• Microbiology and Biotechnology Letters
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• v.21 no.4
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• pp.329-335
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• 1993

Ascorbate oxidase activity in various cucumber tissue extracts was highest in young fruit peeling. Cucumber callus was induced from young fruit peeling and callus cell lines were selected for more than 7 months, which porduced high levels of ascorbate oxidase and had a high growth rate. Induction of callus was optimized with Linsmaier-Skoog(LS) medium at 25$^{\circ}C$ in dark phase. Ascorbate oxidase activity reached a maximum at 5 days after transfer to LS basal liquid-medium ant then declined. The enzyme activity in callus cells was stimulated by addition of 10${\mu}$M $CuSO_4$ in the early logarithmic phase of growth. And also, adding 10${\mu}$M $CuSO_4$ at 3rd day 7th day of culture period, ascorbate oxidase activity in callus cells was maintained to high level. Maximum yield of ascorbate oxidase was found at the 25th day by flask shaking culture, but three-fold of ascorbate oxidase activity was obtained at the 16th day by jar fermentation.

• Korean Journal of Microbiology
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• v.26 no.1
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• pp.44-51
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• 1988

The intracellular free radicals produced at different stages of cell cycle of Saccharomyces cerevisiae ATCC 24858 were investigated by means of electron spin resonance(ESR) spectroscopy. The synchronized cells by repeated starvation and refeeding revealed different ESR spectral pattern compared to that of asynchronized cells. Each spectrum centered at g=2.005, which indicates free radicals. The relative spin concentration was maximat at the end of DNA increase. The variation of the relative spin concentration at each distinct stage of the cell cycle was evaluated in relation to ascorbate concentration, L-galactonolactone oxidase activity, and ascorbate oxidase activity. The highest activities of L-galactonolactone oxidase and ascorbate oxidase were detected just before and at the maximum of relative spin concentration, respectively. And ascorbate concentration fluctuated through each stage of cell cycle with the changes of relative spin concentration, L-galactonolactone oxidase activity, and ascorbate oxidase activity. Thus it is suggested that intracellular free radicals should be related to cell cycle, interacted with ascorbate, and may play an important role in the cell cycle of Saccharomyces cerevisiae.

• Korean Journal of Microbiology
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• v.26 no.2
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• pp.137-142
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• 1988

pH decreased as the substrate mycelium developed, $\Delta$pH was 1.05-1.15, but increased after the aerial mycelium formation. The lactic acid content in culture solution showed no difference between 0.2% and 5% glucose, at which the aerial mycelium formation was repressed. The growth and development of mycelium was delayed by the lactate treatment. The activity of catalase was maximum in 24 hours after inoculation, and the wuperoxide dismutase activity showed a constant level during the developmental phases. The ascorbic acid accumulated after the aerial mycelium formation. The ascorbate oxidase isozyme of Rf 0.44 appeared, while the isozyme of Rf 0.36 desappeared during the development.

• Journal of Ginseng Research
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• v.15 no.2
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• pp.139-143
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• 1991

This study investigated the relations between the photosynthetic rate and the activities of antioxidatile enzymes, glutathione reductase, ascorbate free radical reductase, ascorbate peroxidase, glutathione peroxidase, and ascorbate oxidase, in the leaves of Panax ginseng. Under the normal cultivation condition, Panax in showed lower g1utathione reductase and ascorbate free radical reductase activities the Glycine max. But P ginseng showed higher 91utathione Peroxidase, ascorbate Peroxidase, and ascorbate oxidase activities than C. Panax. Therefore, P. ginseng showed weak activities of reductases for the reduction of the oxidized antioxidants. Under the light intensity of 25 KLux, the reductases showed a decrease of over 75% after 24 hours. But the peroyoxidases decreased about 40%. These results showed that the decrease of reductases acitivities was consistent with the decrease of photosynthetic rate. Therefore, we consider that the regulation of antioxidative enzymes or the application of exogenous antioxidants will be effective means for the protection of photodamage in p. ginseng.

• Korean Journal of Microbiology
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• v.30 no.3
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• pp.225-231
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• 1992

l o identil) ;~nclc li~iracterize; In iiscorhate oxiililinp enzyme in ('/rItrn~i~rlon~ir~c~t~itr~~lr.o\ r(1rii. we studicil ;is li)llows. Ascorh;ric oxiiliring cn/;jme activit) f ~ o ~thne crude extract 01' ( ' / ~ l o n ~ ~ . c l o t ~1~~oit~rl~1oin~/.t\ii W;I\ dctccietl by 5pecific active 5ta1ning through nati\e gel cletrophorcsi\ and ~iltra\~iolestp eciroscopy. Ascorb~ttco xidizing c n ~ y m ew i15 partilly 1~1rilieJ by \;~riousp roccclurcs inclucli~lga rnmoniu~ns uIl';~tcp recipit;iion. aJ\orption ~111-om;~togrophy on Iiy~lroxyapaiitca nd Scphailcx <;-I50 gel lillration chrornatogral>liy. Plie ~nolecularw eight 01' the nativc cnrytiic was ahour 88.000 tlalton hy nativc gel elcciroplloresis anci subunit niolecul;ir ~rciglit 55,000 ol' this cnrymc w;~c determined hy SIIS-P.ASI!. The optimum tcmper~tture ii)r the cnrymc nos ahout 5j$^{\circ}$C and pH 4.6 was the optimum. Moreover. ascorhaie oxi~losc in C: reinhardtii was confirmet1 by Ll1e\tcrn blotting technique.

• Analytical Science and Technology
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• v.7 no.2
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• pp.149-153
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• 1994

An amperometric sensor for L-ascorbic acid(AA) in methanol media has been made by immobilizing squash-tissues on a graphite rod disk. A detection limit of the electrode was $2{\times}10^{-6}M$ L-ascorbic acid. In comparison with an isolated enzyme based ascorbate oxidase(AO) electrode, the plant-tissue electrode offered high biocatalytic stability and activity and extremely low cost. The electrode has a useful lifetime of 1 week.

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

• Analytical Science and Technology
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• v.8 no.4
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• pp.591-596
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• 1995

Enzyme multilayers composed of avidin and biotin-labeled enzymes were prepared on the surface of electrode, through a strong affinity between avidin and biotin (binding constant: ca $10^{15} M^{-1}$). The enzyme multilayers were useful for the improvement of the performance characteristies of enzyme sensors. The output current of the enzyme sensors depended linearly on the number of enzyme layers deposited. Thus, lactate oxidase (LOx) and alcohol oxidase (AlOx) were deposited after being modified with biotin for constructing enzyme sensors sensitive to L-lactate and ethanol respectively. It was also possible to deposit two different kinds of enzymes successively in a single multilayer. The glucose oxidase (GOx) and ascorbate oxidase (AsOx) were built into a multilayer structure on a Platinum electrode. The GOx, AsOx multilayer-modified electrode was useful for the elimination of ascorbic acid interference of the glucose sensor.

• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.247-252
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• 1999

The oxygen electrode of a biosensor needs enzyme immobilized membrane and a dialysis membrane to measure the oxygen concentration that remains after an enzyme reacts with its substrate. Accodingly, a single-layer PVA laminated CTA/PCL membrane was developed as an oxygen biosensor electrode. The enzymes were immobilized on a cellulose triacetate/polycarprolactone membrane using the 1,1'-carbonyl diimidazole(CDI) method, and then laminated with polyvinyl alcohol, aldehyde and acid. The alcohol oxidase and PVA laminated CTA/PCL membrane was tested with various concentration of enzyme substrates using a Yellow Springs Instrument(YSI) oxygen sensor. Under 5-10mmol substrates produced $0.37{\sim}0.83{\mu}A$(r=0.995) currents, and ater 8 weeks the glucose oxidase activity remained at about 56%, while the other activities remained very low. A SEM indicated a smooth surface and tightly attached PVA on the enzyme-immobilized CTA/PCL membranes.

• Korean Journal of Microbiology
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• v.8 no.2
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• pp.65-68
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• 1970

In continuation of the previous work (The New Medical Journal, Vol. 12, No. 3, 111, 1969), the effects on the bactericidal activity against coli form group, on vitamin C content and ascorbate oxidase activity of the purple laver due to the $^{80}Co$ gamma-irradiation were studied. The results obtained are ; 1) After the 0.1m rad./hr. doses treatment of gamma-irradiation for 1 hours to the laver, the coli form group was being remarkably destoryed and after the application for 10 hours the coli form group was completely destroyed. 2) The content of vitamin C was gradually decreased during the gamma-irradiation to the laver. According to the sensory test, no changes in flavor nad color were indicated for 9-10 hours treatment. But, the loss of ascorbic was much than that of dehydroascorbic acid after 10-hour treatment. 3) And also, the ascorbate oxidase activity due to the irradiation waas conspicuously decreased.