• 한국미생물·생명공학회지
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• 제23권1호
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• pp.24-30
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• 1995

The effects of amino acids in growth media on the biosynthesis of Serratia marcescens biodegradative threonine dehydratase activity were examined. The enzyme activity was decreased by 44 and 34% by 10 mM isoleucine and valine, respectively, whereas it was increased approximately by 20% by 10 mM threonine. Among several metabolites tested, pyruvate increased the enzyme activity by 60% at 5 mM, but decreased the enzyme activity approximately by 20 to 70% above 20 mM. The enzyme activity was increased by 64% by 5 mM glyoxylate, whereas it decreased the enzyme activity approximately by 40 to 70% above 20 mM glyoxylate. The thiamine, monopyrrole derivative, also increased the enzyme activity by 84% at 50 $\mu $g/ml, but did not affected the enzyme activity above 300 $\mu $g/ml. cAMP increased the enzyme activity by 58% at 0.5 mM, but decreased the enzyme activity by 15% at 2 mM. These data suggested that the biosynthesis of Serratia marcescens biodegradative threonine dehydratase is regulated by concentrations of pyruvate, glyoxylate and cAMP.

• 한국식품영양과학회지
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• 제27권6호
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• pp.1105-1109
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• 1998

The superoxide dismutase(SOD) in peeled pericarp of cucumber was most stable at pH 8.0 and relatively stabe between pH 5.0 and 9.0. The enzyme was stable up to 6$0^{\circ}C$ and retained 12% by heat treatment at 10$0^{\circ}C$ for 5 min. At pH 2.0, the peeled pericarp enzyme activity was decreased to 10% by incubation for 3 hrs. However, the enzyme activity was increased above 25% after incubating the enzyme at pH 7.0 for 6 hrs. Retention of SOD activity in cucumber by various heating methods was also measured. The residual SOD activities of peeled pericarp and whole cucumber was estimated to be 25% and 27% after blanching(2 min), respectively. The skin enzyme retained 53% of its activity after steaming (3 min). When the peeled pericarp enzyme was incubated at 4$^{\circ}C$ for 20 days, the enzyme activity remained about 81%. However, when the enzyme incubated at 3$0^{\circ}C$ for 20 days, the peeled pericarp enzyme activity decreased to 17% of its original activity. The enzyme activity of peeled pericarp cucumber was not changed after exhaustive dialysis for 3 days, which indicated that the SOD activity in cucumber seems to have molecular weight above 12,000.

• 펄프종이기술
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• 제47권1호
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• pp.59-65
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• 2015

In this study, we evaluated optimum condition of enzyme with pH and temperature for preparation of microfibillated cellulose(MFC). Well-known endo-glucanase, three enzymes were used and CMC was used for substrate. Enzyme activity was evaluated using DNS method and absorbance with UV/VIS spectrophotometer. The enzyme shown the greatest activity was reacted with pulps at optimum condition for 1 hour and treated pulps beated until 100 mL CSF. Enzyme B and Enzyme L was the higher enzyme activity below 0.1% concentration and Enzyme N was the lowest enzyme activity. At various pH and temperature conditions, enzyme activity of Enzyme B was higher than the others at the same concentration. Especially enzyme activity at $50^{\circ}C$ of Enzyme B was almost not changed over pH 6.0. Optimum condition of three enzyme was pH 6 or pH 7 and $50^{\circ}C$ or $60^{\circ}C$. Also beating efficiency of enzyme treated pulps with Enzyme B is 55.6%.

• Journal of Plant Biotechnology
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• 제6권1호
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• pp.63-67
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• 2004

A simple procedure for the extraction of the lipolytic enzyme from rice bran has been developed. High activity of lipolytic enzyme was obtained by first defatting the rice bran to remove lipid components with various extraction conditions. Then, after rove cycles of aqueous extraction, rice bran lipolytic enzyme was purified using micro- and ultrafiltration apparatus. Lipolytic enzyme activity was estimated by its hydrolytic action of tributyrin. The result indicated that the standard activity curve of butyric acid showed that the potential rice bran enzyme is a hydrolytic lipase enzyme. In addition, it showed higher lipolytic activity and specific enzyme activity with further purification by micro- and ultrafiltration. The size of rice bran lipase enzyme was identified through 15 ％ SDS-PAGE. The molecular weight of the rice bran lipase enzyme was 41 kDa.

• 한국환경과학회지
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• 제8권1호
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• pp.19-26
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• 1999

The degree of pesticides accumulation in tap water in Taejon from June 1995 to Apr 1996 was measured by Ellman's coupled enzyme assay. Since organic phosphate and carbamate pesticides specifically inhibit the neurotransmitter modulating enzyme acetylcholinesterase(AChE), the enzyme activity can be used as a diagnosis for the pesticides accumulation in water and various samples. During the period of this study, the enzyme activity was changed almost every week. The lowest enzyme activity was 64 % of that of the control reaction and there are several days showing about 100 % enzyme activity. In general, the enzyme activity is higher in summer than other seasons especially early spring times. The pH value of tap water was very close to neutral(pH 7.0) and it seems that the enzyme activity was not affected by the small pH changes. Either boiling of tap water or addition of NaOH solution decomposed the pesticide components. These results show that AChE assay is a convenient, sensitive, and reliable method for detection of pesticides in water samples.

• 펄프종이기술
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• 제31권3호
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• pp.1-9
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• 1999

Effect of furnish on enzyme activity was investigated by using the three components (cellulose, enzyme, and cationic polyelectrolyte) model papermaking system. Avicel was used as a cellulose model compound to observe the effect of adsorption and desorption of enzyme with other component and the resultant change of particle size. As an experimental result, the enzyme loses considerably its apparent activity due to the adsorption onto cellulose and cationic polyelectrolyte. Activities of enzyme applied to the actual papermaking stocks having controlled fiber length showed different behavior in terms of pulp species UKP and KOCC stocks. That is, the enzyme activity in UKP was increased as fines content increased, however, vice versa in KOCC stock . This result can be considered to be the existence of various contaminants included in the fines of KOCC . The effect of possible contaminants such as inorganic materials, calcium ion, surfactant, and conductivity on enzyme activity were also investigated.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 추계학술대회
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• pp.299-301
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• 2004

A simple procedure for the extraction of the lipolytic enzyme from rice bran has been developed. High activity of lipolytic enzyme was obtained by first defatting the rice bran to remove lipid components with various extraction conditions. Then, after five cycles of aqueous extraction, rice bran lipolytic enzyme was purified using micro- and ultrafiltration apparatus. Lipolytic enzyme activity was estimated by its hydrolytic action of tributyrin. The result indicated that the standard activity curve of butyric acid showed that the potential rice bran enzyme is a hydrolytic lipase enzyme. In addition, it showed higher lipolytic activity and specific enzyme activity with further purification by micro- and ultrafiltration.

• 한국식품영양과학회지
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• 제24권4호
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• pp.563-569
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• 1995

Myrosinase from Korean cabbage(Bogdoli) was purified and its enzymatic properties were investigated. Myrosinase from the Korean cabbage was purified by DEAE Bio-Gel Sepharose, Concanavalin-A, and Mono-Q column chromatography and exhibited a 55KD molecular weight with a single band on the gel of SDS-PAGE. The enzyme was purified about 21-fold compared to its crude enzyme and a specific activity of purified enzyme was 15, 120units/mg. Optimum pH of the myrosinase was 7.0 in both phosphate and Tris-HCl buffer solutions, the enzyme was stable at pH 6.5~7.0. Optimum temperature of enzyme was 37~38$^{\circ}C$. The enzyme activity was significantly inhibited by Cu2+ and Hg2+, but enhanced by ascorbic acid, resulting in a maximum activity at 1mM ascorbic acid. Among the ascorbic acid analogues, dehydro-ascorbic acid did not affect, whereas others showed a little effect on the enzyme activity, but less than ascorbic acid itself. Reducing agents such as 2-mercaptoethanol and dithiothreitol had no effect on the enzyme activity, but the enzyme activity was enhanced when 2-mercaptoethanol was mixed with ascorbic acid.

• 한국미생물·생명공학회지
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• 제25권1호
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• pp.37-43
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• 1997

Triphenylmethane was decolorized rapidly by enterbacter cloacae MG 82 at initial reaction time. The spheroplast showed higher activity of triphenylmentane decolorization than that of intact cell suspension. The outer part of the bacterial cell envelope and the peptidoglycan are important for the function of transport barrier of triphenylmethane. In intact cell, decolorization activity was higher at 37$\circ $C than at $\circ $C, indicating that triphenylmethane decolorization is due to the enzyme reaction. Culture filtrate showed no decolorization activity, while cell-free extract appeared high activity of 1.45 units, clearly showing that decolorization activity was due to the cell-free extract. Comparing decolorization activities of cell fractions, it was found that decolorization activity was located at the compartment of cytoplasmic membrane. The enzyme activity was also shown to be Mg$^{++}$-dependent. The optimum pH and temperature of enzyme activity were 7.0 and 50$\circ $C, respectively. The thermostability of this enzyme at 35$\circ $C was kept to 58% for 3 hours.

• Journal of Nutrition and Health
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• 제27권9호
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• pp.892-900
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• 1994

A variety of important roles for branched-chain amino acids in metabolic regulation has been suggested. Branched-chain $\alpha$-keto acid dehydrogenase(BCKAD) complex is a rate limiting enzyme in branched-chain amino acid metabolism. The purpose of this study was to examine the effects of exercise on the activity and activity state of branched-chain $\alpha$-keto acid dehydrogenase in rat hert and liver thssues. Forty-eight Sprague-Dawley rats were assigned into three experimental groups : sedentary control, exercised, or exercised-rested. Submaximal exercise(running) for two hours significantly increased basal activity without a change in total activity in both tissues, with a concomitiant increase in activity state of the enzyme complex. At 10 min post-exercise, heart enzyme activity significantly decreased, though not to the control level, while liver enzyme activity remained unchanged. These data suggested that the exercise-induced increase in branched-chain $\alpha$-keto acid decarboxylation in rat tissues may not be the result of enzyme synthesis, but rather is due to increased activity of the BCKAD.