecular weight of the glycosylated enzyme determined by SDS-polyacrylamide gel electrophoresis was about 64,000. Optimum temperature and pH of both II and type III potato polyphenol oxidases were $20^{\circ}C$ and pH 7.0, respectively. Glycosylated form of polyphenol oxidase (type III) preferred catechol to catechin as a substrate, whereas type II enzyme showed the reverse substrate preference.

• YAKHAK HOEJI
• /
• v.38 no.2
• /
• pp.211-217
• /
• 1994

Copper intoxication and disturbance of copper metabolism induced various oxygen-derived free radicals related damages. The effect of copper ion on xanthine oxidase activity and type conversion of the enzyme which is concerned to generation of reactive oxygen species, was investigated, It was observed that xanthine oxidase activity was increased by addition of copper ion in the reaction mixture in proportional to the concentration of the metal ion until $60\;{\mu}M$, while the enzyme activity was inhibited in higher concentration of copper treatment. On the other hand, xanthine dehydrogenase activity was inhibited by copper ion addition with concentration dependently. Preincubation of enzyme source with $30\;{\mu}M$ of copper ion, which concentration marked increased the xanthine oxidase activity, unchanged the enzyme activity and type conversion compare to control in vitro system. It was also observed that copper induced xanthine oxidase activity and the enzyme type conversion was protected by dithiothreitol and penicillamine. These results indicate that the increment of the type conversion of xanthine oxidase necessarilly need the presence of copper ion in enzyme assay system.

• Applied Biological Chemistry
• /
• v.21 no.3
• /
• pp.137-143
• /
• 1978

Xanthine oxidase from bovine thyroid glands was found to contain FAD, molybdenum and iron in a ratio 1:0. 36:1. 6. The molecular weight of the thyroid enzyme was similar to that of the milk enzyme when estimated by gel filtration and polyacrylamide gel electrophoresis. The optimum pH for the enzyme activity was 7.8. The pH of the isoelectric point was determined to be 6.2 by electrofocusing. Sodium dodecyl sulfatepolyacrylamide gel electrophoresis experiment indicated that the enzyme was dissociated into subunits and that the molecular weight for the smallest subunit was 65,000 daltons. Absorption spectra were dissimilar between milk and thyroid xanthine oxidase.