• Food Engineering Progress
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• v.13 no.4
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• pp.251-261
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• 2009

In vitro physiological functions such as jack bean (Canavalia ensiformis) urease inhibitory activity and retarding effect of glucose/bile acid of Aloe vera gel concentrated by the optimized DIS (Dewatering Impregnation & Soaking) process conditions were examined. Urease inhibitory activity of DIS aloes ranged from 84.6 to 94.4%, which was similar to or higher than 86.3% of fresh aloe. Also, urease inhibitory activity of DIS aloes was maintained at initial levels after heat treatment (90$^{\circ}C$, 10 min.) and drying treatment (freeze or hot air drying). Urease inhibition pattern from Lineweaver-Burk plot indicated general non-competitive inhibition, and inhibition constants ($K_{IE}$ and $K_{IES}$) of DIS aloes were 41-149 and 87-163 $\mu$L/mL, respectively. DIS(glucose) and DIS(polyethylene glycol) exhibited the highest retarding effect of glucose and bile acid. Their retarding effects were about 1.6 and 1.8 folds higher than that of fresh aloe after 0.5 and 1 hr of the dialysis, respectively. Conclusively, the above in vitro physiological functions of Aloe vera gel concentrated by DIS process suggested that aloe products treated with DIS would have the potential benefits for protection against Helicobacter pylori and reduction of blood glucose and cholesterol levels.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.1
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• pp.62-68
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• 2013

The effect of organic substance on its degradation rate in burial site was investigated using batch tests. Substrate were swine and cattle with the initial concentrations of 2, 4, 6, 8, and 10 g VS(volatile solids)/L, respectively. The highest methane production rates of swine and cattle were found at 2 g VS/L as 46.3 and 48.4 ml CH4/g VS.d, respectively. As substrate concentration increased, the methane production rate decreased. The inhibition constants were n and m that were estimated using nonlinear inhibition model. The values of n and m were inhibition constants of methane production rate and ultimate methane yield, respectively. The values of n and m were 4.9 and 0.6 on swine and 1.1 and 0.4 on cattle. The methane production rate was responded sensitively by increase and decrease of substrate concentration, whereas ultimate methane yield do not relatively. From a relation between n and m, inhibitory effect of substrate concentration was confirmed as uncompetitive inhibition.

• Archives of Pharmacal Research
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• v.9 no.2
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• pp.81-86
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• 1986

The effect of imperatorin on hepatic microsomal mixed function oxidases (MF0) was investigated. On acute treatment, imperatorin (30 mg/kg, i.p) caused a significant reduction in activities of hepatic aminopyrine N-demethylase, hexobarbital hydroxylase and aniline hydroxylase as well as cytochrome p0450 content in rats and mice. Kinetic studies on rat liver enzymes revealed that imperatorin appeared to be a competitive inhibitor of aminopyrine N-demethylase (Ki,0.007 mM), whereas a non-competitive inhibitor of hexobarbital hydroxylase (Ki, 0.0148 mM). Imperatorin also inhibited non-competitively aniline metabolism (Ki 0.2 mM). Imperatorin binds to phenobarbital-induced cytochrome p-450 to give a typical type 1 binding sepctrum (max. 388nm, min 422 nm). Multiple administrations of imperatorin (30 mg/kg. i. p. daily for 7 days) to mice shortended markedly the duration of hexobarbital narcosis and increased activities of hepatic aminopyrine N-demethylase and hexobarbital hydroxylase and the level of cytochrome p-450 where as aniline hydroxylase activity was unaffected.

• Journal of Pharmaceutical Investigation
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• v.26 no.3
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• pp.175-185
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• 1996

To inhibit the enzymatic degradation of leucine enkephalin (Leu-Enk) and its synthetic analog. $[D-ala^2]$-leucine enkephalinamide (YAGFL), in the nasal, rectal and vaginal mucosal and serosal extracts of rabbits, effects of enzyme inhibitors such as amastatin (AM), puromycin (PM), thiorphan (TP), thimerosal (TM), EDTA, N-carboxymethyl-Phe-Leu (CPL), phenylethyl alcohol (PEA), phenylmercuric acetate (PMA), benzalkonium chloride (BC) and modified cyclodextrins, alone or in combination, were observed by assaying the pentapeptides staying intact during incubation. Mucosa extracts were prepared by exposing freshly-excised mucosal specimens mounted on Valia-Chien cells to isotonic phosphate buffer while stirring. The degradation of Leu-Enk and YAGFL followed the apparent first-order kinetics. The half-lives (mean) in the nasal, rectal and vaginal mucosal extracts were found to be 1.07, 0.33 and 1.14 hr for Leu-Enk, and 16.9, 6.2 and 6.8 hr for YAGFL, respectively. AM or PM, which is an aminopeptidase inhibitor, did not show a sufficient inhibition of Leu-Enk $(50\;{\mu}g/ml)$ degradation in all kinds of extracts. $Dimethyl-{\beta}-cyclodextrin\;(DM-{\beta}-CyD)$ decreased the degradation rate constants of Leu-Enk about 2 or 3 times, comparing with no additive. However, the use of mixed inhibitors of AM $(50\;{\mu}M)$/TM (0.25 mM)/EDTA (5 mM) resulted in a full stabilization of Leu-Enk by decreasing the degradation rate constants 67.3, 161.3 and 113.8 times far the nasal, rectal and vaginal mucosal extracts, respectively, comparing with no inhibitor. With mixed inhibitors, Leu-Enk remained intact more than 90% after 6 hr-incubation. In the stabilization of YAGFL, hM, TP or CPL alone showed little efffct, and some additives demonstrated a considerable inhibition of YAGFL degradation in the rank order of TM > BC > EDTA. However, the addition of mixed inhibitors such as TM (0.5 mM) and EDTA (5 mM) into the extracts protected YAGFL from the degradation by more than 85% even after 24 hr-incubation, suggesting almost complete inhibition of YAGFL degradation in the extract. On the other hand, $DM-{\beta}-CyD\;or\;hydroxypropyl-{\beta}-cyclodextrin$ (10%) were also found to retard enzymatic degradation rates of YAGFL markedly, and resulted in staying intact more than 80% of YAGFL in the nasal and vaginal mucosal extracts, and more than 60% in the rectal mucosal extract after 16 hr-incubation.

• KSBB Journal
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• v.8 no.4
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• pp.341-350
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• 1993

As an effort to develop an alternative transportation fuel, the production of methanol from methane gas was studied using the resting cells of an obligatory methanotroph, Methylosinus trichosporium OB3b. The reaction was carried out in high concentration phosphate buffer solutions with the flask-grown cells containing the exclusively cytoplasmic methane monooxygenase (sMMO) activity. The methanol accumulation rate was observed to be 79nmo1/mg·min during the initial 4.5hr. Phosphate-dependent inhibition was found for both sMMO and methanol dehydrogenase (MDH) activities, and the inhibition constants were 185mM and 42mM, respectively. The inhibition mode was noncompetitive. Methanol was found to be very inhibitory to the sMMO activity and the inhibition constant (noncompetitive) was 21mM when propylene was used as substrate. The sMO activity in the resting cells was declined very fast and the rate became very high during the methanol production. These results indicate that the use of M. trichosporium OB3b as a biocatalyst for the methanol production is heavily dependent on the stable maintenance of the whole-cell SMO activity as well as the effective alleviation of product inhibition.

• Biomedical Science Letters
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• v.12 no.1
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• pp.17-22
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• 2006

The baculovirus expression system is a powerful method for producing large amounts of the human erythrocyte-type glucose transport protein, heterologously. Characterization of the expressed protein is expected to show its ability to transport sugars directly. To achieve this, it is a prerequisite to know the properties of the endogenous sugar transport system in Spodoptera frugiperda Clone 21 (Sf21) cells, which are commonly employed as a host permissive cell line to support the baculovirus replication. The Sf21 cells can grow well on TC-100 medium that contains 0.1% D-glucose as the major carbon source, strongly suggesting the presence of endogenous glucose transport system. However, unlike the human glucose transport protein that has a broad substrate and inhibitor specificity, very little is known about the nature of the endogenous sugar transport system in Sf21 cells. In order to characterize further the inhibitor recognition properties of the Sf21 cell transporter, the ability of phloretin, cytochalasin B and D-fructose to inhibit 2-deoxy-D-glucose (2dGlc) transport was examined by measuring inhibition constants $(K_i)$. The $K_i's$ for reversible inhibitors were determined from plots of uptake versus inhibitor concentration. The 2dGlc transport in the Sf21 cells was very potently inhibited by phloretin, the aglucone of phlorizin with a $K_i$ similar to the value of about $2{\mu}M$ reported for inhibition of glucose transport in human erythrocytes. However, the Sf21 cell transport system was found to differ from the human transport protein in being much less sensitive to inhibition by cytochalasin B (apparent $K_i$ approximately $10\;{\mu}M$). In contrast, It is reported that the inhibitor binds the human erythrocyte counterpart with a $K_d$ of approximately $0.12\;{\mu}M$. Interestingly, the Sf21 glucose transport system also appeared to have high affinity for D-fructose with a $K_i$ of approximately 5mM, contrasting the reported $K_m$ of the human erythrocyte transport protein for the ketose of 1.5M.

• Microbiology and Biotechnology Letters
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• v.21 no.4
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• pp.342-347
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• 1993

It was proved that the cell growth followed a photo-inhibition model in light-limited turbidostat cultivation, having 1.06 (1/h) of maximum specific growth rate and 0.00094(kcal/$cm^2$/h) and 0.063 (kcal/$cm^2$/h) as half saturation and light inhibition constants, repectively. ${\beta}$-carotene production showed a growth related porcess. And the activation energy of Dunaliella salina was roughly estimated as 12.36 (kcal/mole) in employing Arrhenius relationship. It should also point out that relatively much porduction of ${\beta}$-carotene was observed at hight light intensity with yieding 1.04 (mg-carotene/g-dry cell/day) of specific product production rate while the cell growth was decreased. The optimal conditions of producing ${\beta}$-carotene in turbiodostat cultivation were as follows: $7.5{\times}10^{-3}$(kcal/$cm^2$/h)of light intensity, 2 (mM) and 50(mM) of nitrate and sodium bicarbonate concentrations and 100(ml/h) of $CO_2$ flow rate.

• Korean Journal of Microbiology
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• v.20 no.4
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• pp.189-194
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• 1982

Acid protease produced from Aspergillus tubingensis was pruified by ethanol fractionation, dialysis, and DEAE cellulose column chromatography. As a result of purification its specific activity increased to 5.4 times, and percent recovery was 39. The kinetic constants of the enzyme were studied. Km and Vmax was $1.5{\times}10^{-7}M\;and\;0.11{\Delta}O.D/min$ , respectively, when casein was used as substrate. The order of Km value of several proteins is : casein

• Journal of the Korean Chemical Society
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• v.34 no.3
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• pp.288-296
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• 1990

Antielastic fragment in GBⅠ-Ⅱ differ on $P_1$ site with that of antitryptic fragment in LBI. To obtain further understanding of the role of amino acid residue near the reactive site, specificity of $P_1$ site and loop size, Tyr substituted cyclic nonapeptide and cyclic pentapeptide were synthesized and the inhibition constants for some proteinases were calculated by Dixon method. Cyclic nonapeptide showed no inhibition for chymotrypsin but appeared low inhibitory activity for trypsin and elastase and that of cyclic pentapeptide possessed inhibitory activity for chymotrypsin.

• Korean journal of applied entomology
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• v.31 no.2
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• pp.122-132
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• 1992

Experiments were conducted to establish an in vitro AChE inhibition test system to evaluate the potency of AChE inhibition of new chemical compounds. For a fixed time inhibition test, optimal inhibition (incubation) time to evaluate their AChE inhibition potency was 10 min. for AChE inhibitors such as DFP, DDVP, and paraoxon. The concentration of new chemical compounds with an ester group for evaluation of their inhibition potency was 10 $\mu$M under 10 min. preincubation conditions. However, the stepwise inhibition test with higher concentrations seemed to be needed for other chemical compounds. For a progressive inhibition test to calculate inhibition constants such as $K_d$, $K_3$ and $K_i$, extremely low $K_d(1.3\times10-^85.6\times10^{-7})$ and $K_3$(0. 21-0.27 $min^{-1}$) were observed under lagged preincubation time (0.8-13.3 min) and low in¬hibitor concentrations $(1\times10-^92\times10-^6M)$. However, this method seemed to be useful for comparison of AChE inhibition potency among inhibitors. Differences in inhibition potency among DFP, paraoxon, and KH501 were due to the differences in $K_d$, in other words, differences in affinities between inhibitors and AChEs. Therefore, AntiChE screening should consist of two steps. The first step is to evaluate the potency of AChE inhibition based on $I_50$ valuse obtained from fixed time inhibition tests. The second step is to study inhibition patterns and characteristics of chemical compounds selected in the first step.