• Preventive Nutrition and Food Science
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• v.2 no.4
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• pp.354-359
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• 1997

Optimal cultivation conditions for the production of phenylalanine ammonia-lyase(PAL) from Rhodotorula aurantiaca K-505 were selected, and the kinetic parameters of the produced PAL were determined. The most suitable carbon and nitrogen sources were glucose and tryptone, respectively. The strain expressed PAL constituttively when using the optimized semi-complex media. High cell density culture could be critical for maximal production of PAl since the PAL ynthesis was growth associated. maximum PAL activity was observed at initial pH 6.0. although the ll growth was not markedly affected by temperature between 22 and 28$^{\circ}C$, the cells yielded the maximum PAL activity when cultivated at 22$^{\circ}C$. The maximum activity for deamination of L-phenylalnine to trans-cinnamic acid was observed around pH 8.8. The PAL activity gave the maximum at 45$^{\circ}C$, and greatly decreased at higher than 5$0^{\circ}C$. Activation energy({TEX}$E_{a}${/TEX}) calculated from Arrhenius equation was 6.28 kcal/mol in the range of 22$^{\circ}C$ to 4$0^{\circ}C$. A oolf plot showed that the enzyme reaction follows Michaelis-Menten equation, whose {TEX}$K_{M}${/TEX} and {TEX}$V_{max}${/TEX} values were 4.65$\times${TEX}$10^{-3}${/TEX} M and 0.89$\mu$ mol/mg-min respectively.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.649-656
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• 1992

The synthesis of epichlorohydrin was carried out by the epoxidation of allyl chloride with tert-butyl hydroperoxide(TBHP) over silica supported molybdenum catalyst. Kinetic study was performed at $60-80^{\circ}C$ and 10 atm with the molar ratio of TBHP/Allyl chloride between 0.01 and 0.1 in a batch reactor. The epoxidation of allyl chloride was inhibited by tert-butyl alcohol and kinetic data could be represented by Michaelis-Meten type rate equation. The reaction mechanism could be explained by the combination of reversible adsorption of TBHP and tert-butyl alcohol accompanied by reaction of allyl chloride with TBHP adsorbed on $Mo/SiO_2$ catalyst.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.5
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• pp.839-846
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• 2016

Since oil leakage is one of the most common nonpoint pollution sources that contaminate soil in Korea, the capacity of soil microbial community for degrading petroleum hydrocarbons should be considered to assess the functional value of soil resource. However, conventional methods (e.g., microcosm experiments) to assess the remediation capacity of soil microbial community are costly and time-consuming to cover large area. The present study suggests a new approach to assess the toluene remediation capacity of soil microbial community using a microbial diversity index, which is a simpler detection method than measuring degradation rate. The results showed that Shannon index of microbial community were correlated with specific degradation rate ($V_{max}$), a degradation factor. Subsequently, a correlation equation was generated and applied to Michaelis-Menten kinetics. These results will be useful to conveniently assess the remediation capacity of soil microbial community and can be widely applied to diverse engineering fields including environment-friendly construction engineering fields.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.3
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• pp.127-136
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• 1990

In this paper, the experimental study was carried out for the removal of olive oil in wastewater by the use of Biological Fluidized Bed(BFB) with the reticulated polypropylene sheets as media. The nonbiodegradable olive oil, one of the animal and vegitable oil, was used bacause of the relative simplicity of constitution. Biological degraciability and removal characteristics of emulsified olive oil were studied by batch and continuous experiments respectively. From the results of batch experiments, it was observed that the emulsified olive oli used in BFB reactor was absorbed by media and sludge in about 12 hours, and degradation of the absorbed olive oli was mostly completed for 24 hours. The functional relationship of Michaelis-Menten's Enzyme reaction equation exists between oil concentration and maximum specific rate of olive oil. From the continuous experiments for the removal of olive oil using BFB reactor, it was proved that the substrate removal rate coefficient $k=0.004d^{-1}$, which is the first order kinetics. It was apperared that oxygen utlization coefficients for synthesis(a') and endogeneous respiration(b') of microorganisms in the reactor are respectively 0.85mg $O_2/mg$ $COD_{cr}$ and 0.011mg $O_2/mg$ BVS. day.

• Journal of Preventive Medicine and Public Health
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• v.7 no.1
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• pp.107-113
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• 1974

Many factors exert an influence on enzyme activity and thus on the rate of reactions that they catalyse. The most important of these factors are pH, temperature, substrate concentration, and the concentration of some inhibitors present. A solution of the enzyme diastase, which breaks down molecules of the polysaccharide starch to the disaccharide maltose by hydrolysis, was provided. Activity of this enzyme was measured by the rate at which starch was removed from the reaction mixture. These experiments were designed to study this reaction rate under varying conditions and the following results were obtained. 1. The range of optimum pH for this enzyme at room temperature was 4.0-7.0 and the optimum pH was 5.0. 2. The range of optimum temperatures for this enzyme at pH 7.0 was $30^{\circ}C-50^{\circ}C$ and the optimum temperature was $40^{\circ}C$. 3. The relationship between the enzyme activity and substrate concentration could be expressed by the Michaelis-Menten equation. The limiting velocity of this enzyme at room temperature and pH 7.0 was $415{\mu}g$ starch removed/ml of reaction mixture/min and $K_m$, Michaelis constant, was $343{\mu}g/ml$. 4. Inhibitors NaCl and $HgCl_2$ blocked this enzyme activity completely at 1% and 0.01% respectively.

• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.385-390
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• 2002

Laccase could be successfully assembled on an amine-derivatized platinum electrode by glutaraldehyde coupling. The enzyme layer formed on the surface does not communicate electron directly with the electrode, but the enzymatic activity of the surf ace could be followed by electrochemical detection of enzymatically oxidized products. The well-known laccase substrates, ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)) and PPD (p-phenylenediamine) were used. ABTS can be detected down to 0.5 ${\mu}M$ with linear response up to 15 ${\mu}M$ and current sensitivity of 75 nA/ ${\mu}M.$ PPD showed better response with detection limit of 0.05 ${\mu}M$, linear response up to 20 ${\mu}M$, and current sensitivity of 340 nA/ ${\mu}M$ with the same electrode. The sensor responses fit well to the Michaelis-Menten equation and apparent $K_M$ values are 0.16 mM for ABTS and 0.055 mM for PPD, which show the enzymatic reaction is the rate-determining step. The laccase electrode we developed is very stable and more than 80% of initial activity was still maintained after 2 months of uses.

• Parasites, Hosts and Diseases
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• v.61 no.4
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• pp.428-438
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• 2023

Clonorchis sinensis is commonly found in East Asian countries. Clonorchiasis is prevalent in these countries and can lead to various clinical symptoms. In this study, we used overlap extension polymerase chain reaction (PCR) and the Xenopus laevis oocyte expression system to isolate a cDNA encoding the choline transporter of C. sinensis (CsChT). We subsequently characterized recombinant CsChT. Expression of CsChT in X. laevis oocytes enabled efficient transport of radiolabeled choline, with no detectable uptake of arginine, α-ketoglutarate, p-aminohippurate, taurocholate, and estrone sulfate. Influx and efflux experiments showed that CsChT-mediated choline uptake was time- and sodium-dependent, with no exchange properties. Concentration-dependent analyses of revealed saturable kinetics consistent with the Michaelis-Menten equation, while nonlinear regression analyses revealed a Km value of 8.3 µM and a Vmax of 61.0 pmol/oocyte/h. These findings contribute to widen our understanding of CsChT transport properties and the cascade of choline metabolisms within C. sinensis.

• Journal of Pharmaceutical Investigation
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• v.21 no.1
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• pp.43-50
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• 1991

The hepatic uptake of an anionic fluorescence probe, l-anilino-8-naphthalene sulfonate (ANS) was characterized using isolated rat hepatocytes. The initial uptake rate of ANS by isolated hepatocytes was determined. The uptake process of ANS was fitted well to the Michaelis-Menten equation with a saturable component. The $V_{max}$ and $K_m$ values were $2.9{\pm}0.1\;nmol/min/mg$ protein and $29.1{\pm}3.2\;{\mu}M$, respectively. The uptake clearance $(CL_{up})$ based on the ratio of $V_{max}$ to $K_m$ was 11.7 ml/min/g liver, revealing the good coincidence with that assessed from the analysis of the plasma disappearance curve in previous report. Furthermore, the effect of serum protein on the hepatic uptake of ANS into isolated hepatocytes was investigated. The permeability clearances $(PS_{inf})$ of ANS uptake were much higher than those predicted based on the unbound fractions in the presence of serum. These suggested that the hepatic uptake of extensively serum protein-bound ANS is mediated not only by the unbound form of ligand but also by the serum protein-mediated uptake mechanism.

• Archives of Pharmacal Research
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• v.26 no.4
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• pp.338-343
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• 2003

The purpose of the present study was to investigate the bidirectional transport of 1-anilino-8-naphthalene sulfonate (ANS) using isolated rat hepatocytes. The initial uptake rate of ANS by isolated hepatocytes was determined. The uptake process of ANS was saturable, with a $K_m of 29.1\pm3.2 \mu M and V_{max} of 2.9\pm0.1$ mmol/min/mg protein. Subsequently, the initial efflux rate of ANS from isolated hepatocytes was determined by resuspending preloaded cells to 3.0% (w/v) BSA buffer. The efflux process for total ANS revealed a little saturability. The mean value of the efflux clearance was $2.2\pm0.1 \mu$ L/min/mg protein. The efflux rate of ANS from hepatocytes was markedly decreased at $4^{\circ}C$, indicating that the apparent efflux of ANS might not be attributed to the release of ANS bound to the cell surface, but to the efflux of ANS from intracellular space. The efflux clearance was furthermore corrected for the unbound intracellular ANS concentration on the basis of its binding parameters to cytosol. The relation between efflux rate and unbound ANS concentration was fitted well to the Michaelis-Menten equation with a saturable and a nonsaturable components. The $V_{max} and K_m$ values were 0.54 mmol/min/mg protein, and 10.0 $\mu$ M, respectively. Based on the comparison of the ratios of $V_{max} to K_m (V_{max}/K_m)$ corresponding to the transport clearance, the influx clearance was two times higher than the efflux clearance. Together with our preliminary studies that ATP suppression in hepatocytes substantially inhibited ANS influx rate, we concluded that the hepatic uptake of ANS is actively taken up into hepatocytes via the carrier mediated transport system.

• Journal of Environmental Impact Assessment
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• v.9 no.1
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• pp.39-46
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• 2000

Removal of ammonia using the porous ceramic biofilter inoculated with earthworm casts was characterized. By assuming a plug air flow in the biofilter and applying the Michaelis-Menten equation, the maximum removal rate of $NH_3$ was $280.7g-N{\cdot}m^{-3}{\cdot}h^{-1}$($18.0g-N{\cdot}kg^{-1}{\cdot}d^{-1}$) at $30^{\circ}C$. $NH_3$ removal rate was increased as temperature increases from $15^{\circ}C$ to $35^{\circ}C$. The maximum removal rate was $285.8g-N{\cdot}m^{-3}{\cdot}h^{-1}$($18.8g-N{\cdot}kg^{-1}{\cdot}d^{-1}$) at $35^{\circ}C$. At $15^{\circ}C$, the $NH_3$ removal rate was $122.8g-N{\cdot}m^{-3}{\cdot}h^{-1}$($8.1g-N{\cdot}kg^{-1}{\cdot}d^{-1}$). When 210 ppm $NH_3$ was supplied to the biofilter at space velocity of $220h^{-1}$, the removal efficiency of $NH_3$ at 15, 25, 30 and $35^{\circ}C$ was 80, 90, 95, and 96%, respectively. The removal rate of the ceramic biofilter was 3 to 15 times higher than other biofilters comparing the removal efficiency of $NH_3$ per unit volume of carrier. This result indicates that earthworm casts and porous ceramics are very good inoculum source and carrier, respectively, for the $NH_3$-degrading biofilter.